neckla_3.miz



    begin

    reserve A,B,a,b,c,d,e,f,g,h for set;

    theorem :: NECKLA_3:1

    

     Th1: (( id A) | B) = (( id A) /\ [:B, B:])

    proof

      thus (( id A) | B) c= (( id A) /\ [:B, B:])

      proof

        let a be object;

        assume

         A1: a in (( id A) | B);

        (( id A) | B) is Relation of B, A by RELSET_1: 18;

        then

        consider x,y be object such that

         A2: a = [x, y] and

         A3: x in B and y in A by A1, RELSET_1: 2;

        

         A4: [x, y] in ( id A) by A1, A2, RELAT_1:def 11;

        then x = y by RELAT_1:def 10;

        then [x, y] in [:B, B:] by A3, ZFMISC_1: 87;

        hence thesis by A2, A4, XBOOLE_0:def 4;

      end;

      let a be object;

      assume

       A5: a in (( id A) /\ [:B, B:]);

      then a in [:B, B:] by XBOOLE_0:def 4;

      then

       A6: ex x1,y1 be object st x1 in B & y1 in B & a = [x1, y1] by ZFMISC_1:def 2;

      a in ( id A) by A5, XBOOLE_0:def 4;

      hence thesis by A6, RELAT_1:def 11;

    end;

    theorem :: NECKLA_3:2

    ( id {a, b, c, d}) = { [a, a], [b, b], [c, c], [d, d]}

    proof

      set X = {a, b, c, d};

      thus ( id X) c= { [a, a], [b, b], [c, c], [d, d]}

      proof

        let x be object;

        assume

         A1: x in ( id X);

        then

        consider x1,y1 be object such that

         A2: x = [x1, y1] and

         A3: x1 in X and y1 in X by RELSET_1: 2;

        

         A4: x1 = y1 by A1, A2, RELAT_1:def 10;

        per cases by A3, ENUMSET1:def 2;

          suppose x1 = a;

          hence thesis by A2, A4, ENUMSET1:def 2;

        end;

          suppose x1 = b;

          hence thesis by A2, A4, ENUMSET1:def 2;

        end;

          suppose x1 = c;

          hence thesis by A2, A4, ENUMSET1:def 2;

        end;

          suppose x1 = d;

          hence thesis by A2, A4, ENUMSET1:def 2;

        end;

      end;

      let x be object;

      assume

       A5: x in { [a, a], [b, b], [c, c], [d, d]};

      per cases by A5, ENUMSET1:def 2;

        suppose

         A6: x = [a, a];

        a in X by ENUMSET1:def 2;

        hence thesis by A6, RELAT_1:def 10;

      end;

        suppose

         A7: x = [b, b];

        b in X by ENUMSET1:def 2;

        hence thesis by A7, RELAT_1:def 10;

      end;

        suppose

         A8: x = [c, c];

        c in X by ENUMSET1:def 2;

        hence thesis by A8, RELAT_1:def 10;

      end;

        suppose

         A9: x = [d, d];

        d in X by ENUMSET1:def 2;

        hence thesis by A9, RELAT_1:def 10;

      end;

    end;

    theorem :: NECKLA_3:3

    

     Th3: [: {a, b, c, d}, {e, f, g, h}:] = ( { [a, e], [a, f], [b, e], [b, f], [a, g], [a, h], [b, g], [b, h]} \/ { [c, e], [c, f], [d, e], [d, f], [c, g], [c, h], [d, g], [d, h]})

    proof

      set X1 = {a, b, c, d}, Y1 = {e, f, g, h}, X11 = {a, b}, X12 = {c, d}, Y11 = {e, f}, Y12 = {g, h};

      

       A1: [:X12, Y11:] = { [c, e], [c, f], [d, e], [d, f]} & [:X12, Y12:] = { [c, g], [c, h], [d, g], [d, h]} by MCART_1: 23;

      X1 = (X11 \/ X12) & Y1 = (Y11 \/ Y12) by ENUMSET1: 5;

      then

       A2: [:X1, Y1:] = ((( [:X11, Y11:] \/ [:X11, Y12:]) \/ [:X12, Y11:]) \/ [:X12, Y12:]) by ZFMISC_1: 98;

       [:X11, Y11:] = { [a, e], [a, f], [b, e], [b, f]} & [:X11, Y12:] = { [a, g], [a, h], [b, g], [b, h]} by MCART_1: 23;

      

      then [:X1, Y1:] = (( { [a, e], [a, f], [b, e], [b, f], [a, g], [a, h], [b, g], [b, h]} \/ { [c, e], [c, f], [d, e], [d, f]}) \/ { [c, g], [c, h], [d, g], [d, h]}) by A1, A2, ENUMSET1: 25

      .= ( { [a, e], [a, f], [b, e], [b, f], [a, g], [a, h], [b, g], [b, h]} \/ ( { [c, e], [c, f], [d, e], [d, f]} \/ { [c, g], [c, h], [d, g], [d, h]})) by XBOOLE_1: 4

      .= ( { [a, e], [a, f], [b, e], [b, f], [a, g], [a, h], [b, g], [b, h]} \/ { [c, e], [c, f], [d, e], [d, f], [c, g], [c, h], [d, g], [d, h]}) by ENUMSET1: 25;

      hence thesis;

    end;

    registration

      let X,Y be trivial set;

      cluster -> trivial for Relation of X, Y;

      correctness ;

    end

    theorem :: NECKLA_3:4

    

     Th4: for X be trivial set, R be Relation of X st R is non empty holds ex x be object st R = { [x, x]}

    proof

      let X be trivial set;

      let R be Relation of X;

      assume R is non empty;

      then

      consider x be object such that

       A1: x in R;

      consider y,z be object such that

       A2: x = [y, z] and

       A3: y in X and

       A4: z in X by A1, RELSET_1: 2;

      consider a be object such that

       A5: X = {a} by A3, ZFMISC_1: 131;

      

       A6: y = a & z = a by A3, A4, A5, TARSKI:def 1;

      R = { [a, a]}

      proof

        thus R c= { [a, a]}

        proof

          let r be object;

          assume r in R;

          then

          consider y,z be object such that

           A7: r = [y, z] and

           A8: y in X & z in X by RELSET_1: 2;

          y = a & z = a by A5, A8, TARSKI:def 1;

          hence thesis by A7, TARSKI:def 1;

        end;

        let z be object;

        assume z in { [a, a]};

        hence thesis by A1, A2, A6, TARSKI:def 1;

      end;

      hence thesis;

    end;

    registration

      let X be trivial set;

      cluster -> trivial reflexive symmetric transitive strongly_connected for Relation of X;

      correctness

      proof

        let R be Relation of X, X;

        

         A1: R is_reflexive_in ( field R)

        proof

          per cases ;

            suppose

             A2: R is empty;

            let x be object;

            assume x in ( field R);

            hence thesis by A2, RELAT_1: 40;

          end;

            suppose R is non empty;

            then

            consider z be object such that

             A3: R = { [z, z]} by Th4;

            let x be object;

            assume x in ( field R);

            then

             A4: x in (( dom R) \/ ( rng R)) by RELAT_1:def 6;

            ( dom R) = {z} & ( rng R) = {z} by A3, RELAT_1: 9;

            then x = z by A4, TARSKI:def 1;

            hence thesis by A3, TARSKI:def 1;

          end;

        end;

        

         A5: R is_transitive_in ( field R)

        proof

          per cases ;

            suppose

             A6: R is empty;

            let x,y,z be object;

            assume that x in ( field R) and y in ( field R) and z in ( field R) and

             A7: [x, y] in R and [y, z] in R;

            thus thesis by A6, A7;

          end;

            suppose

             A8: R is non empty;

            let x,y,z be object;

            assume that x in ( field R) and y in ( field R) and z in ( field R) and

             A9: [x, y] in R and

             A10: [y, z] in R;

            consider a be object such that

             A11: R = { [a, a]} by A8, Th4;

             [y, z] = [a, a] by A11, A10, TARSKI:def 1;

            then

             A12: z = a by XTUPLE_0: 1;

             [x, y] = [a, a] by A11, A9, TARSKI:def 1;

            then x = a by XTUPLE_0: 1;

            hence thesis by A11, A12, TARSKI:def 1;

          end;

        end;

        

         A13: R is_strongly_connected_in ( field R)

        proof

          per cases ;

            suppose

             A14: R is empty;

            let x,y be object;

            assume that

             A15: x in ( field R) and y in ( field R);

            thus thesis by A14, A15, RELAT_1: 40;

          end;

            suppose

             A16: R is non empty;

            let x,y be object;

            assume that

             A17: x in ( field R) and

             A18: y in ( field R);

            consider a be object such that

             A19: R = { [a, a]} by A16, Th4;

            

             A20: ( dom R) = {a} & ( rng R) = {a} by A19, RELAT_1: 9;

            y in (( dom R) \/ ( rng R)) by A18, RELAT_1:def 6;

            then

             A21: y = a by A20, TARSKI:def 1;

            x in (( dom R) \/ ( rng R)) by A17, RELAT_1:def 6;

            then x = a by A20, TARSKI:def 1;

            hence thesis by A19, A21, TARSKI:def 1;

          end;

        end;

        R is_symmetric_in ( field R)

        proof

          per cases ;

            suppose

             A22: R is empty;

            let x,y be object;

            assume that x in ( field R) and y in ( field R) and

             A23: [x, y] in R;

            thus thesis by A22, A23;

          end;

            suppose

             A24: R is non empty;

            let x,y be object;

            assume that x in ( field R) and y in ( field R) and

             A25: [x, y] in R;

            consider a be object such that

             A26: R = { [a, a]} by A24, Th4;

             [x, y] = [a, a] by A26, A25, TARSKI:def 1;

            then x = a & y = a by XTUPLE_0: 1;

            hence thesis by A26, TARSKI:def 1;

          end;

        end;

        hence thesis by A1, A5, A13;

      end;

    end

    theorem :: NECKLA_3:5

    

     Th5: for X be 1 -element set, R be Relation of X holds R is_symmetric_in X

    proof

      let X be 1 -element set;

      let R be Relation of X;

      consider x be object such that

       A1: X = {x} by ZFMISC_1: 131;

      let a,b be object;

      assume that

       A2: a in X and

       A3: b in X & [a, b] in R;

      a = x by A1, A2, TARSKI:def 1;

      hence thesis by A1, A3, TARSKI:def 1;

    end;

    registration

      cluster non empty strict finite irreflexive symmetric for RelStr;

      correctness

      proof

        set X = { 0 , 1}, r = { [ 0 , 1], [1, 0 ]};

         0 in X & 1 in X by TARSKI:def 2;

        then

         A1: [ 0 , 1] in [:X, X:] & [1, 0 ] in [:X, X:] by ZFMISC_1:def 2;

        r c= [:X, X:] by A1, TARSKI:def 2;

        then

        reconsider r as Relation of X, X;

        take R = RelStr (# X, r #);

        

         A2: for x be set st x in the carrier of R holds not [x, x] in the InternalRel of R

        proof

          let x be set;

          

           A3: not [ 0 , 0 ] in r

          proof

            assume [ 0 , 0 ] in r;

            then [ 0 , 0 ] = [ 0 , 1] or [ 0 , 0 ] = [1, 0 ] by TARSKI:def 2;

            hence contradiction by XTUPLE_0: 1;

          end;

          

           A4: not [1, 1] in r

          proof

            assume [1, 1] in r;

            then [1, 1] = [ 0 , 1] or [1, 1] = [1, 0 ] by TARSKI:def 2;

            hence contradiction by XTUPLE_0: 1;

          end;

          assume x in the carrier of R;

          then x = 0 or x = 1 by TARSKI:def 2;

          hence thesis by A3, A4;

        end;

        for x,y be object st x in X & y in X & [x, y] in r holds [y, x] in r

        proof

          let x,y be object;

          assume that x in X and y in X and

           A5: [x, y] in r;

          per cases by A5, TARSKI:def 2;

            suppose [x, y] = [ 0 , 1];

            then x = 0 & y = 1 by XTUPLE_0: 1;

            hence thesis by TARSKI:def 2;

          end;

            suppose [x, y] = [1, 0 ];

            then x = 1 & y = 0 by XTUPLE_0: 1;

            hence thesis by TARSKI:def 2;

          end;

        end;

        then r is_symmetric_in X;

        hence thesis by A2;

      end;

    end

    registration

      let L be irreflexive RelStr;

      cluster -> irreflexive for full SubRelStr of L;

      correctness

      proof

        let S be full SubRelStr of L;

        let x be set;

        assume

         A1: x in the carrier of S;

        the carrier of S c= the carrier of L by YELLOW_0:def 13;

        then the InternalRel of S = (the InternalRel of L |_2 the carrier of S) & not [x, x] in the InternalRel of L by A1, NECKLACE:def 5, YELLOW_0:def 14;

        hence thesis by XBOOLE_0:def 4;

      end;

    end

    registration

      let L be symmetric RelStr;

      cluster -> symmetric for full SubRelStr of L;

      correctness

      proof

        let S be full SubRelStr of L;

        let x,y be object;

        assume that

         A1: x in the carrier of S & y in the carrier of S and

         A2: [x, y] in the InternalRel of S;

        

         A3: [y, x] in [:the carrier of S, the carrier of S:] by A1, ZFMISC_1: 87;

        

         A4: the carrier of S c= the carrier of L & the InternalRel of L is_symmetric_in the carrier of L by NECKLACE:def 3, YELLOW_0:def 13;

        

         A5: the InternalRel of S = (the InternalRel of L |_2 the carrier of S) by YELLOW_0:def 14;

        then [x, y] in the InternalRel of L by A2, XBOOLE_0:def 4;

        then [y, x] in the InternalRel of L by A1, A4;

        hence thesis by A5, A3, XBOOLE_0:def 4;

      end;

    end

    theorem :: NECKLA_3:6

    

     Th6: for R be irreflexive symmetric RelStr st ( card the carrier of R) = 2 holds ex a,b be object st the carrier of R = {a, b} & (the InternalRel of R = { [a, b], [b, a]} or the InternalRel of R = {} )

    proof

      let R be irreflexive symmetric RelStr;

      set Q = the InternalRel of R;

      assume

       A1: ( card the carrier of R) = 2;

      then

      reconsider X = the carrier of R as finite set;

      consider a,b be object such that

       A2: a <> b and

       A3: X = {a, b} by A1, CARD_2: 60;

      

       A4: the InternalRel of R c= { [a, b], [b, a]}

      proof

        let x be object;

        assume

         A5: x in the InternalRel of R;

        then

        consider x1,x2 be object such that

         A6: x = [x1, x2] and

         A7: x1 in X and

         A8: x2 in X by RELSET_1: 2;

        

         A9: x1 = a or x1 = b by A3, A7, TARSKI:def 2;

        per cases by A3, A6, A8, A9, TARSKI:def 2;

          suppose

           A10: x = [a, a];

          a in the carrier of R by A3, TARSKI:def 2;

          hence thesis by A5, A10, NECKLACE:def 5;

        end;

          suppose x = [a, b];

          hence thesis by TARSKI:def 2;

        end;

          suppose x = [b, a];

          hence thesis by TARSKI:def 2;

        end;

          suppose

           A11: x = [b, b];

          b in the carrier of R by A3, TARSKI:def 2;

          hence thesis by A5, A11, NECKLACE:def 5;

        end;

      end;

      per cases by A4, ZFMISC_1: 36;

        suppose Q = {} ;

        hence thesis by A3;

      end;

        suppose

         A12: Q = { [a, b]};

        

         A13: a in X & b in X by A3, TARSKI:def 2;

        

         A14: Q is_symmetric_in X by NECKLACE:def 3;

         [a, b] in Q by A12, TARSKI:def 1;

        then [b, a] in Q by A13, A14;

        then [b, a] = [a, b] by A12, TARSKI:def 1;

        hence thesis by A2, XTUPLE_0: 1;

      end;

        suppose

         A15: Q = { [b, a]};

        

         A16: a in X & b in X by A3, TARSKI:def 2;

        

         A17: Q is_symmetric_in X by NECKLACE:def 3;

         [b, a] in Q by A15, TARSKI:def 1;

        then [a, b] in Q by A16, A17;

        then [b, a] = [a, b] by A15, TARSKI:def 1;

        hence thesis by A2, XTUPLE_0: 1;

      end;

        suppose Q = { [a, b], [b, a]};

        hence thesis by A3;

      end;

    end;

    begin

    registration

      let R be non empty RelStr, S be RelStr;

      cluster ( union_of (R,S)) -> non empty;

      correctness

      proof

        (the carrier of R \/ the carrier of S) is non empty;

        hence thesis by NECKLA_2:def 2;

      end;

      cluster ( sum_of (R,S)) -> non empty;

      correctness

      proof

        (the carrier of R \/ the carrier of S) is non empty;

        hence thesis by NECKLA_2:def 3;

      end;

    end

    registration

      let R be RelStr, S be non empty RelStr;

      cluster ( union_of (R,S)) -> non empty;

      correctness

      proof

        (the carrier of R \/ the carrier of S) is non empty;

        hence thesis by NECKLA_2:def 2;

      end;

      cluster ( sum_of (R,S)) -> non empty;

      correctness

      proof

        (the carrier of R \/ the carrier of S) is non empty;

        hence thesis by NECKLA_2:def 3;

      end;

    end

    registration

      let R,S be finite RelStr;

      cluster ( union_of (R,S)) -> finite;

      correctness

      proof

        (the carrier of R \/ the carrier of S) is finite;

        hence thesis by NECKLA_2:def 2;

      end;

      cluster ( sum_of (R,S)) -> finite;

      correctness

      proof

        (the carrier of R \/ the carrier of S) is finite;

        hence thesis by NECKLA_2:def 3;

      end;

    end

    registration

      let R,S be symmetric RelStr;

      cluster ( union_of (R,S)) -> symmetric;

      correctness

      proof

        let x,y be object;

        set U = ( union_of (R,S)), cU = the carrier of U, IU = the InternalRel of U, cR = the carrier of R, cS = the carrier of S;

        assume that x in cU and y in cU and

         A1: [x, y] in IU;

        

         A2: [x, y] in (the InternalRel of R \/ the InternalRel of S) by A1, NECKLA_2:def 2;

        per cases by A2, XBOOLE_0:def 3;

          suppose

           A3: [x, y] in the InternalRel of R;

          

           A4: the InternalRel of R is_symmetric_in cR by NECKLACE:def 3;

          x in cR & y in cR by A3, ZFMISC_1: 87;

          then [y, x] in the InternalRel of R by A3, A4;

          then [y, x] in (the InternalRel of R \/ the InternalRel of S) by XBOOLE_0:def 3;

          hence thesis by NECKLA_2:def 2;

        end;

          suppose

           A5: [x, y] in the InternalRel of S;

          

           A6: the InternalRel of S is_symmetric_in cS by NECKLACE:def 3;

          x in cS & y in cS by A5, ZFMISC_1: 87;

          then [y, x] in the InternalRel of S by A5, A6;

          then [y, x] in (the InternalRel of R \/ the InternalRel of S) by XBOOLE_0:def 3;

          hence thesis by NECKLA_2:def 2;

        end;

      end;

      cluster ( sum_of (R,S)) -> symmetric;

      correctness

      proof

        set SU = ( sum_of (R,S)), cSU = the carrier of ( sum_of (R,S)), ISU = the InternalRel of SU, cR = the carrier of R, IR = the InternalRel of R, cS = the carrier of S, IS = the InternalRel of S;

        

         A7: IS is_symmetric_in cS by NECKLACE:def 3;

        

         A8: IR is_symmetric_in cR by NECKLACE:def 3;

        the InternalRel of ( sum_of (R,S)) is_symmetric_in cSU

        proof

          let x,y be object;

          assume that x in cSU and y in cSU and

           A9: [x, y] in ISU;

           [x, y] in (((IR \/ IS) \/ [:cR, cS:]) \/ [:cS, cR:]) by A9, NECKLA_2:def 3;

          then [x, y] in ((IR \/ IS) \/ [:cR, cS:]) or [x, y] in [:cS, cR:] by XBOOLE_0:def 3;

          then

           A10: [x, y] in (IR \/ IS) or [x, y] in [:cR, cS:] or [x, y] in [:cS, cR:] by XBOOLE_0:def 3;

          per cases by A10, XBOOLE_0:def 3;

            suppose

             A11: [x, y] in IR;

            then x in cR & y in cR by ZFMISC_1: 87;

            then [y, x] in IR by A8, A11;

            then [y, x] in (IR \/ IS) by XBOOLE_0:def 3;

            then [y, x] in ((IR \/ IS) \/ [:cR, cS:]) by XBOOLE_0:def 3;

            then [y, x] in (((IR \/ IS) \/ [:cR, cS:]) \/ [:cS, cR:]) by XBOOLE_0:def 3;

            hence thesis by NECKLA_2:def 3;

          end;

            suppose

             A12: [x, y] in IS;

            then x in cS & y in cS by ZFMISC_1: 87;

            then [y, x] in IS by A7, A12;

            then [y, x] in (IR \/ IS) by XBOOLE_0:def 3;

            then [y, x] in ((IR \/ IS) \/ [:cR, cS:]) by XBOOLE_0:def 3;

            then [y, x] in (((IR \/ IS) \/ [:cR, cS:]) \/ [:cS, cR:]) by XBOOLE_0:def 3;

            hence thesis by NECKLA_2:def 3;

          end;

            suppose [x, y] in [:cR, cS:];

            then x in cR & y in cS by ZFMISC_1: 87;

            then [y, x] in [:cS, cR:] by ZFMISC_1: 87;

            then [y, x] in ( [:cR, cS:] \/ [:cS, cR:]) by XBOOLE_0:def 3;

            then [y, x] in (IS \/ ( [:cR, cS:] \/ [:cS, cR:])) by XBOOLE_0:def 3;

            then [y, x] in ((IS \/ [:cR, cS:]) \/ [:cS, cR:]) by XBOOLE_1: 4;

            then [y, x] in (IR \/ ((IS \/ [:cR, cS:]) \/ [:cS, cR:])) by XBOOLE_0:def 3;

            then [y, x] in (IR \/ (IS \/ ( [:cR, cS:] \/ [:cS, cR:]))) by XBOOLE_1: 4;

            then [y, x] in ((IR \/ IS) \/ ( [:cR, cS:] \/ [:cS, cR:])) by XBOOLE_1: 4;

            then [y, x] in (((IR \/ IS) \/ [:cR, cS:]) \/ [:cS, cR:]) by XBOOLE_1: 4;

            hence thesis by NECKLA_2:def 3;

          end;

            suppose [x, y] in [:cS, cR:];

            then x in cS & y in cR by ZFMISC_1: 87;

            then [y, x] in [:cR, cS:] by ZFMISC_1: 87;

            then [y, x] in ( [:cR, cS:] \/ [:cS, cR:]) by XBOOLE_0:def 3;

            then [y, x] in (IS \/ ( [:cR, cS:] \/ [:cS, cR:])) by XBOOLE_0:def 3;

            then [y, x] in ((IS \/ [:cR, cS:]) \/ [:cS, cR:]) by XBOOLE_1: 4;

            then [y, x] in (IR \/ ((IS \/ [:cR, cS:]) \/ [:cS, cR:])) by XBOOLE_0:def 3;

            then [y, x] in (IR \/ (IS \/ ( [:cR, cS:] \/ [:cS, cR:]))) by XBOOLE_1: 4;

            then [y, x] in ((IR \/ IS) \/ ( [:cR, cS:] \/ [:cS, cR:])) by XBOOLE_1: 4;

            then [y, x] in (((IR \/ IS) \/ [:cR, cS:]) \/ [:cS, cR:]) by XBOOLE_1: 4;

            hence thesis by NECKLA_2:def 3;

          end;

        end;

        hence thesis;

      end;

    end

    registration

      let R,S be irreflexive RelStr;

      cluster ( union_of (R,S)) -> irreflexive;

      correctness

      proof

        set U = ( union_of (R,S)), cU = the carrier of U, IU = the InternalRel of U, cR = the carrier of R, cS = the carrier of S;

        for x be set st x in cU holds not [x, x] in IU

        proof

          let x be set such that x in cU;

          assume not thesis;

          then

           A1: [x, x] in (the InternalRel of R \/ the InternalRel of S) by NECKLA_2:def 2;

          per cases by A1, XBOOLE_0:def 3;

            suppose

             A2: [x, x] in the InternalRel of R;

            then x in cR by ZFMISC_1: 87;

            hence thesis by A2, NECKLACE:def 5;

          end;

            suppose

             A3: [x, x] in the InternalRel of S;

            then x in cS by ZFMISC_1: 87;

            hence thesis by A3, NECKLACE:def 5;

          end;

        end;

        hence thesis;

      end;

    end

    theorem :: NECKLA_3:7

    for R,S be irreflexive RelStr st the carrier of R misses the carrier of S holds ( sum_of (R,S)) is irreflexive

    proof

      let R,S be irreflexive RelStr such that

       A1: the carrier of R misses the carrier of S;

      for x be set st x in the carrier of ( sum_of (R,S)) holds not [x, x] in the InternalRel of ( sum_of (R,S))

      proof

        set IR = the InternalRel of R, IS = the InternalRel of S, RS = [:the carrier of R, the carrier of S:], SR = [:the carrier of S, the carrier of R:];

        let x be set;

        assume x in the carrier of ( sum_of (R,S));

        assume not thesis;

        then [x, x] in (((IR \/ IS) \/ RS) \/ SR) by NECKLA_2:def 3;

        then [x, x] in ((IR \/ IS) \/ RS) or [x, x] in SR by XBOOLE_0:def 3;

        then

         A2: [x, x] in (IR \/ IS) or [x, x] in RS or [x, x] in SR by XBOOLE_0:def 3;

        per cases by A2, XBOOLE_0:def 3;

          suppose

           A3: [x, x] in IR;

          then x in the carrier of R by ZFMISC_1: 87;

          hence thesis by A3, NECKLACE:def 5;

        end;

          suppose

           A4: [x, x] in IS;

          then x in the carrier of S by ZFMISC_1: 87;

          hence thesis by A4, NECKLACE:def 5;

        end;

          suppose [x, x] in RS;

          then x in the carrier of R & x in the carrier of S by ZFMISC_1: 87;

          hence thesis by A1, XBOOLE_0: 3;

        end;

          suppose [x, x] in SR;

          then x in the carrier of S & x in the carrier of R by ZFMISC_1: 87;

          hence thesis by A1, XBOOLE_0: 3;

        end;

      end;

      hence thesis;

    end;

    theorem :: NECKLA_3:8

    

     Th8: for R1,R2 be RelStr holds ( union_of (R1,R2)) = ( union_of (R2,R1)) & ( sum_of (R1,R2)) = ( sum_of (R2,R1))

    proof

      let R1,R2 be RelStr;

      set U1 = ( union_of (R1,R2)), S1 = ( sum_of (R1,R2));

      

       A1: the carrier of S1 = (the carrier of R2 \/ the carrier of R1) by NECKLA_2:def 3;

      

       A2: the InternalRel of S1 = (((the InternalRel of R1 \/ the InternalRel of R2) \/ [:the carrier of R1, the carrier of R2:]) \/ [:the carrier of R2, the carrier of R1:]) by NECKLA_2:def 3

      .= (((the InternalRel of R2 \/ the InternalRel of R1) \/ [:the carrier of R2, the carrier of R1:]) \/ [:the carrier of R1, the carrier of R2:]) by XBOOLE_1: 4;

      the carrier of U1 = (the carrier of R2 \/ the carrier of R1) & the InternalRel of U1 = (the InternalRel of R2 \/ the InternalRel of R1) by NECKLA_2:def 2;

      hence thesis by A1, A2, NECKLA_2:def 2, NECKLA_2:def 3;

    end;

    theorem :: NECKLA_3:9

    

     Th9: for G be irreflexive RelStr, G1,G2 be RelStr st (G = ( union_of (G1,G2)) or G = ( sum_of (G1,G2))) holds G1 is irreflexive & G2 is irreflexive

    proof

      let G be irreflexive RelStr, G1,G2 be RelStr;

      assume

       A1: G = ( union_of (G1,G2)) or G = ( sum_of (G1,G2));

      per cases by A1;

        suppose

         A2: G = ( union_of (G1,G2));

        assume

         A3: not thesis;

        thus thesis

        proof

          per cases by A3;

            suppose not G1 is irreflexive;

            then

            consider x be set such that

             A4: x in the carrier of G1 and

             A5: [x, x] in the InternalRel of G1;

             [x, x] in (the InternalRel of G1 \/ the InternalRel of G2) by A5, XBOOLE_0:def 3;

            then

             A6: [x, x] in the InternalRel of G by A2, NECKLA_2:def 2;

            x in (the carrier of G1 \/ the carrier of G2) by A4, XBOOLE_0:def 3;

            then x in the carrier of G by A2, NECKLA_2:def 2;

            hence thesis by A6, NECKLACE:def 5;

          end;

            suppose not G2 is irreflexive;

            then

            consider x be set such that

             A7: x in the carrier of G2 and

             A8: [x, x] in the InternalRel of G2;

             [x, x] in (the InternalRel of G1 \/ the InternalRel of G2) by A8, XBOOLE_0:def 3;

            then

             A9: [x, x] in the InternalRel of G by A2, NECKLA_2:def 2;

            x in (the carrier of G1 \/ the carrier of G2) by A7, XBOOLE_0:def 3;

            then x in the carrier of G by A2, NECKLA_2:def 2;

            hence thesis by A9, NECKLACE:def 5;

          end;

        end;

      end;

        suppose

         A10: G = ( sum_of (G1,G2));

        assume

         A11: not thesis;

        thus thesis

        proof

          per cases by A11;

            suppose not G1 is irreflexive;

            then

            consider x be set such that

             A12: x in the carrier of G1 and

             A13: [x, x] in the InternalRel of G1;

             [x, x] in (the InternalRel of G1 \/ the InternalRel of G2) by A13, XBOOLE_0:def 3;

            then [x, x] in ((the InternalRel of G1 \/ the InternalRel of G2) \/ [:the carrier of G1, the carrier of G2:]) by XBOOLE_0:def 3;

            then [x, x] in (((the InternalRel of G1 \/ the InternalRel of G2) \/ [:the carrier of G1, the carrier of G2:]) \/ [:the carrier of G2, the carrier of G1:]) by XBOOLE_0:def 3;

            then

             A14: [x, x] in the InternalRel of G by A10, NECKLA_2:def 3;

            x in (the carrier of G1 \/ the carrier of G2) by A12, XBOOLE_0:def 3;

            then x in the carrier of G by A10, NECKLA_2:def 3;

            hence thesis by A14, NECKLACE:def 5;

          end;

            suppose not G2 is irreflexive;

            then

            consider x be set such that

             A15: x in the carrier of G2 and

             A16: [x, x] in the InternalRel of G2;

             [x, x] in (the InternalRel of G1 \/ the InternalRel of G2) by A16, XBOOLE_0:def 3;

            then [x, x] in ((the InternalRel of G1 \/ the InternalRel of G2) \/ [:the carrier of G1, the carrier of G2:]) by XBOOLE_0:def 3;

            then [x, x] in (((the InternalRel of G1 \/ the InternalRel of G2) \/ [:the carrier of G1, the carrier of G2:]) \/ [:the carrier of G2, the carrier of G1:]) by XBOOLE_0:def 3;

            then

             A17: [x, x] in the InternalRel of G by A10, NECKLA_2:def 3;

            x in (the carrier of G1 \/ the carrier of G2) by A15, XBOOLE_0:def 3;

            then x in the carrier of G by A10, NECKLA_2:def 3;

            hence thesis by A17, NECKLACE:def 5;

          end;

        end;

      end;

    end;

    theorem :: NECKLA_3:10

    

     Th10: for G be non empty RelStr, H1,H2 be RelStr st the carrier of H1 misses the carrier of H2 & ( the RelStr of G = ( union_of (H1,H2)) or the RelStr of G = ( sum_of (H1,H2))) holds H1 is full SubRelStr of G & H2 is full SubRelStr of G

    proof

      let G be non empty RelStr;

      let H1,H2 be RelStr;

      assume that

       A1: the carrier of H1 misses the carrier of H2 and

       A2: the RelStr of G = ( union_of (H1,H2)) or the RelStr of G = ( sum_of (H1,H2));

      set cH1 = the carrier of H1, cH2 = the carrier of H2, IH1 = the InternalRel of H1, IH2 = the InternalRel of H2, H1H2 = [:cH1, cH2:], H2H1 = [:cH2, cH1:];

      per cases by A2;

        suppose

         A3: the RelStr of G = ( union_of (H1,H2));

        

         A4: IH2 = (the InternalRel of G |_2 cH2)

        proof

          thus IH2 c= (the InternalRel of G |_2 cH2)

          proof

            let a be object;

            the InternalRel of G = (IH1 \/ IH2) by A3, NECKLA_2:def 2;

            then

             A5: IH2 c= the InternalRel of G by XBOOLE_1: 7;

            assume a in IH2;

            hence thesis by A5, XBOOLE_0:def 4;

          end;

          let a be object;

          assume

           A6: a in (the InternalRel of G |_2 cH2);

          then

           A7: a in [:cH2, cH2:] by XBOOLE_0:def 4;

          a in the InternalRel of G by A6, XBOOLE_0:def 4;

          then

           A8: a in (IH1 \/ IH2) by A3, NECKLA_2:def 2;

          per cases by A8, XBOOLE_0:def 3;

            suppose a in IH1;

            then

            consider x,y be object such that

             A9: a = [x, y] and

             A10: x in cH1 and y in cH1 by RELSET_1: 2;

            consider x1,y1 be object such that

             A11: x1 in cH2 and y1 in cH2 and

             A12: a = [x1, y1] by A7, ZFMISC_1:def 2;

            x = x1 by A9, A12, XTUPLE_0: 1;

            then (cH1 /\ cH2) <> {} by A10, A11, XBOOLE_0:def 4;

            hence thesis by A1;

          end;

            suppose a in IH2;

            hence thesis;

          end;

        end;

        

         A13: IH1 = (the InternalRel of G |_2 cH1)

        proof

          thus IH1 c= (the InternalRel of G |_2 cH1)

          proof

            let a be object;

            the InternalRel of G = (IH1 \/ IH2) by A3, NECKLA_2:def 2;

            then

             A14: IH1 c= the InternalRel of G by XBOOLE_1: 7;

            assume a in IH1;

            hence thesis by A14, XBOOLE_0:def 4;

          end;

          let a be object;

          assume

           A15: a in (the InternalRel of G |_2 cH1);

          then

           A16: a in [:cH1, cH1:] by XBOOLE_0:def 4;

          a in the InternalRel of G by A15, XBOOLE_0:def 4;

          then

           A17: a in (IH1 \/ IH2) by A3, NECKLA_2:def 2;

          per cases by A17, XBOOLE_0:def 3;

            suppose a in IH1;

            hence thesis;

          end;

            suppose a in IH2;

            then

            consider x,y be object such that

             A18: a = [x, y] and

             A19: x in cH2 and y in cH2 by RELSET_1: 2;

            ex x1,y1 be object st x1 in cH1 & y1 in cH1 & a = [x1, y1] by A16, ZFMISC_1:def 2;

            then x in cH1 by A18, XTUPLE_0: 1;

            hence thesis by A1, A19, XBOOLE_0: 3;

          end;

        end;

        the carrier of G = (the carrier of H1 \/ the carrier of H2) by A3, NECKLA_2:def 2;

        then

         A20: the carrier of H1 c= the carrier of G & the carrier of H2 c= the carrier of G by XBOOLE_1: 7;

        the InternalRel of G = (IH1 \/ IH2) by A3, NECKLA_2:def 2;

        then IH1 c= the InternalRel of G & the InternalRel of H2 c= the InternalRel of G by XBOOLE_1: 7;

        hence thesis by A20, A13, A4, YELLOW_0:def 13, YELLOW_0:def 14;

      end;

        suppose

         A21: the RelStr of G = ( sum_of (H1,H2));

        

         A22: IH2 = (the InternalRel of G |_2 cH2)

        proof

          thus IH2 c= (the InternalRel of G |_2 cH2)

          proof

            let a be object;

            the InternalRel of G = (((IH1 \/ IH2) \/ H1H2) \/ H2H1) by A21, NECKLA_2:def 3;

            then the InternalRel of G = (IH2 \/ ((IH1 \/ H1H2) \/ H2H1)) by XBOOLE_1: 113;

            then

             A23: IH2 c= the InternalRel of G by XBOOLE_1: 7;

            assume a in IH2;

            hence thesis by A23, XBOOLE_0:def 4;

          end;

          let a be object;

          assume

           A24: a in (the InternalRel of G |_2 cH2);

          then

           A25: a in [:cH2, cH2:] by XBOOLE_0:def 4;

          a in the InternalRel of G by A24, XBOOLE_0:def 4;

          then a in (((IH1 \/ IH2) \/ H1H2) \/ H2H1) by A21, NECKLA_2:def 3;

          then a in (IH1 \/ ((IH2 \/ H1H2) \/ H2H1)) by XBOOLE_1: 113;

          then a in IH1 or a in ((IH2 \/ H1H2) \/ H2H1) by XBOOLE_0:def 3;

          then a in IH1 or a in (IH2 \/ (H1H2 \/ H2H1)) by XBOOLE_1: 4;

          then

           A26: a in IH1 or a in IH2 or a in (H1H2 \/ H2H1) by XBOOLE_0:def 3;

          per cases by A26, XBOOLE_0:def 3;

            suppose a in IH1;

            then

            consider x,y be object such that

             A27: a = [x, y] and

             A28: x in cH1 and y in cH1 by RELSET_1: 2;

            consider x1,y1 be object such that

             A29: x1 in cH2 and y1 in cH2 and

             A30: a = [x1, y1] by A25, ZFMISC_1:def 2;

            x = x1 by A27, A30, XTUPLE_0: 1;

            then (cH1 /\ cH2) <> {} by A28, A29, XBOOLE_0:def 4;

            hence thesis by A1;

          end;

            suppose a in IH2;

            hence thesis;

          end;

            suppose a in H1H2;

            then

            consider x,y be object such that

             A31: x in cH1 and y in cH2 and

             A32: a = [x, y] by ZFMISC_1:def 2;

            consider x1,y1 be object such that

             A33: x1 in cH2 and y1 in cH2 and

             A34: a = [x1, y1] by A25, ZFMISC_1:def 2;

            x = x1 by A32, A34, XTUPLE_0: 1;

            then (cH1 /\ cH2) <> {} by A31, A33, XBOOLE_0:def 4;

            hence thesis by A1;

          end;

            suppose a in H2H1;

            then

            consider x,y be object such that x in cH2 and

             A35: y in cH1 and

             A36: a = [x, y] by ZFMISC_1:def 2;

            consider x1,y1 be object such that x1 in cH2 and

             A37: y1 in cH2 and

             A38: a = [x1, y1] by A25, ZFMISC_1:def 2;

            y = y1 by A36, A38, XTUPLE_0: 1;

            then (cH1 /\ cH2) <> {} by A35, A37, XBOOLE_0:def 4;

            hence thesis by A1;

          end;

        end;

        IH2 c= ((IH1 \/ IH2) \/ [:cH1, cH2:]) by XBOOLE_1: 7, XBOOLE_1: 10;

        then

         A39: IH2 c= (((IH1 \/ IH2) \/ [:cH1, cH2:]) \/ [:cH2, cH1:]) by XBOOLE_1: 10;

        

         A40: IH1 = (the InternalRel of G |_2 cH1)

        proof

          thus IH1 c= (the InternalRel of G |_2 cH1)

          proof

            let a be object;

            the InternalRel of G = (((IH1 \/ IH2) \/ H1H2) \/ H2H1) by A21, NECKLA_2:def 3

            .= (IH1 \/ ((IH2 \/ H1H2) \/ H2H1)) by XBOOLE_1: 113;

            then

             A41: IH1 c= the InternalRel of G by XBOOLE_1: 7;

            assume a in IH1;

            hence thesis by A41, XBOOLE_0:def 4;

          end;

          let a be object;

          assume

           A42: a in (the InternalRel of G |_2 cH1);

          then

           A43: a in [:cH1, cH1:] by XBOOLE_0:def 4;

          a in the InternalRel of G by A42, XBOOLE_0:def 4;

          then a in (((IH1 \/ IH2) \/ H1H2) \/ H2H1) by A21, NECKLA_2:def 3;

          then a in (IH1 \/ ((IH2 \/ H1H2) \/ H2H1)) by XBOOLE_1: 113;

          then a in IH1 or a in ((IH2 \/ H1H2) \/ H2H1) by XBOOLE_0:def 3;

          then a in IH1 or a in (IH2 \/ (H1H2 \/ H2H1)) by XBOOLE_1: 4;

          then

           A44: a in IH1 or a in IH2 or a in (H1H2 \/ H2H1) by XBOOLE_0:def 3;

          per cases by A44, XBOOLE_0:def 3;

            suppose a in IH1;

            hence thesis;

          end;

            suppose a in IH2;

            then

            consider x,y be object such that

             A45: a = [x, y] and

             A46: x in cH2 and y in cH2 by RELSET_1: 2;

            consider x1,y1 be object such that

             A47: x1 in cH1 and y1 in cH1 and

             A48: a = [x1, y1] by A43, ZFMISC_1:def 2;

            x = x1 by A45, A48, XTUPLE_0: 1;

            then (cH1 /\ cH2) <> {} by A46, A47, XBOOLE_0:def 4;

            hence thesis by A1;

          end;

            suppose a in H1H2;

            then

            consider x,y be object such that x in cH1 and

             A49: y in cH2 and

             A50: a = [x, y] by ZFMISC_1:def 2;

            consider x1,y1 be object such that x1 in cH1 and

             A51: y1 in cH1 and

             A52: a = [x1, y1] by A43, ZFMISC_1:def 2;

            y = y1 by A50, A52, XTUPLE_0: 1;

            then (cH1 /\ cH2) <> {} by A49, A51, XBOOLE_0:def 4;

            hence thesis by A1;

          end;

            suppose a in H2H1;

            then

            consider x,y be object such that

             A53: x in cH2 and y in cH1 and

             A54: a = [x, y] by ZFMISC_1:def 2;

            consider x1,y1 be object such that

             A55: x1 in cH1 and y1 in cH1 and

             A56: a = [x1, y1] by A43, ZFMISC_1:def 2;

            x = x1 by A54, A56, XTUPLE_0: 1;

            then (cH1 /\ cH2) <> {} by A53, A55, XBOOLE_0:def 4;

            hence thesis by A1;

          end;

        end;

        IH1 c= (IH1 \/ (IH2 \/ [:cH1, cH2:])) by XBOOLE_1: 7;

        then

         A57: IH1 c= ((IH1 \/ IH2) \/ [:cH1, cH2:]) by XBOOLE_1: 4;

        the carrier of G = (the carrier of H1 \/ the carrier of H2) by A21, NECKLA_2:def 3;

        then

         A58: the carrier of H1 c= the carrier of G & the carrier of H2 c= the carrier of G by XBOOLE_1: 7;

        

         A59: the InternalRel of G = (((IH1 \/ IH2) \/ [:cH1, cH2:]) \/ [:cH2, cH1:]) by A21, NECKLA_2:def 3;

        then ((IH1 \/ IH2) \/ [:cH1, cH2:]) c= the InternalRel of G by XBOOLE_1: 7;

        then IH1 c= the InternalRel of G by A57;

        hence thesis by A59, A58, A39, A40, A22, YELLOW_0:def 13, YELLOW_0:def 14;

      end;

    end;

    begin

    theorem :: NECKLA_3:11

    

     Th11: the InternalRel of ( ComplRelStr ( Necklace 4)) = { [ 0 , 2], [2, 0 ], [ 0 , 3], [3, 0 ], [1, 3], [3, 1]}

    proof

      set N4 = ( Necklace 4), cN4 = the carrier of N4, CmpN4 = ( ComplRelStr N4);

      

       A1: the carrier of ( Necklace 4) = { 0 , 1, 2, 3} by NECKLACE: 1, NECKLACE: 20;

      thus the InternalRel of CmpN4 c= { [ 0 , 2], [2, 0 ], [ 0 , 3], [3, 0 ], [1, 3], [3, 1]}

      proof

        let x be object;

        assume x in the InternalRel of CmpN4;

        then

         A2: x in ((the InternalRel of N4 ` ) \ ( id cN4)) by NECKLACE:def 8;

        then

         A3: not x in ( id cN4) by XBOOLE_0:def 5;

        x in (the InternalRel of N4 ` ) by A2, XBOOLE_0:def 5;

        then

         A4: x in ( [:cN4, cN4:] \ the InternalRel of N4) by SUBSET_1:def 4;

        consider a1,b1 be object such that

         A5: a1 in cN4 and

         A6: b1 in cN4 and

         A7: x = [a1, b1] by A2, ZFMISC_1:def 2;

        per cases by A1, A5, A6, ENUMSET1:def 2;

          suppose a1 = 0 & b1 = 0 ;

          hence thesis by A3, A5, A7, RELAT_1:def 10;

        end;

          suppose a1 = 0 & b1 = 1;

          then x in the InternalRel of N4 by A7, ENUMSET1:def 4, NECKLA_2: 2;

          hence thesis by A4, XBOOLE_0:def 5;

        end;

          suppose a1 = 0 & b1 = 2;

          hence thesis by A7, ENUMSET1:def 4;

        end;

          suppose a1 = 0 & b1 = 3;

          hence thesis by A7, ENUMSET1:def 4;

        end;

          suppose a1 = 1 & b1 = 0 ;

          then x in the InternalRel of N4 by A7, ENUMSET1:def 4, NECKLA_2: 2;

          hence thesis by A4, XBOOLE_0:def 5;

        end;

          suppose a1 = 2 & b1 = 0 ;

          hence thesis by A7, ENUMSET1:def 4;

        end;

          suppose a1 = 3 & b1 = 0 ;

          hence thesis by A7, ENUMSET1:def 4;

        end;

          suppose a1 = 1 & b1 = 1;

          hence thesis by A3, A5, A7, RELAT_1:def 10;

        end;

          suppose a1 = 1 & b1 = 2;

          then x in the InternalRel of N4 by A7, ENUMSET1:def 4, NECKLA_2: 2;

          hence thesis by A4, XBOOLE_0:def 5;

        end;

          suppose a1 = 1 & b1 = 3;

          hence thesis by A7, ENUMSET1:def 4;

        end;

          suppose a1 = 2 & b1 = 2;

          hence thesis by A3, A5, A7, RELAT_1:def 10;

        end;

          suppose a1 = 2 & b1 = 1;

          then x in the InternalRel of N4 by A7, ENUMSET1:def 4, NECKLA_2: 2;

          hence thesis by A4, XBOOLE_0:def 5;

        end;

          suppose a1 = 2 & b1 = 3;

          then x in the InternalRel of N4 by A7, ENUMSET1:def 4, NECKLA_2: 2;

          hence thesis by A4, XBOOLE_0:def 5;

        end;

          suppose a1 = 3 & b1 = 3;

          hence thesis by A3, A5, A7, RELAT_1:def 10;

        end;

          suppose a1 = 3 & b1 = 1;

          hence thesis by A7, ENUMSET1:def 4;

        end;

          suppose a1 = 3 & b1 = 2;

          then x in the InternalRel of N4 by A7, ENUMSET1:def 4, NECKLA_2: 2;

          hence thesis by A4, XBOOLE_0:def 5;

        end;

      end;

      let a be object;

      assume

       A8: a in { [ 0 , 2], [2, 0 ], [ 0 , 3], [3, 0 ], [1, 3], [3, 1]};

      per cases by A8, ENUMSET1:def 4;

        suppose

         A9: a = [ 0 , 2];

        

         A10: not a in the InternalRel of N4

        proof

          assume

           A11: not thesis;

          per cases by A11, ENUMSET1:def 4, NECKLA_2: 2;

            suppose a = [ 0 , 1];

            hence contradiction by A9, XTUPLE_0: 1;

          end;

            suppose a = [1, 0 ];

            hence contradiction by A9, XTUPLE_0: 1;

          end;

            suppose a = [1, 2];

            hence contradiction by A9, XTUPLE_0: 1;

          end;

            suppose a = [2, 1];

            hence contradiction by A9, XTUPLE_0: 1;

          end;

            suppose a = [2, 3];

            hence contradiction by A9, XTUPLE_0: 1;

          end;

            suppose a = [3, 2];

            hence contradiction by A9, XTUPLE_0: 1;

          end;

        end;

         0 in cN4 & 2 in cN4 by A1, ENUMSET1:def 2;

        then a in [:cN4, cN4:] by A9, ZFMISC_1: 87;

        then a in ( [:cN4, cN4:] \ the InternalRel of N4) by A10, XBOOLE_0:def 5;

        then

         A12: a in (the InternalRel of N4 ` ) by SUBSET_1:def 4;

         not a in ( id cN4) by A9, RELAT_1:def 10;

        then a in ((the InternalRel of N4 ` ) \ ( id cN4)) by A12, XBOOLE_0:def 5;

        hence thesis by NECKLACE:def 8;

      end;

        suppose

         A13: a = [2, 0 ];

        

         A14: not a in the InternalRel of N4

        proof

          assume

           A15: not thesis;

          per cases by A15, ENUMSET1:def 4, NECKLA_2: 2;

            suppose a = [ 0 , 1];

            hence contradiction by A13, XTUPLE_0: 1;

          end;

            suppose a = [1, 0 ];

            hence contradiction by A13, XTUPLE_0: 1;

          end;

            suppose a = [1, 2];

            hence contradiction by A13, XTUPLE_0: 1;

          end;

            suppose a = [2, 1];

            hence contradiction by A13, XTUPLE_0: 1;

          end;

            suppose a = [2, 3];

            hence contradiction by A13, XTUPLE_0: 1;

          end;

            suppose a = [3, 2];

            hence contradiction by A13, XTUPLE_0: 1;

          end;

        end;

         0 in cN4 & 2 in cN4 by A1, ENUMSET1:def 2;

        then a in [:cN4, cN4:] by A13, ZFMISC_1: 87;

        then a in ( [:cN4, cN4:] \ the InternalRel of N4) by A14, XBOOLE_0:def 5;

        then

         A16: a in (the InternalRel of N4 ` ) by SUBSET_1:def 4;

         not a in ( id cN4) by A13, RELAT_1:def 10;

        then a in ((the InternalRel of N4 ` ) \ ( id cN4)) by A16, XBOOLE_0:def 5;

        hence thesis by NECKLACE:def 8;

      end;

        suppose

         A17: a = [ 0 , 3];

        

         A18: not a in the InternalRel of N4

        proof

          assume

           A19: not thesis;

          per cases by A19, ENUMSET1:def 4, NECKLA_2: 2;

            suppose a = [ 0 , 1];

            hence contradiction by A17, XTUPLE_0: 1;

          end;

            suppose a = [1, 0 ];

            hence contradiction by A17, XTUPLE_0: 1;

          end;

            suppose a = [1, 2];

            hence contradiction by A17, XTUPLE_0: 1;

          end;

            suppose a = [2, 1];

            hence contradiction by A17, XTUPLE_0: 1;

          end;

            suppose a = [2, 3];

            hence contradiction by A17, XTUPLE_0: 1;

          end;

            suppose a = [3, 2];

            hence contradiction by A17, XTUPLE_0: 1;

          end;

        end;

         0 in cN4 & 3 in cN4 by A1, ENUMSET1:def 2;

        then a in [:cN4, cN4:] by A17, ZFMISC_1: 87;

        then a in ( [:cN4, cN4:] \ the InternalRel of N4) by A18, XBOOLE_0:def 5;

        then

         A20: a in (the InternalRel of N4 ` ) by SUBSET_1:def 4;

         not a in ( id cN4) by A17, RELAT_1:def 10;

        then a in ((the InternalRel of N4 ` ) \ ( id cN4)) by A20, XBOOLE_0:def 5;

        hence thesis by NECKLACE:def 8;

      end;

        suppose

         A21: a = [3, 0 ];

        

         A22: not a in the InternalRel of N4

        proof

          assume

           A23: not thesis;

          per cases by A23, ENUMSET1:def 4, NECKLA_2: 2;

            suppose a = [ 0 , 1];

            hence contradiction by A21, XTUPLE_0: 1;

          end;

            suppose a = [1, 0 ];

            hence contradiction by A21, XTUPLE_0: 1;

          end;

            suppose a = [1, 2];

            hence contradiction by A21, XTUPLE_0: 1;

          end;

            suppose a = [2, 1];

            hence contradiction by A21, XTUPLE_0: 1;

          end;

            suppose a = [2, 3];

            hence contradiction by A21, XTUPLE_0: 1;

          end;

            suppose a = [3, 2];

            hence contradiction by A21, XTUPLE_0: 1;

          end;

        end;

         0 in cN4 & 3 in cN4 by A1, ENUMSET1:def 2;

        then a in [:cN4, cN4:] by A21, ZFMISC_1: 87;

        then a in ( [:cN4, cN4:] \ the InternalRel of N4) by A22, XBOOLE_0:def 5;

        then

         A24: a in (the InternalRel of N4 ` ) by SUBSET_1:def 4;

         not a in ( id cN4) by A21, RELAT_1:def 10;

        then a in ((the InternalRel of N4 ` ) \ ( id cN4)) by A24, XBOOLE_0:def 5;

        hence thesis by NECKLACE:def 8;

      end;

        suppose

         A25: a = [1, 3];

        

         A26: not a in the InternalRel of N4

        proof

          assume

           A27: not thesis;

          per cases by A27, ENUMSET1:def 4, NECKLA_2: 2;

            suppose a = [ 0 , 1];

            hence contradiction by A25, XTUPLE_0: 1;

          end;

            suppose a = [1, 0 ];

            hence contradiction by A25, XTUPLE_0: 1;

          end;

            suppose a = [1, 2];

            hence contradiction by A25, XTUPLE_0: 1;

          end;

            suppose a = [2, 1];

            hence contradiction by A25, XTUPLE_0: 1;

          end;

            suppose a = [2, 3];

            hence contradiction by A25, XTUPLE_0: 1;

          end;

            suppose a = [3, 2];

            hence contradiction by A25, XTUPLE_0: 1;

          end;

        end;

        1 in cN4 & 3 in cN4 by A1, ENUMSET1:def 2;

        then a in [:cN4, cN4:] by A25, ZFMISC_1: 87;

        then a in ( [:cN4, cN4:] \ the InternalRel of N4) by A26, XBOOLE_0:def 5;

        then

         A28: a in (the InternalRel of N4 ` ) by SUBSET_1:def 4;

         not a in ( id cN4) by A25, RELAT_1:def 10;

        then a in ((the InternalRel of N4 ` ) \ ( id cN4)) by A28, XBOOLE_0:def 5;

        hence thesis by NECKLACE:def 8;

      end;

        suppose

         A29: a = [3, 1];

        

         A30: not a in the InternalRel of N4

        proof

          assume

           A31: not thesis;

          per cases by A31, ENUMSET1:def 4, NECKLA_2: 2;

            suppose a = [ 0 , 1];

            hence contradiction by A29, XTUPLE_0: 1;

          end;

            suppose a = [1, 0 ];

            hence contradiction by A29, XTUPLE_0: 1;

          end;

            suppose a = [1, 2];

            hence contradiction by A29, XTUPLE_0: 1;

          end;

            suppose a = [2, 1];

            hence contradiction by A29, XTUPLE_0: 1;

          end;

            suppose a = [2, 3];

            hence contradiction by A29, XTUPLE_0: 1;

          end;

            suppose a = [3, 2];

            hence contradiction by A29, XTUPLE_0: 1;

          end;

        end;

        1 in cN4 & 3 in cN4 by A1, ENUMSET1:def 2;

        then a in [:cN4, cN4:] by A29, ZFMISC_1: 87;

        then a in ( [:cN4, cN4:] \ the InternalRel of N4) by A30, XBOOLE_0:def 5;

        then

         A32: a in (the InternalRel of N4 ` ) by SUBSET_1:def 4;

         not a in ( id cN4) by A29, RELAT_1:def 10;

        then a in ((the InternalRel of N4 ` ) \ ( id cN4)) by A32, XBOOLE_0:def 5;

        hence thesis by NECKLACE:def 8;

      end;

    end;

    registration

      let R be RelStr;

      cluster ( ComplRelStr R) -> irreflexive;

      correctness

      proof

        set R1 = ( ComplRelStr R);

        for x be set st x in the carrier of R1 holds not [x, x] in the InternalRel of R1

        proof

          let x be set;

          assume x in the carrier of R1;

          then

           A1: x in the carrier of R by NECKLACE:def 8;

           not [x, x] in the InternalRel of R1

          proof

            assume [x, x] in the InternalRel of R1;

            then [x, x] in ((the InternalRel of R ` ) \ ( id the carrier of R)) by NECKLACE:def 8;

            then not [x, x] in ( id the carrier of R) by XBOOLE_0:def 5;

            hence contradiction by A1, RELAT_1:def 10;

          end;

          hence thesis;

        end;

        hence thesis;

      end;

    end

    registration

      let R be symmetric RelStr;

      cluster ( ComplRelStr R) -> symmetric;

      correctness

      proof

        let x,y be object;

        set S = ( ComplRelStr R);

        assume that

         A1: x in the carrier of S & y in the carrier of S and

         A2: [x, y] in the InternalRel of S;

        per cases ;

          suppose x = y;

          hence thesis by A2;

        end;

          suppose

           A3: x <> y;

          

           A4: x in the carrier of R & y in the carrier of R by A1, NECKLACE:def 8;

          then

           A5: [y, x] in [:the carrier of R, the carrier of R:] by ZFMISC_1: 87;

           [x, y] in ((the InternalRel of R ` ) \ ( id the carrier of R)) by A2, NECKLACE:def 8;

          then [x, y] in (the InternalRel of R ` ) by XBOOLE_0:def 5;

          then [x, y] in ( [:the carrier of R, the carrier of R:] \ the InternalRel of R) by SUBSET_1:def 4;

          then

           A6: not [x, y] in the InternalRel of R by XBOOLE_0:def 5;

          the InternalRel of R is_symmetric_in the carrier of R by NECKLACE:def 3;

          then not [y, x] in the InternalRel of R by A4, A6;

          then [y, x] in ( [:the carrier of R, the carrier of R:] \ the InternalRel of R) by A5, XBOOLE_0:def 5;

          then

           A7: [y, x] in (the InternalRel of R ` ) by SUBSET_1:def 4;

           not [y, x] in ( id the carrier of R) by A3, RELAT_1:def 10;

          then [y, x] in ((the InternalRel of R ` ) \ ( id the carrier of R)) by A7, XBOOLE_0:def 5;

          hence thesis by NECKLACE:def 8;

        end;

      end;

    end

    theorem :: NECKLA_3:12

    

     Th12: for R be RelStr holds the InternalRel of R misses the InternalRel of ( ComplRelStr R)

    proof

      let R be RelStr;

      assume not thesis;

      then (the InternalRel of R /\ the InternalRel of ( ComplRelStr R)) <> {} ;

      then

      consider a be object such that

       A1: a in (the InternalRel of R /\ the InternalRel of ( ComplRelStr R)) by XBOOLE_0:def 1;

      a in the InternalRel of ( ComplRelStr R) by A1, XBOOLE_0:def 4;

      then a in ((the InternalRel of R ` ) \ ( id the carrier of R)) by NECKLACE:def 8;

      then a in (the InternalRel of R ` ) by XBOOLE_0:def 5;

      then a in ( [:the carrier of R, the carrier of R:] \ the InternalRel of R) by SUBSET_1:def 4;

      then not a in the InternalRel of R by XBOOLE_0:def 5;

      hence thesis by A1, XBOOLE_0:def 4;

    end;

    theorem :: NECKLA_3:13

    

     Th13: for R be RelStr holds ( id the carrier of R) misses the InternalRel of ( ComplRelStr R)

    proof

      let R be RelStr;

      assume not thesis;

      then (( id the carrier of R) /\ the InternalRel of ( ComplRelStr R)) <> {} ;

      then

      consider a be object such that

       A1: a in (( id the carrier of R) /\ the InternalRel of ( ComplRelStr R)) by XBOOLE_0:def 1;

      a in the InternalRel of ( ComplRelStr R) by A1, XBOOLE_0:def 4;

      then

       A2: a in ((the InternalRel of R ` ) \ ( id the carrier of R)) by NECKLACE:def 8;

      a in ( id the carrier of R) by A1, XBOOLE_0:def 4;

      hence contradiction by A2, XBOOLE_0:def 5;

    end;

    theorem :: NECKLA_3:14

    

     Th14: for G be RelStr holds [:the carrier of G, the carrier of G:] = ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of ( ComplRelStr G))

    proof

      let G be RelStr;

      set idcG = ( id the carrier of G), IG = the InternalRel of G, ICmpG = the InternalRel of ( ComplRelStr G), cG = the carrier of G;

      thus [:cG, cG:] c= ((idcG \/ IG) \/ ICmpG)

      proof

        let a be object;

        assume

         A1: a in [:cG, cG:];

        then

        consider x,y be object such that

         A2: x in cG and y in cG and

         A3: a = [x, y] by ZFMISC_1:def 2;

        per cases ;

          suppose

           A4: x = y;

           [x, x] in ( id cG) by A2, RELAT_1:def 10;

          then a in (( id cG) \/ IG) by A3, A4, XBOOLE_0:def 3;

          hence thesis by XBOOLE_0:def 3;

        end;

          suppose x <> y;

          then

           A5: not a in ( id cG) by A3, RELAT_1:def 10;

          thus thesis

          proof

            per cases ;

              suppose a in IG;

              then a in (( id cG) \/ IG) by XBOOLE_0:def 3;

              hence thesis by XBOOLE_0:def 3;

            end;

              suppose not a in IG;

              then a in ( [:cG, cG:] \ IG) by A1, XBOOLE_0:def 5;

              then a in (IG ` ) by SUBSET_1:def 4;

              then a in ((IG ` ) \ ( id cG)) by A5, XBOOLE_0:def 5;

              then a in ICmpG by NECKLACE:def 8;

              then a in (IG \/ ICmpG) by XBOOLE_0:def 3;

              then a in (( id cG) \/ (IG \/ ICmpG)) by XBOOLE_0:def 3;

              hence thesis by XBOOLE_1: 4;

            end;

          end;

        end;

      end;

      let a be object;

      assume a in ((idcG \/ IG) \/ ICmpG);

      then

       A6: a in (( id cG) \/ IG) or a in ICmpG by XBOOLE_0:def 3;

      per cases by A6, XBOOLE_0:def 3;

        suppose a in ( id cG);

        hence thesis;

      end;

        suppose a in IG;

        hence thesis;

      end;

        suppose a in ICmpG;

        then a in ((IG ` ) \ ( id cG)) by NECKLACE:def 8;

        hence thesis;

      end;

    end;

    theorem :: NECKLA_3:15

    

     Th15: for G be strict irreflexive RelStr st G is trivial holds ( ComplRelStr G) = G

    proof

      let G be strict irreflexive RelStr;

      set CG = ( ComplRelStr G);

      assume

       A1: G is trivial;

      per cases by A1, ZFMISC_1: 131;

        suppose

         A2: the carrier of G is empty;

        the InternalRel of CG = ((the InternalRel of G ` ) \ ( id the carrier of G)) by NECKLACE:def 8;

        then

         A3: the InternalRel of CG = (( {} \ {} ) \ ( id {} )) by A2;

        the InternalRel of G = {} by A2;

        hence thesis by A3, NECKLACE:def 8;

      end;

        suppose ex x be object st the carrier of G = {x};

        then

        consider x be object such that

         A4: the carrier of G = {x};

        

         A5: the carrier of CG = {x} by A4, NECKLACE:def 8;

        the InternalRel of G c= [: {x}, {x}:] by A4;

        then the InternalRel of G c= { [x, x]} by ZFMISC_1: 29;

        then

         A6: the InternalRel of G = {} or the InternalRel of G = { [x, x]} by ZFMISC_1: 33;

        

         A7: the InternalRel of G <> { [x, x]}

        proof

          assume not thesis;

          then

           A8: [x, x] in the InternalRel of G by TARSKI:def 1;

          x in the carrier of G by A4, TARSKI:def 1;

          hence contradiction by A8, NECKLACE:def 5;

        end;

        the InternalRel of CG = ((the InternalRel of G ` ) \ ( id the carrier of G)) by NECKLACE:def 8;

        then the InternalRel of CG = (( [: {x}, {x}:] \ {} ) \ ( id {x})) by A4, A6, A7, SUBSET_1:def 4;

        then the InternalRel of CG = ( { [x, x]} \ ( id {x})) by ZFMISC_1: 29;

        then the InternalRel of CG = ( { [x, x]} \ { [x, x]}) by SYSREL: 13;

        hence thesis by A4, A6, A7, A5, XBOOLE_1: 37;

      end;

    end;

    theorem :: NECKLA_3:16

    

     Th16: for G be strict irreflexive RelStr holds ( ComplRelStr ( ComplRelStr G)) = G

    proof

      let G be strict irreflexive RelStr;

      set CCmpG = ( ComplRelStr ( ComplRelStr G)), CmpG = ( ComplRelStr G), cG = the carrier of G, IG = the InternalRel of G, ICmpG = the InternalRel of CmpG, ICCmpG = the InternalRel of CCmpG;

      

       A1: cG = the carrier of CmpG by NECKLACE:def 8

      .= the carrier of CCmpG by NECKLACE:def 8;

      

       A2: cG = the carrier of CmpG by NECKLACE:def 8;

      

       A3: ( id cG) misses IG

      proof

        assume not thesis;

        then (( id cG) /\ IG) <> {} ;

        then

        consider a be object such that

         A4: a in (( id cG) /\ IG) by XBOOLE_0:def 1;

        

         A5: a in IG by A4, XBOOLE_0:def 4;

        consider x,y be object such that

         A6: a = [x, y] and

         A7: x in cG and y in cG by A4, RELSET_1: 2;

        a in ( id cG) by A4, XBOOLE_0:def 4;

        then x = y by A6, RELAT_1:def 10;

        hence contradiction by A5, A6, A7, NECKLACE:def 5;

      end;

      ICCmpG = ((ICmpG ` ) \ ( id the carrier of CmpG)) by NECKLACE:def 8

      .= (( [:the carrier of CmpG, the carrier of CmpG:] \ ICmpG) \ ( id the carrier of CmpG)) by SUBSET_1:def 4

      .= (( [:cG, cG:] \ ((IG ` ) \ ( id cG))) \ ( id cG)) by A2, NECKLACE:def 8

      .= ((( [:cG, cG:] \ (IG ` )) \/ ( [:cG, cG:] /\ ( id cG))) \ ( id cG)) by XBOOLE_1: 52

      .= ((( [:cG, cG:] \ (IG ` )) \/ ( id cG)) \ ( id cG)) by XBOOLE_1: 28

      .= (( [:cG, cG:] \ (IG ` )) \ ( id cG)) by XBOOLE_1: 40

      .= (( [:cG, cG:] \ ( [:cG, cG:] \ IG)) \ ( id cG)) by SUBSET_1:def 4

      .= (( [:cG, cG:] /\ IG) \ ( id cG)) by XBOOLE_1: 48

      .= (IG \ ( id cG)) by XBOOLE_1: 28

      .= IG by A3, XBOOLE_1: 83;

      hence thesis by A1;

    end;

    theorem :: NECKLA_3:17

    

     Th17: for G1,G2 be RelStr st the carrier of G1 misses the carrier of G2 holds ( ComplRelStr ( union_of (G1,G2))) = ( sum_of (( ComplRelStr G1),( ComplRelStr G2)))

    proof

      let G1,G2 be RelStr;

      

       A1: the carrier of ( sum_of (( ComplRelStr G1),( ComplRelStr G2))) = (the carrier of ( ComplRelStr G1) \/ the carrier of ( ComplRelStr G2)) by NECKLA_2:def 3

      .= (the carrier of G1 \/ the carrier of ( ComplRelStr G2)) by NECKLACE:def 8

      .= (the carrier of G1 \/ the carrier of G2) by NECKLACE:def 8;

      set P = the InternalRel of ( ComplRelStr ( union_of (G1,G2))), R = the InternalRel of ( sum_of (( ComplRelStr G1),( ComplRelStr G2))), X1 = the InternalRel of ( ComplRelStr G1), X2 = the InternalRel of ( ComplRelStr G2), X3 = [:the carrier of ( ComplRelStr G1), the carrier of ( ComplRelStr G2):], X4 = [:the carrier of ( ComplRelStr G2), the carrier of ( ComplRelStr G1):], X5 = [:the carrier of G1, the carrier of G1:], X6 = [:the carrier of G2, the carrier of G2:], X7 = [:the carrier of G1, the carrier of G2:], X8 = [:the carrier of G2, the carrier of G1:];

      assume

       A2: the carrier of G1 misses the carrier of G2;

      

       A3: for a,b be object holds [a, b] in P iff [a, b] in R

      proof

        let a,b be object;

        set x = [a, b];

        thus x in P implies x in R

        proof

          assume x in P;

          then

           A4: x in ((the InternalRel of ( union_of (G1,G2)) ` ) \ ( id the carrier of ( union_of (G1,G2)))) by NECKLACE:def 8;

          then x in [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):];

          then x in [:(the carrier of G1 \/ the carrier of G2), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then

           A5: x in [:(the carrier of G1 \/ the carrier of G2), (the carrier of G1 \/ the carrier of G2):] by NECKLA_2:def 2;

           not x in ( id the carrier of ( union_of (G1,G2))) by A4, XBOOLE_0:def 5;

          then

           A6: not x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 2;

          

           A7: not x in ( id the carrier of G1) & not x in ( id the carrier of G2)

          proof

            assume not thesis;

            then x in (( id the carrier of G1) \/ ( id the carrier of G2)) by XBOOLE_0:def 3;

            hence contradiction by A6, SYSREL: 14;

          end;

          the carrier of G1 = the carrier of ( ComplRelStr G1) & the carrier of G2 = the carrier of ( ComplRelStr G2) by NECKLACE:def 8;

          then x in (((X5 \/ X3) \/ X4) \/ X6) by A5, ZFMISC_1: 98;

          then x in (X5 \/ ((X3 \/ X4) \/ X6)) by XBOOLE_1: 113;

          then x in X5 or x in ((X3 \/ X4) \/ X6) by XBOOLE_0:def 3;

          then x in X5 or x in (X3 \/ (X4 \/ X6)) by XBOOLE_1: 4;

          then

           A8: x in X5 or x in X3 or x in (X4 \/ X6) by XBOOLE_0:def 3;

          x in (the InternalRel of ( union_of (G1,G2)) ` ) by A4, XBOOLE_0:def 5;

          then x in ( [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] \ the InternalRel of ( union_of (G1,G2))) by SUBSET_1:def 4;

          then not x in the InternalRel of ( union_of (G1,G2)) by XBOOLE_0:def 5;

          then

           A9: not x in (the InternalRel of G1 \/ the InternalRel of G2) by NECKLA_2:def 2;

          then

           A10: not x in the InternalRel of G1 by XBOOLE_0:def 3;

          

           A11: not x in the InternalRel of G2 by A9, XBOOLE_0:def 3;

          per cases by A8, XBOOLE_0:def 3;

            suppose x in [:the carrier of G1, the carrier of G1:];

            then x in ( [:the carrier of G1, the carrier of G1:] \ the InternalRel of G1) by A10, XBOOLE_0:def 5;

            then x in (the InternalRel of G1 ` ) by SUBSET_1:def 4;

            then x in ((the InternalRel of G1 ` ) \ ( id the carrier of G1)) by A7, XBOOLE_0:def 5;

            then x in X1 by NECKLACE:def 8;

            then x in (X1 \/ ((X2 \/ X3) \/ X4)) by XBOOLE_0:def 3;

            then x in (((X1 \/ X2) \/ X3) \/ X4) by XBOOLE_1: 113;

            hence thesis by NECKLA_2:def 3;

          end;

            suppose x in X3;

            then x in (X2 \/ X3) by XBOOLE_0:def 3;

            then x in ((X2 \/ X3) \/ X4) by XBOOLE_0:def 3;

            then x in (X1 \/ ((X2 \/ X3) \/ X4)) by XBOOLE_0:def 3;

            then x in (((X1 \/ X2) \/ X3) \/ X4) by XBOOLE_1: 113;

            hence thesis by NECKLA_2:def 3;

          end;

            suppose x in X4;

            then x in (X3 \/ X4) by XBOOLE_0:def 3;

            then x in (X2 \/ (X3 \/ X4)) by XBOOLE_0:def 3;

            then x in ((X2 \/ X3) \/ X4) by XBOOLE_1: 4;

            then x in (X1 \/ ((X2 \/ X3) \/ X4)) by XBOOLE_0:def 3;

            then x in (((X1 \/ X2) \/ X3) \/ X4) by XBOOLE_1: 113;

            hence thesis by NECKLA_2:def 3;

          end;

            suppose x in [:the carrier of G2, the carrier of G2:];

            then x in ( [:the carrier of G2, the carrier of G2:] \ the InternalRel of G2) by A11, XBOOLE_0:def 5;

            then x in (the InternalRel of G2 ` ) by SUBSET_1:def 4;

            then x in ((the InternalRel of G2 ` ) \ ( id the carrier of G2)) by A7, XBOOLE_0:def 5;

            then x in the InternalRel of ( ComplRelStr G2) by NECKLACE:def 8;

            then x in (the InternalRel of ( ComplRelStr G1) \/ the InternalRel of ( ComplRelStr G2)) by XBOOLE_0:def 3;

            then x in ((the InternalRel of ( ComplRelStr G1) \/ the InternalRel of ( ComplRelStr G2)) \/ [:the carrier of ( ComplRelStr G1), the carrier of ( ComplRelStr G2):]) by XBOOLE_0:def 3;

            then x in (((the InternalRel of ( ComplRelStr G1) \/ the InternalRel of ( ComplRelStr G2)) \/ [:the carrier of ( ComplRelStr G1), the carrier of ( ComplRelStr G2):]) \/ [:the carrier of ( ComplRelStr G2), the carrier of ( ComplRelStr G1):]) by XBOOLE_0:def 3;

            hence thesis by NECKLA_2:def 3;

          end;

        end;

        assume x in R;

        then x in (((X1 \/ X2) \/ X3) \/ X4) by NECKLA_2:def 3;

        then x in ((X1 \/ X2) \/ X3) or x in X4 by XBOOLE_0:def 3;

        then

         A12: x in (X1 \/ X2) or x in X3 or x in X4 by XBOOLE_0:def 3;

        per cases by A12, XBOOLE_0:def 3;

          suppose x in X1;

          then

           A13: x in ((the InternalRel of G1 ` ) \ ( id the carrier of G1)) by NECKLACE:def 8;

          then x in (the InternalRel of G1 ` ) by XBOOLE_0:def 5;

          then x in ( [:the carrier of G1, the carrier of G1:] \ the InternalRel of G1) by SUBSET_1:def 4;

          then

           A14: not x in the InternalRel of G1 by XBOOLE_0:def 5;

          

           A15: not x in the InternalRel of ( union_of (G1,G2))

          proof

            assume not thesis;

            then x in (the InternalRel of G1 \/ the InternalRel of G2) by NECKLA_2:def 2;

            then x in the InternalRel of G2 by A14, XBOOLE_0:def 3;

            then ( [:the carrier of G1, the carrier of G1:] /\ [:the carrier of G2, the carrier of G2:]) is non empty by A13, XBOOLE_0:def 4;

            then [:the carrier of G1, the carrier of G1:] meets [:the carrier of G2, the carrier of G2:];

            hence contradiction by A2, ZFMISC_1: 104;

          end;

          

           A16: not x in ( id the carrier of ( union_of (G1,G2)))

          proof

            assume not thesis;

            then x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 2;

            then

             A17: x in (( id the carrier of G1) \/ ( id the carrier of G2)) by SYSREL: 14;

            thus thesis

            proof

              per cases by A17, XBOOLE_0:def 3;

                suppose x in ( id the carrier of G1);

                hence contradiction by A13, XBOOLE_0:def 5;

              end;

                suppose x in ( id the carrier of G2);

                then ( [:the carrier of G1, the carrier of G1:] /\ [:the carrier of G2, the carrier of G2:]) is non empty by A13, XBOOLE_0:def 4;

                then [:the carrier of G1, the carrier of G1:] meets [:the carrier of G2, the carrier of G2:];

                hence contradiction by A2, ZFMISC_1: 104;

              end;

            end;

          end;

          x in (X5 \/ X7) by A13, XBOOLE_0:def 3;

          then x in ((X5 \/ X7) \/ X8) by XBOOLE_0:def 3;

          then x in (((X5 \/ X7) \/ X8) \/ X6) by XBOOLE_0:def 3;

          then x in [:(the carrier of G1 \/ the carrier of G2), (the carrier of G1 \/ the carrier of G2):] by ZFMISC_1: 98;

          then x in [:(the carrier of G1 \/ the carrier of G2), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in ( [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] \ the InternalRel of ( union_of (G1,G2))) by A15, XBOOLE_0:def 5;

          then x in (the InternalRel of ( union_of (G1,G2)) ` ) by SUBSET_1:def 4;

          then x in ((the InternalRel of ( union_of (G1,G2)) ` ) \ ( id the carrier of ( union_of (G1,G2)))) by A16, XBOOLE_0:def 5;

          hence thesis by NECKLACE:def 8;

        end;

          suppose x in X2;

          then

           A18: x in ((the InternalRel of G2 ` ) \ ( id the carrier of G2)) by NECKLACE:def 8;

          then x in (the InternalRel of G2 ` ) by XBOOLE_0:def 5;

          then x in ( [:the carrier of G2, the carrier of G2:] \ the InternalRel of G2) by SUBSET_1:def 4;

          then

           A19: not x in the InternalRel of G2 by XBOOLE_0:def 5;

          

           A20: not x in the InternalRel of ( union_of (G1,G2))

          proof

            assume not thesis;

            then x in (the InternalRel of G1 \/ the InternalRel of G2) by NECKLA_2:def 2;

            then x in the InternalRel of G1 by A19, XBOOLE_0:def 3;

            then ( [:the carrier of G1, the carrier of G1:] /\ [:the carrier of G2, the carrier of G2:]) is non empty by A18, XBOOLE_0:def 4;

            then [:the carrier of G1, the carrier of G1:] meets [:the carrier of G2, the carrier of G2:];

            hence contradiction by A2, ZFMISC_1: 104;

          end;

          

           A21: not x in ( id the carrier of ( union_of (G1,G2)))

          proof

            assume not thesis;

            then x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 2;

            then

             A22: x in (( id the carrier of G1) \/ ( id the carrier of G2)) by SYSREL: 14;

            per cases by A22, XBOOLE_0:def 3;

              suppose x in ( id the carrier of G2);

              hence contradiction by A18, XBOOLE_0:def 5;

            end;

              suppose x in ( id the carrier of G1);

              then ( [:the carrier of G1, the carrier of G1:] /\ [:the carrier of G2, the carrier of G2:]) is non empty by A18, XBOOLE_0:def 4;

              then [:the carrier of G1, the carrier of G1:] meets [:the carrier of G2, the carrier of G2:];

              hence contradiction by A2, ZFMISC_1: 104;

            end;

          end;

          x in (X8 \/ X6) by A18, XBOOLE_0:def 3;

          then x in (X7 \/ (X8 \/ X6)) by XBOOLE_0:def 3;

          then x in ((X7 \/ X8) \/ X6) by XBOOLE_1: 4;

          then x in (X5 \/ ((X7 \/ X8) \/ X6)) by XBOOLE_0:def 3;

          then x in (((X5 \/ X7) \/ X8) \/ X6) by XBOOLE_1: 113;

          then x in [:(the carrier of G1 \/ the carrier of G2), (the carrier of G1 \/ the carrier of G2):] by ZFMISC_1: 98;

          then x in [:(the carrier of G1 \/ the carrier of G2), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in ( [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] \ the InternalRel of ( union_of (G1,G2))) by A20, XBOOLE_0:def 5;

          then x in (the InternalRel of ( union_of (G1,G2)) ` ) by SUBSET_1:def 4;

          then x in ((the InternalRel of ( union_of (G1,G2)) ` ) \ ( id the carrier of ( union_of (G1,G2)))) by A21, XBOOLE_0:def 5;

          hence thesis by NECKLACE:def 8;

        end;

          suppose x in X3;

          then

           A23: x in [:the carrier of G1, the carrier of ( ComplRelStr G2):] by NECKLACE:def 8;

          then

           A24: x in [:the carrier of G1, the carrier of G2:] by NECKLACE:def 8;

          

           A25: not x in the InternalRel of ( union_of (G1,G2))

          proof

            assume not thesis;

            then

             A26: x in (the InternalRel of G1 \/ the InternalRel of G2) by NECKLA_2:def 2;

            per cases by A26, XBOOLE_0:def 3;

              suppose

               A27: x in the InternalRel of G1;

              

               A28: b in the carrier of G2 by A24, ZFMISC_1: 87;

              b in the carrier of G1 by A27, ZFMISC_1: 87;

              then b in (the carrier of G1 /\ the carrier of G2) by A28, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

              suppose

               A29: x in the InternalRel of G2;

              

               A30: a in the carrier of G1 by A23, ZFMISC_1: 87;

              a in the carrier of G2 by A29, ZFMISC_1: 87;

              then a in (the carrier of G1 /\ the carrier of G2) by A30, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

          end;

          

           A31: not x in ( id the carrier of ( union_of (G1,G2)))

          proof

            assume not thesis;

            then x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 2;

            then

             A32: x in (( id the carrier of G1) \/ ( id the carrier of G2)) by SYSREL: 14;

            per cases by A32, XBOOLE_0:def 3;

              suppose

               A33: x in ( id the carrier of G1);

              

               A34: b in the carrier of G2 by A24, ZFMISC_1: 87;

              b in the carrier of G1 by A33, ZFMISC_1: 87;

              then b in (the carrier of G1 /\ the carrier of G2) by A34, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

              suppose

               A35: x in ( id the carrier of G2);

              

               A36: a in the carrier of G1 by A23, ZFMISC_1: 87;

              a in the carrier of G2 by A35, ZFMISC_1: 87;

              then a in (the carrier of G1 /\ the carrier of G2) by A36, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

          end;

          x in (X7 \/ X8) by A24, XBOOLE_0:def 3;

          then x in (X5 \/ (X7 \/ X8)) by XBOOLE_0:def 3;

          then x in ((X5 \/ X7) \/ X8) by XBOOLE_1: 4;

          then x in (((X5 \/ X7) \/ X8) \/ X6) by XBOOLE_0:def 3;

          then x in [:(the carrier of G1 \/ the carrier of G2), (the carrier of G1 \/ the carrier of G2):] by ZFMISC_1: 98;

          then x in [:(the carrier of G1 \/ the carrier of G2), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in ( [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] \ the InternalRel of ( union_of (G1,G2))) by A25, XBOOLE_0:def 5;

          then x in (the InternalRel of ( union_of (G1,G2)) ` ) by SUBSET_1:def 4;

          then x in ((the InternalRel of ( union_of (G1,G2)) ` ) \ ( id the carrier of ( union_of (G1,G2)))) by A31, XBOOLE_0:def 5;

          hence thesis by NECKLACE:def 8;

        end;

          suppose x in X4;

          then

           A37: x in [:the carrier of G2, the carrier of ( ComplRelStr G1):] by NECKLACE:def 8;

          then

           A38: x in [:the carrier of G2, the carrier of G1:] by NECKLACE:def 8;

          

           A39: not x in the InternalRel of ( union_of (G1,G2))

          proof

            assume not thesis;

            then

             A40: x in (the InternalRel of G1 \/ the InternalRel of G2) by NECKLA_2:def 2;

            per cases by A40, XBOOLE_0:def 3;

              suppose

               A41: x in the InternalRel of G1;

              

               A42: a in the carrier of G2 by A37, ZFMISC_1: 87;

              a in the carrier of G1 by A41, ZFMISC_1: 87;

              then a in (the carrier of G1 /\ the carrier of G2) by A42, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

              suppose

               A43: x in the InternalRel of G2;

              

               A44: b in the carrier of G1 by A38, ZFMISC_1: 87;

              b in the carrier of G2 by A43, ZFMISC_1: 87;

              then b in (the carrier of G1 /\ the carrier of G2) by A44, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

          end;

          

           A45: not x in ( id the carrier of ( union_of (G1,G2)))

          proof

            assume not thesis;

            then x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 2;

            then

             A46: x in (( id the carrier of G1) \/ ( id the carrier of G2)) by SYSREL: 14;

            per cases by A46, XBOOLE_0:def 3;

              suppose

               A47: x in ( id the carrier of G1);

              

               A48: a in the carrier of G2 by A37, ZFMISC_1: 87;

              a in the carrier of G1 by A47, ZFMISC_1: 87;

              then a in (the carrier of G1 /\ the carrier of G2) by A48, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

              suppose

               A49: x in ( id the carrier of G2);

              

               A50: b in the carrier of G1 by A38, ZFMISC_1: 87;

              b in the carrier of G2 by A49, ZFMISC_1: 87;

              then b in (the carrier of G1 /\ the carrier of G2) by A50, XBOOLE_0:def 4;

              hence contradiction by A2;

            end;

          end;

          x in (X7 \/ X8) by A38, XBOOLE_0:def 3;

          then x in (X5 \/ (X7 \/ X8)) by XBOOLE_0:def 3;

          then x in ((X5 \/ X7) \/ X8) by XBOOLE_1: 4;

          then x in (((X5 \/ X7) \/ X8) \/ X6) by XBOOLE_0:def 3;

          then x in [:(the carrier of G1 \/ the carrier of G2), (the carrier of G1 \/ the carrier of G2):] by ZFMISC_1: 98;

          then x in [:(the carrier of G1 \/ the carrier of G2), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] by NECKLA_2:def 2;

          then x in ( [:the carrier of ( union_of (G1,G2)), the carrier of ( union_of (G1,G2)):] \ the InternalRel of ( union_of (G1,G2))) by A39, XBOOLE_0:def 5;

          then x in (the InternalRel of ( union_of (G1,G2)) ` ) by SUBSET_1:def 4;

          then x in ((the InternalRel of ( union_of (G1,G2)) ` ) \ ( id the carrier of ( union_of (G1,G2)))) by A45, XBOOLE_0:def 5;

          hence thesis by NECKLACE:def 8;

        end;

      end;

      the carrier of ( ComplRelStr ( union_of (G1,G2))) = the carrier of ( union_of (G1,G2)) by NECKLACE:def 8

      .= (the carrier of G1 \/ the carrier of G2) by NECKLA_2:def 2;

      hence thesis by A1, A3, RELAT_1:def 2;

    end;

    theorem :: NECKLA_3:18

    

     Th18: for G1,G2 be RelStr st the carrier of G1 misses the carrier of G2 holds ( ComplRelStr ( sum_of (G1,G2))) = ( union_of (( ComplRelStr G1),( ComplRelStr G2)))

    proof

      let G1,G2 be RelStr;

      assume

       A1: the carrier of G1 misses the carrier of G2;

      set P = the InternalRel of ( ComplRelStr ( sum_of (G1,G2))), R = the InternalRel of ( union_of (( ComplRelStr G1),( ComplRelStr G2))), X1 = the InternalRel of ( ComplRelStr G1), X2 = the InternalRel of ( ComplRelStr G2), X5 = [:the carrier of G1, the carrier of G1:], X6 = [:the carrier of G2, the carrier of G2:], X7 = [:the carrier of G1, the carrier of G2:], X8 = [:the carrier of G2, the carrier of G1:];

      

       A2: [:the carrier of ( sum_of (G1,G2)), the carrier of ( sum_of (G1,G2)):] = [:(the carrier of G1 \/ the carrier of G2), the carrier of ( sum_of (G1,G2)):] by NECKLA_2:def 3

      .= [:(the carrier of G1 \/ the carrier of G2), (the carrier of G1 \/ the carrier of G2):] by NECKLA_2:def 3

      .= (((X5 \/ X7) \/ X8) \/ X6) by ZFMISC_1: 98;

      

       A3: for a,b be object holds [a, b] in P iff [a, b] in R

      proof

        let a,b be object;

        set x = [a, b];

        thus x in P implies x in R

        proof

          assume x in P;

          then

           A4: x in ((the InternalRel of ( sum_of (G1,G2)) ` ) \ ( id the carrier of ( sum_of (G1,G2)))) by NECKLACE:def 8;

          then x in ((X5 \/ X7) \/ X8) or x in X6 by A2, XBOOLE_0:def 3;

          then

           A5: x in (X5 \/ X7) or x in X8 or x in X6 by XBOOLE_0:def 3;

          x in (the InternalRel of ( sum_of (G1,G2)) ` ) by A4, XBOOLE_0:def 5;

          then x in ( [:the carrier of ( sum_of (G1,G2)), the carrier of ( sum_of (G1,G2)):] \ the InternalRel of ( sum_of (G1,G2))) by SUBSET_1:def 4;

          then not x in the InternalRel of ( sum_of (G1,G2)) by XBOOLE_0:def 5;

          then

           A6: not x in (((the InternalRel of G1 \/ the InternalRel of G2) \/ [:the carrier of G1, the carrier of G2:]) \/ [:the carrier of G2, the carrier of G1:]) by NECKLA_2:def 3;

          

           A7: not x in the InternalRel of G1 & not x in the InternalRel of G2 & not x in [:the carrier of G1, the carrier of G2:] & not x in [:the carrier of G2, the carrier of G1:]

          proof

            assume not thesis;

            then x in (the InternalRel of G1 \/ the InternalRel of G2) or x in [:the carrier of G1, the carrier of G2:] or x in [:the carrier of G2, the carrier of G1:] by XBOOLE_0:def 3;

            then x in ((the InternalRel of G1 \/ the InternalRel of G2) \/ [:the carrier of G1, the carrier of G2:]) or x in [:the carrier of G2, the carrier of G1:] by XBOOLE_0:def 3;

            hence contradiction by A6, XBOOLE_0:def 3;

          end;

           not x in ( id the carrier of ( sum_of (G1,G2))) by A4, XBOOLE_0:def 5;

          then not x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 3;

          then

           A8: not x in (( id the carrier of G1) \/ ( id the carrier of G2)) by SYSREL: 14;

          then

           A9: not x in ( id the carrier of G1) by XBOOLE_0:def 3;

          

           A10: not x in ( id the carrier of G2) by A8, XBOOLE_0:def 3;

          per cases by A5, XBOOLE_0:def 3;

            suppose x in X5;

            then x in (X5 \ the InternalRel of G1) by A7, XBOOLE_0:def 5;

            then x in (the InternalRel of G1 ` ) by SUBSET_1:def 4;

            then x in ((the InternalRel of G1 ` ) \ ( id the carrier of G1)) by A9, XBOOLE_0:def 5;

            then x in X1 by NECKLACE:def 8;

            then x in (X1 \/ X2) by XBOOLE_0:def 3;

            hence thesis by NECKLA_2:def 2;

          end;

            suppose x in X7;

            hence thesis by A7;

          end;

            suppose x in X8;

            hence thesis by A7;

          end;

            suppose x in X6;

            then x in (X6 \ the InternalRel of G2) by A7, XBOOLE_0:def 5;

            then x in (the InternalRel of G2 ` ) by SUBSET_1:def 4;

            then x in ((the InternalRel of G2 ` ) \ ( id the carrier of G2)) by A10, XBOOLE_0:def 5;

            then x in X2 by NECKLACE:def 8;

            then x in (X1 \/ X2) by XBOOLE_0:def 3;

            hence thesis by NECKLA_2:def 2;

          end;

        end;

        assume x in R;

        then

         A11: x in (the InternalRel of ( ComplRelStr G1) \/ the InternalRel of ( ComplRelStr G2)) by NECKLA_2:def 2;

        per cases by A11, XBOOLE_0:def 3;

          suppose x in the InternalRel of ( ComplRelStr G1);

          then

           A12: x in ((the InternalRel of G1 ` ) \ ( id the carrier of G1)) by NECKLACE:def 8;

          then

           A13: not x in ( id the carrier of G1) by XBOOLE_0:def 5;

          

           A14: not x in ( id the carrier of ( sum_of (G1,G2)))

          proof

            assume not thesis;

            then x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 3;

            then x in (( id the carrier of G1) \/ ( id the carrier of G2)) by SYSREL: 14;

            then x in ( id the carrier of G2) by A13, XBOOLE_0:def 3;

            then

             A15: a in the carrier of G2 by ZFMISC_1: 87;

            a in the carrier of G1 by A12, ZFMISC_1: 87;

            then (the carrier of G1 /\ the carrier of G2) is non empty by A15, XBOOLE_0:def 4;

            hence contradiction by A1;

          end;

          x in (the InternalRel of G1 ` ) by A12, XBOOLE_0:def 5;

          then x in ( [:the carrier of G1, the carrier of G1:] \ the InternalRel of G1) by SUBSET_1:def 4;

          then

           A16: not x in the InternalRel of G1 by XBOOLE_0:def 5;

          

           A17: not x in the InternalRel of ( sum_of (G1,G2))

          proof

            assume not thesis;

            then x in (((the InternalRel of G1 \/ the InternalRel of G2) \/ X7) \/ X8) by NECKLA_2:def 3;

            then x in ((the InternalRel of G1 \/ the InternalRel of G2) \/ X7) or x in X8 by XBOOLE_0:def 3;

            then

             A18: x in (the InternalRel of G1 \/ the InternalRel of G2) or x in X7 or x in X8 by XBOOLE_0:def 3;

            per cases by A16, A18, XBOOLE_0:def 3;

              suppose

               A19: x in the InternalRel of G2;

              

               A20: a in the carrier of G1 by A12, ZFMISC_1: 87;

              a in the carrier of G2 by A19, ZFMISC_1: 87;

              then (the carrier of G1 /\ the carrier of G2) is non empty by A20, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose

               A21: x in X7;

              

               A22: b in the carrier of G1 by A12, ZFMISC_1: 87;

              b in the carrier of G2 by A21, ZFMISC_1: 87;

              then (the carrier of G1 /\ the carrier of G2) is non empty by A22, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose

               A23: x in X8;

              

               A24: a in the carrier of G1 by A12, ZFMISC_1: 87;

              a in the carrier of G2 by A23, ZFMISC_1: 87;

              then (the carrier of G1 /\ the carrier of G2) is non empty by A24, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

          end;

          x in (X5 \/ ((X7 \/ X8) \/ X6)) by A12, XBOOLE_0:def 3;

          then x in [:the carrier of ( sum_of (G1,G2)), the carrier of ( sum_of (G1,G2)):] by A2, XBOOLE_1: 113;

          then x in ( [:the carrier of ( sum_of (G1,G2)), the carrier of ( sum_of (G1,G2)):] \ the InternalRel of ( sum_of (G1,G2))) by A17, XBOOLE_0:def 5;

          then x in (the InternalRel of ( sum_of (G1,G2)) ` ) by SUBSET_1:def 4;

          then x in ((the InternalRel of ( sum_of (G1,G2)) ` ) \ ( id the carrier of ( sum_of (G1,G2)))) by A14, XBOOLE_0:def 5;

          hence thesis by NECKLACE:def 8;

        end;

          suppose x in the InternalRel of ( ComplRelStr G2);

          then

           A25: x in ((the InternalRel of G2 ` ) \ ( id the carrier of G2)) by NECKLACE:def 8;

          then

           A26: not x in ( id the carrier of G2) by XBOOLE_0:def 5;

          

           A27: not x in ( id the carrier of ( sum_of (G1,G2)))

          proof

            assume not thesis;

            then x in ( id (the carrier of G1 \/ the carrier of G2)) by NECKLA_2:def 3;

            then x in (( id the carrier of G1) \/ ( id the carrier of G2)) by SYSREL: 14;

            then x in ( id the carrier of G1) by A26, XBOOLE_0:def 3;

            then

             A28: b in the carrier of G1 by ZFMISC_1: 87;

            b in the carrier of G2 by A25, ZFMISC_1: 87;

            then (the carrier of G1 /\ the carrier of G2) is non empty by A28, XBOOLE_0:def 4;

            hence contradiction by A1;

          end;

          x in (the InternalRel of G2 ` ) by A25, XBOOLE_0:def 5;

          then x in ( [:the carrier of G2, the carrier of G2:] \ the InternalRel of G2) by SUBSET_1:def 4;

          then

           A29: not x in the InternalRel of G2 by XBOOLE_0:def 5;

          

           A30: not x in the InternalRel of ( sum_of (G1,G2))

          proof

            assume not thesis;

            then x in (((the InternalRel of G1 \/ the InternalRel of G2) \/ X7) \/ X8) by NECKLA_2:def 3;

            then x in ((the InternalRel of G1 \/ the InternalRel of G2) \/ X7) or x in X8 by XBOOLE_0:def 3;

            then

             A31: x in (the InternalRel of G1 \/ the InternalRel of G2) or x in X7 or x in X8 by XBOOLE_0:def 3;

            per cases by A29, A31, XBOOLE_0:def 3;

              suppose

               A32: x in the InternalRel of G1;

              

               A33: a in the carrier of G2 by A25, ZFMISC_1: 87;

              a in the carrier of G1 by A32, ZFMISC_1: 87;

              then (the carrier of G1 /\ the carrier of G2) is non empty by A33, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose

               A34: x in X7;

              

               A35: a in the carrier of G2 by A25, ZFMISC_1: 87;

              a in the carrier of G1 by A34, ZFMISC_1: 87;

              then (the carrier of G1 /\ the carrier of G2) is non empty by A35, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose

               A36: x in X8;

              

               A37: b in the carrier of G2 by A25, ZFMISC_1: 87;

              b in the carrier of G1 by A36, ZFMISC_1: 87;

              then (the carrier of G1 /\ the carrier of G2) is non empty by A37, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

          end;

          x in [:the carrier of ( sum_of (G1,G2)), the carrier of ( sum_of (G1,G2)):] by A2, A25, XBOOLE_0:def 3;

          then x in ( [:the carrier of ( sum_of (G1,G2)), the carrier of ( sum_of (G1,G2)):] \ the InternalRel of ( sum_of (G1,G2))) by A30, XBOOLE_0:def 5;

          then x in (the InternalRel of ( sum_of (G1,G2)) ` ) by SUBSET_1:def 4;

          then x in ((the InternalRel of ( sum_of (G1,G2)) ` ) \ ( id the carrier of ( sum_of (G1,G2)))) by A27, XBOOLE_0:def 5;

          hence thesis by NECKLACE:def 8;

        end;

      end;

      

       A38: the carrier of ( union_of (( ComplRelStr G1),( ComplRelStr G2))) = (the carrier of ( ComplRelStr G1) \/ the carrier of ( ComplRelStr G2)) by NECKLA_2:def 2

      .= (the carrier of G1 \/ the carrier of ( ComplRelStr G2)) by NECKLACE:def 8

      .= (the carrier of G1 \/ the carrier of G2) by NECKLACE:def 8;

      the carrier of ( ComplRelStr ( sum_of (G1,G2))) = the carrier of ( sum_of (G1,G2)) by NECKLACE:def 8

      .= (the carrier of G1 \/ the carrier of G2) by NECKLA_2:def 3;

      hence thesis by A38, A3, RELAT_1:def 2;

    end;

    theorem :: NECKLA_3:19

    for G be RelStr, H be full SubRelStr of G holds the InternalRel of ( ComplRelStr H) = (the InternalRel of ( ComplRelStr G) |_2 the carrier of ( ComplRelStr H))

    proof

      let G be RelStr, H be full SubRelStr of G;

      set IH = the InternalRel of H, ICmpH = the InternalRel of ( ComplRelStr H), cH = the carrier of H, IG = the InternalRel of G, cG = the carrier of G, ICmpG = the InternalRel of ( ComplRelStr G);

      

       A1: ICmpH = ((IH ` ) \ ( id cH)) by NECKLACE:def 8

      .= (( [:cH, cH:] \ IH) \ ( id cH)) by SUBSET_1:def 4;

      

       A2: ICmpG = ((IG ` ) \ ( id cG)) by NECKLACE:def 8

      .= (( [:cG, cG:] \ IG) \ ( id cG)) by SUBSET_1:def 4;

      

       A3: cH c= cG by YELLOW_0:def 13;

      (ICmpG |_2 the carrier of ( ComplRelStr H)) = (ICmpG |_2 cH) by NECKLACE:def 8

      .= ((( [:cG, cG:] \ IG) /\ [:cH, cH:]) \ (( id cG) /\ [:cH, cH:])) by A2, XBOOLE_1: 50

      .= ((( [:cG, cG:] /\ [:cH, cH:]) \ (IG /\ [:cH, cH:])) \ (( id cG) /\ [:cH, cH:])) by XBOOLE_1: 50

      .= ((( [:cG, cG:] /\ [:cH, cH:]) \ (IG /\ [:cH, cH:])) \ (( id cG) | cH)) by Th1

      .= ((( [:cG, cG:] /\ [:cH, cH:]) \ (IG |_2 cH)) \ ( id cH)) by A3, FUNCT_3: 1

      .= ((( [:cG, cG:] /\ [:cH, cH:]) \ IH) \ ( id cH)) by YELLOW_0:def 14

      .= (( [:(cG /\ cH), (cG /\ cH):] \ IH) \ ( id cH)) by ZFMISC_1: 100

      .= (( [:cH, (cG /\ cH):] \ IH) \ ( id cH)) by A3, XBOOLE_1: 28

      .= ICmpH by A1, A3, XBOOLE_1: 28;

      hence thesis;

    end;

    theorem :: NECKLA_3:20

    

     Th20: for G be non empty irreflexive RelStr, x be Element of G, x9 be Element of ( ComplRelStr G) st x = x9 holds ( ComplRelStr ( subrelstr (( [#] G) \ {x}))) = ( subrelstr (( [#] ( ComplRelStr G)) \ {x9}))

    proof

      let G be non empty irreflexive RelStr, x be Element of G, x9 be Element of ( ComplRelStr G);

      assume

       A1: x = x9;

      set R = ( subrelstr (( [#] G) \ {x})), cR = the carrier of R, cG = the carrier of G;

      

       A2: ( [#] ( ComplRelStr G)) = cG by NECKLACE:def 8;

      

       A3: [:(cG \ {x}), (cG \ {x}):] = [:cR, (( [#] G) \ {x}):] by YELLOW_0:def 15

      .= [:cR, cR:] by YELLOW_0:def 15;

      

       A4: cR c= cG by YELLOW_0:def 13;

      

       A5: the InternalRel of ( subrelstr (( [#] ( ComplRelStr G)) \ {x9})) = (the InternalRel of ( ComplRelStr G) |_2 the carrier of ( subrelstr (( [#] ( ComplRelStr G)) \ {x9}))) by YELLOW_0:def 14

      .= (the InternalRel of ( ComplRelStr G) |_2 (cG \ {x})) by A1, A2, YELLOW_0:def 15

      .= (((the InternalRel of G ` ) \ ( id cG)) /\ [:(cG \ {x}), (cG \ {x}):]) by NECKLACE:def 8

      .= (( [:cR, cR:] /\ (the InternalRel of G ` )) \ ( id cG)) by A3, XBOOLE_1: 49

      .= (( [:cR, cR:] /\ ( [:cG, cG:] \ the InternalRel of G)) \ ( id cG)) by SUBSET_1:def 4

      .= ((( [:cR, cR:] /\ [:cG, cG:]) \ the InternalRel of G) \ ( id cG)) by XBOOLE_1: 49

      .= (( [:cR, cR:] \ the InternalRel of G) \ ( id cG)) by A4, XBOOLE_1: 28, ZFMISC_1: 96;

      

       A6: the InternalRel of ( ComplRelStr R) = ((the InternalRel of R ` ) \ ( id cR)) by NECKLACE:def 8

      .= (( [:cR, cR:] \ the InternalRel of R) \ ( id cR)) by SUBSET_1:def 4

      .= (( [:cR, cR:] \ (the InternalRel of G |_2 cR)) \ ( id cR)) by YELLOW_0:def 14

      .= ((( [:cR, cR:] \ the InternalRel of G) \/ ( [:cR, cR:] \ [:cR, cR:])) \ ( id cR)) by XBOOLE_1: 54

      .= ((( [:cR, cR:] \ the InternalRel of G) \/ {} ) \ ( id cR)) by XBOOLE_1: 37

      .= (( [:cR, cR:] \ the InternalRel of G) \ ( id cR));

      

       A7: [:cR, cR:] = ( [:( [#] G), (( [#] G) \ {x}):] \ [: {x}, (( [#] G) \ {x}):]) by A3, ZFMISC_1: 102

      .= (( [:( [#] G), ( [#] G):] \ [:( [#] G), {x}:]) \ [: {x}, (( [#] G) \ {x}):]) by ZFMISC_1: 102

      .= (( [:cG, cG:] \ [:cG, {x}:]) \ ( [: {x}, cG:] \ [: {x}, {x}:])) by ZFMISC_1: 102

      .= ((( [:cG, cG:] \ [:cG, {x}:]) \ [: {x}, cG:]) \/ (( [:cG, cG:] \ [:cG, {x}:]) /\ [: {x}, {x}:])) by XBOOLE_1: 52

      .= (( [:cG, cG:] \ ( [:cG, {x}:] \/ [: {x}, cG:])) \/ (( [:cG, cG:] \ [:cG, {x}:]) /\ [: {x}, {x}:])) by XBOOLE_1: 41;

      

       A8: the InternalRel of ( subrelstr (( [#] ( ComplRelStr G)) \ {x9})) = the InternalRel of ( ComplRelStr R)

      proof

        thus the InternalRel of ( subrelstr (( [#] ( ComplRelStr G)) \ {x9})) c= the InternalRel of ( ComplRelStr R)

        proof

          let a be object;

          assume

           A9: a in the InternalRel of ( subrelstr (( [#] ( ComplRelStr G)) \ {x9}));

          then

           A10: not a in ( id cG) by A5, XBOOLE_0:def 5;

          

           A11: not a in ( id cR)

          proof

            assume

             A12: not thesis;

            then

            consider x2,y2 be object such that

             A13: a = [x2, y2] and

             A14: x2 in cR and y2 in cR by RELSET_1: 2;

            

             A15: x2 in (cG \ {x}) by A14, YELLOW_0:def 15;

            x2 = y2 by A12, A13, RELAT_1:def 10;

            hence contradiction by A10, A13, A15, RELAT_1:def 10;

          end;

          a in ( [:cR, cR:] \ the InternalRel of G) by A5, A9, XBOOLE_0:def 5;

          hence thesis by A6, A11, XBOOLE_0:def 5;

        end;

        let a be object;

        assume

         A16: a in the InternalRel of ( ComplRelStr R);

        then not a in ( id cR) by A6, XBOOLE_0:def 5;

        then not a in ( id (cG \ {x})) by YELLOW_0:def 15;

        then

         A17: not a in (( id cG) \ ( id {x})) by SYSREL: 14;

        per cases by A17, XBOOLE_0:def 5;

          suppose

           A18: not a in ( id cG);

          a in ( [:cR, cR:] \ the InternalRel of G) by A6, A16, XBOOLE_0:def 5;

          hence thesis by A5, A18, XBOOLE_0:def 5;

        end;

          suppose a in ( id {x});

          then

           A19: a in { [x, x]} by SYSREL: 13;

          thus thesis

          proof

            per cases by A7, A6, A16, XBOOLE_0:def 3;

              suppose

               A20: a in ( [:cG, cG:] \ ( [:cG, {x}:] \/ [: {x}, cG:]));

              x in {x} by TARSKI:def 1;

              then

               A21: [x, x] in [: {x}, cG:] by ZFMISC_1: 87;

               not a in ( [:cG, {x}:] \/ [: {x}, cG:]) by A20, XBOOLE_0:def 5;

              then not a in [: {x}, cG:] by XBOOLE_0:def 3;

              hence thesis by A19, A21, TARSKI:def 1;

            end;

              suppose

               A22: a in (( [:cG, cG:] \ [:cG, {x}:]) /\ [: {x}, {x}:]);

              x in {x} by TARSKI:def 1;

              then

               A23: [x, x] in [:cG, {x}:] by ZFMISC_1: 87;

              a in ( [:cG, cG:] \ [:cG, {x}:]) by A22, XBOOLE_0:def 4;

              then not a in [:cG, {x}:] by XBOOLE_0:def 5;

              hence thesis by A19, A23, TARSKI:def 1;

            end;

          end;

        end;

      end;

      the carrier of ( ComplRelStr ( subrelstr (( [#] G) \ {x}))) = the carrier of ( subrelstr (( [#] G) \ {x})) by NECKLACE:def 8

      .= (the carrier of G \ {x}) by YELLOW_0:def 15

      .= (( [#] ( ComplRelStr G)) \ {x9}) by A1, NECKLACE:def 8

      .= the carrier of ( subrelstr (( [#] ( ComplRelStr G)) \ {x9})) by YELLOW_0:def 15;

      hence thesis by A8;

    end;

    begin

    registration

      cluster trivial strict -> N-free for non empty RelStr;

      correctness

      proof

        set Y = ( Necklace 4);

        let R be non empty RelStr;

        assume R is trivial strict;

        then

        consider y be object such that

         A1: the carrier of R = {y} by GROUP_6:def 2;

        assume not R is N-free;

        then R embeds Y by NECKLA_2:def 1;

        then

        consider f be Function of Y, R such that

         A2: f is one-to-one and for x,y be Element of Y holds [x, y] in the InternalRel of Y iff [(f . x), (f . y)] in the InternalRel of R;

        

         A3: ( dom f) = the carrier of Y by FUNCT_2:def 1

        .= { 0 , 1, 2, 3} by NECKLACE: 1, NECKLACE: 20;

        then

         A4: 1 in ( dom f) by ENUMSET1:def 2;

        then (f . 1) in {y} by A1, PARTFUN1: 4;

        then

         A5: (f . 1) = y by TARSKI:def 1;

        

         A6: 0 in ( dom f) by A3, ENUMSET1:def 2;

        then (f . 0 ) in {y} by A1, PARTFUN1: 4;

        then (f . 0 ) = y by TARSKI:def 1;

        hence contradiction by A2, A6, A4, A5, FUNCT_1:def 4;

      end;

    end

    theorem :: NECKLA_3:21

    for R be reflexive antisymmetric RelStr, S be RelStr holds (ex f be Function of R, S st for x,y be Element of R holds [x, y] in the InternalRel of R iff [(f . x), (f . y)] in the InternalRel of S) iff S embeds R

    proof

      let R be reflexive antisymmetric RelStr, S be RelStr;

       A1:

      now

        assume ex f be Function of R, S st for x,y be Element of R holds [x, y] in the InternalRel of R iff [(f . x), (f . y)] in the InternalRel of S;

        then

        consider f be Function of R, S such that

         A2: for x,y be Element of R holds [x, y] in the InternalRel of R iff [(f . x), (f . y)] in the InternalRel of S;

        for x1,x2 be object st x1 in ( dom f) & x2 in ( dom f) & (f . x1) = (f . x2) holds x1 = x2

        proof

          let x1,x2 be object;

          assume that

           A3: x1 in ( dom f) and

           A4: x2 in ( dom f) and

           A5: (f . x1) = (f . x2);

          reconsider x1, x2 as Element of R by A3, A4;

          

           A6: the InternalRel of R is_reflexive_in the carrier of R by ORDERS_2:def 2;

          then [x2, x2] in the InternalRel of R by A3;

          then [(f . x2), (f . x1)] in the InternalRel of S by A2, A5;

          then [x2, x1] in the InternalRel of R by A2;

          then

           A7: x2 <= x1 by ORDERS_2:def 5;

           [x1, x1] in the InternalRel of R by A3, A6;

          then [(f . x1), (f . x2)] in the InternalRel of S by A2, A5;

          then [x1, x2] in the InternalRel of R by A2;

          then x1 <= x2 by ORDERS_2:def 5;

          hence thesis by A7, ORDERS_2: 2;

        end;

        then f is one-to-one by FUNCT_1:def 4;

        hence S embeds R by A2;

      end;

      thus thesis by A1;

    end;

    theorem :: NECKLA_3:22

    

     Th22: for G be non empty RelStr, H be non empty full SubRelStr of G holds G embeds H

    proof

      let G be non empty RelStr;

      let H be non empty full SubRelStr of G;

      reconsider f = ( id the carrier of H) as Function of the carrier of H, the carrier of H;

      

       A1: ( dom f) = the carrier of H;

      

       A2: the carrier of H c= the carrier of G by YELLOW_0:def 13;

      for x be object st x in the carrier of H holds (f . x) in the carrier of G

      proof

        let x be object;

        assume x in the carrier of H;

        then (f . x) in the carrier of H by FUNCT_1: 17;

        hence thesis by A2;

      end;

      then

      reconsider f = ( id the carrier of H) as Function of the carrier of H, the carrier of G by A1, FUNCT_2: 3;

      reconsider f as Function of H, G;

      for x,y be Element of H holds [x, y] in the InternalRel of H iff [(f . x), (f . y)] in the InternalRel of G

      proof

        set IH = the InternalRel of H, IG = the InternalRel of G, cH = the carrier of H;

        let x,y be Element of H;

        thus [x, y] in IH implies [(f . x), (f . y)] in IG

        proof

          assume [x, y] in IH;

          then [x, y] in (IG |_2 cH) by YELLOW_0:def 14;

          hence thesis by XBOOLE_0:def 4;

        end;

        assume [(f . x), (f . y)] in IG;

        then [x, y] in (IG |_2 cH) by XBOOLE_0:def 4;

        hence thesis by YELLOW_0:def 14;

      end;

      hence thesis;

    end;

    theorem :: NECKLA_3:23

    

     Th23: for G be non empty RelStr, H be non empty full SubRelStr of G st G is N-free holds H is N-free

    proof

      let G be non empty RelStr, H be non empty full SubRelStr of G;

      assume

       A1: G is N-free;

      

       A2: G embeds H by Th22;

      assume not thesis;

      then H embeds ( Necklace 4) by NECKLA_2:def 1;

      then G embeds ( Necklace 4) by A2, NECKLACE: 12;

      hence contradiction by A1, NECKLA_2:def 1;

    end;

    theorem :: NECKLA_3:24

    

     Th24: for G be non empty irreflexive RelStr holds G embeds ( Necklace 4) iff ( ComplRelStr G) embeds ( Necklace 4)

    proof

      let G be non empty irreflexive RelStr;

      set N4 = ( Necklace 4), CmpN4 = ( ComplRelStr ( Necklace 4)), CmpG = ( ComplRelStr G);

      

       A1: the carrier of CmpG = the carrier of G by NECKLACE:def 8;

      

       A2: the carrier of ( Necklace 4) = { 0 , 1, 2, 3} by NECKLACE: 1, NECKLACE: 20;

      then

       A3: 0 in the carrier of N4 by ENUMSET1:def 2;

      

       A4: the carrier of CmpN4 = the carrier of N4 by NECKLACE:def 8;

      thus G embeds N4 implies CmpG embeds N4

      proof

        (CmpN4,N4) are_isomorphic by NECKLACE: 29, WAYBEL_1: 6;

        then

        consider g be Function of CmpN4, N4 such that

         A5: g is isomorphic by WAYBEL_1:def 8;

        assume G embeds ( Necklace 4);

        then

        consider f be Function of N4, G such that

         A6: f is one-to-one and

         A7: for x,y be Element of N4 holds [x, y] in the InternalRel of N4 iff [(f . x), (f . y)] in the InternalRel of G;

        reconsider h = (f * g) as Function of CmpN4, G;

        

         A8: g is one-to-one monotone by A5, WAYBEL_0:def 38;

        

         A9: for x,y be Element of CmpN4 holds [x, y] in the InternalRel of CmpN4 iff [(h . x), (h . y)] in the InternalRel of G

        proof

          let x,y be Element of CmpN4;

          thus [x, y] in the InternalRel of CmpN4 implies [(h . x), (h . y)] in the InternalRel of G

          proof

            assume [x, y] in the InternalRel of CmpN4;

            then x <= y by ORDERS_2:def 5;

            then (g . x) <= (g . y) by A8, WAYBEL_1:def 2;

            then [(g . x), (g . y)] in the InternalRel of N4 by ORDERS_2:def 5;

            then [(f . (g . x)), (f . (g . y))] in the InternalRel of G by A7;

            then [((f * g) . x), (f . (g . y))] in the InternalRel of G by FUNCT_2: 15;

            hence thesis by FUNCT_2: 15;

          end;

          assume [(h . x), (h . y)] in the InternalRel of G;

          then [(f . (g . x)), (h . y)] in the InternalRel of G by FUNCT_2: 15;

          then [(f . (g . x)), (f . (g . y))] in the InternalRel of G by FUNCT_2: 15;

          then [(g . x), (g . y)] in the InternalRel of N4 by A7;

          then (g . x) <= (g . y) by ORDERS_2:def 5;

          then x <= y by A5, WAYBEL_0: 66;

          hence thesis by ORDERS_2:def 5;

        end;

        

         A10: 0 in the carrier of CmpN4 by A2, A4, ENUMSET1:def 2;

        

         A11: 1 in the carrier of CmpN4 by A2, A4, ENUMSET1:def 2;

        

         A12: ( dom h) = the carrier of CmpN4 by FUNCT_2:def 1;

        

         A13: [(h . 0 ), (h . 1)] in the InternalRel of CmpG

        proof

          assume

           A14: not thesis;

           [(h . 0 ), (h . 1)] in the InternalRel of G

          proof

            (h . 0 ) in the carrier of G & (h . 1) in the carrier of G by A10, A11, FUNCT_2: 5;

            then [(h . 0 ), (h . 1)] in [:the carrier of G, the carrier of G:] by ZFMISC_1: 87;

            then [(h . 0 ), (h . 1)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

            then

             A15: [(h . 0 ), (h . 1)] in (( id the carrier of G) \/ the InternalRel of G) or [(h . 0 ), (h . 1)] in the InternalRel of CmpG by XBOOLE_0:def 3;

            assume not thesis;

            then [(h . 0 ), (h . 1)] in ( id the carrier of G) by A14, A15, XBOOLE_0:def 3;

            then (h . 0 ) = (h . 1) by RELAT_1:def 10;

            hence contradiction by A6, A8, A12, A10, A11, FUNCT_1:def 4;

          end;

          then

           A16: [ 0 , 1] in the InternalRel of CmpN4 by A9, A10, A11;

           [ 0 , 1] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

          then [ 0 , 1] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A16, XBOOLE_0:def 4;

          then the InternalRel of N4 meets the InternalRel of CmpN4;

          hence thesis by Th12;

        end;

        

         A17: 2 in the carrier of CmpN4 by A2, A4, ENUMSET1:def 2;

        

         A18: [(h . 1), (h . 2)] in the InternalRel of CmpG

        proof

          assume

           A19: not thesis;

           [(h . 1), (h . 2)] in the InternalRel of G

          proof

            (h . 1) in the carrier of G & (h . 2) in the carrier of G by A11, A17, FUNCT_2: 5;

            then [(h . 1), (h . 2)] in [:the carrier of G, the carrier of G:] by ZFMISC_1: 87;

            then [(h . 1), (h . 2)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

            then

             A20: [(h . 1), (h . 2)] in (( id the carrier of G) \/ the InternalRel of G) or [(h . 1), (h . 2)] in the InternalRel of CmpG by XBOOLE_0:def 3;

            assume not thesis;

            then [(h . 1), (h . 2)] in ( id the carrier of G) by A19, A20, XBOOLE_0:def 3;

            then (h . 1) = (h . 2) by RELAT_1:def 10;

            hence contradiction by A6, A8, A12, A11, A17, FUNCT_1:def 4;

          end;

          then

           A21: [1, 2] in the InternalRel of CmpN4 by A9, A11, A17;

           [1, 2] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

          then [1, 2] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A21, XBOOLE_0:def 4;

          then the InternalRel of N4 meets the InternalRel of CmpN4;

          hence thesis by Th12;

        end;

        

         A22: 3 in the carrier of CmpN4 by A2, A4, ENUMSET1:def 2;

        

         A23: [(h . 2), (h . 3)] in the InternalRel of CmpG

        proof

          assume

           A24: not thesis;

           [(h . 2), (h . 3)] in the InternalRel of G

          proof

            (h . 2) in the carrier of G & (h . 3) in the carrier of G by A17, A22, FUNCT_2: 5;

            then [(h . 2), (h . 3)] in [:the carrier of G, the carrier of G:] by ZFMISC_1: 87;

            then [(h . 2), (h . 3)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

            then

             A25: [(h . 2), (h . 3)] in (( id the carrier of G) \/ the InternalRel of G) or [(h . 2), (h . 3)] in the InternalRel of CmpG by XBOOLE_0:def 3;

            assume not thesis;

            then [(h . 2), (h . 3)] in ( id the carrier of G) by A24, A25, XBOOLE_0:def 3;

            then (h . 2) = (h . 3) by RELAT_1:def 10;

            hence contradiction by A6, A8, A12, A17, A22, FUNCT_1:def 4;

          end;

          then

           A26: [2, 3] in the InternalRel of CmpN4 by A9, A17, A22;

           [2, 3] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

          then [2, 3] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A26, XBOOLE_0:def 4;

          then the InternalRel of N4 meets the InternalRel of CmpN4;

          hence thesis by Th12;

        end;

         [3, 1] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then

         A27: [(h . 3), (h . 1)] in the InternalRel of G by A9, A11, A22;

         [1, 3] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then

         A28: [(h . 1), (h . 3)] in the InternalRel of G by A9, A11, A22;

         [3, 0 ] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then

         A29: [(h . 3), (h . 0 )] in the InternalRel of G by A9, A10, A22;

         [ 0 , 3] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then

         A30: [(h . 0 ), (h . 3)] in the InternalRel of G by A9, A10, A22;

        

         A31: [(h . 1), (h . 0 )] in the InternalRel of CmpG

        proof

          assume

           A32: not thesis;

           [(h . 1), (h . 0 )] in the InternalRel of G

          proof

            (h . 0 ) in the carrier of G & (h . 1) in the carrier of G by A10, A11, FUNCT_2: 5;

            then [(h . 1), (h . 0 )] in [:the carrier of G, the carrier of G:] by ZFMISC_1: 87;

            then [(h . 1), (h . 0 )] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

            then

             A33: [(h . 1), (h . 0 )] in (( id the carrier of G) \/ the InternalRel of G) or [(h . 1), (h . 0 )] in the InternalRel of CmpG by XBOOLE_0:def 3;

            assume not thesis;

            then [(h . 1), (h . 0 )] in ( id the carrier of G) by A32, A33, XBOOLE_0:def 3;

            then (h . 0 ) = (h . 1) by RELAT_1:def 10;

            hence contradiction by A6, A8, A12, A10, A11, FUNCT_1:def 4;

          end;

          then

           A34: [1, 0 ] in the InternalRel of CmpN4 by A9, A10, A11;

           [1, 0 ] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

          then [1, 0 ] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A34, XBOOLE_0:def 4;

          then the InternalRel of N4 meets the InternalRel of CmpN4;

          hence thesis by Th12;

        end;

        

         A35: [(h . 2), (h . 1)] in the InternalRel of CmpG

        proof

          assume

           A36: not thesis;

           [(h . 2), (h . 1)] in the InternalRel of G

          proof

            (h . 1) in the carrier of G & (h . 2) in the carrier of G by A11, A17, FUNCT_2: 5;

            then [(h . 2), (h . 1)] in [:the carrier of G, the carrier of G:] by ZFMISC_1: 87;

            then [(h . 2), (h . 1)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

            then

             A37: [(h . 2), (h . 1)] in (( id the carrier of G) \/ the InternalRel of G) or [(h . 2), (h . 1)] in the InternalRel of CmpG by XBOOLE_0:def 3;

            assume not thesis;

            then [(h . 2), (h . 1)] in ( id the carrier of G) by A36, A37, XBOOLE_0:def 3;

            then (h . 1) = (h . 2) by RELAT_1:def 10;

            hence contradiction by A6, A8, A12, A11, A17, FUNCT_1:def 4;

          end;

          then

           A38: [2, 1] in the InternalRel of CmpN4 by A9, A11, A17;

           [2, 1] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

          then [2, 1] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A38, XBOOLE_0:def 4;

          then the InternalRel of N4 meets the InternalRel of CmpN4;

          hence thesis by Th12;

        end;

        

         A39: [(h . 3), (h . 2)] in the InternalRel of CmpG

        proof

          assume

           A40: not thesis;

           [(h . 3), (h . 2)] in the InternalRel of G

          proof

            (h . 2) in the carrier of G & (h . 3) in the carrier of G by A17, A22, FUNCT_2: 5;

            then [(h . 3), (h . 2)] in [:the carrier of G, the carrier of G:] by ZFMISC_1: 87;

            then [(h . 3), (h . 2)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

            then

             A41: [(h . 3), (h . 2)] in (( id the carrier of G) \/ the InternalRel of G) or [(h . 3), (h . 2)] in the InternalRel of CmpG by XBOOLE_0:def 3;

            assume not thesis;

            then [(h . 3), (h . 2)] in ( id the carrier of G) by A40, A41, XBOOLE_0:def 3;

            then (h . 2) = (h . 3) by RELAT_1:def 10;

            hence contradiction by A6, A8, A12, A17, A22, FUNCT_1:def 4;

          end;

          then

           A42: [3, 2] in the InternalRel of CmpN4 by A9, A17, A22;

           [3, 2] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

          then [3, 2] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A42, XBOOLE_0:def 4;

          then the InternalRel of N4 meets the InternalRel of CmpN4;

          hence thesis by Th12;

        end;

         [2, 0 ] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then

         A43: [(h . 2), (h . 0 )] in the InternalRel of G by A9, A10, A17;

         [ 0 , 2] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then

         A44: [(h . 0 ), (h . 2)] in the InternalRel of G by A9, A10, A17;

        for x,y be Element of N4 holds [x, y] in the InternalRel of N4 iff [(h . x), (h . y)] in the InternalRel of CmpG

        proof

          let x,y be Element of N4;

          thus [x, y] in the InternalRel of N4 implies [(h . x), (h . y)] in the InternalRel of CmpG

          proof

            assume

             A45: [x, y] in the InternalRel of N4;

            per cases by A45, ENUMSET1:def 4, NECKLA_2: 2;

              suppose

               A46: [x, y] = [ 0 , 1];

              then x = 0 by XTUPLE_0: 1;

              hence thesis by A13, A46, XTUPLE_0: 1;

            end;

              suppose

               A47: [x, y] = [1, 0 ];

              then x = 1 by XTUPLE_0: 1;

              hence thesis by A31, A47, XTUPLE_0: 1;

            end;

              suppose

               A48: [x, y] = [1, 2];

              then x = 1 by XTUPLE_0: 1;

              hence thesis by A18, A48, XTUPLE_0: 1;

            end;

              suppose

               A49: [x, y] = [2, 1];

              then x = 2 by XTUPLE_0: 1;

              hence thesis by A35, A49, XTUPLE_0: 1;

            end;

              suppose

               A50: [x, y] = [2, 3];

              then x = 2 by XTUPLE_0: 1;

              hence thesis by A23, A50, XTUPLE_0: 1;

            end;

              suppose

               A51: [x, y] = [3, 2];

              then x = 3 by XTUPLE_0: 1;

              hence thesis by A39, A51, XTUPLE_0: 1;

            end;

          end;

          assume

           A52: [(h . x), (h . y)] in the InternalRel of CmpG;

          per cases by A2, ENUMSET1:def 2;

            suppose

             A53: x = 0 & y = 0 ;

            then (h . 0 ) in the carrier of CmpG by A52, ZFMISC_1: 87;

            hence thesis by A52, A53, NECKLACE:def 5;

          end;

            suppose x = 0 & y = 1;

            hence thesis by ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose x = 0 & y = 2;

            then [(h . 0 ), (h . 2)] in (the InternalRel of G /\ the InternalRel of CmpG) by A44, A52, XBOOLE_0:def 4;

            then the InternalRel of G meets the InternalRel of CmpG;

            hence thesis by Th12;

          end;

            suppose x = 0 & y = 3;

            then [(h . 0 ), (h . 3)] in (the InternalRel of G /\ the InternalRel of CmpG) by A30, A52, XBOOLE_0:def 4;

            then the InternalRel of G meets the InternalRel of CmpG;

            hence thesis by Th12;

          end;

            suppose x = 1 & y = 0 ;

            hence thesis by ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A54: x = 1 & y = 1;

            then (h . 1) in the carrier of CmpG by A52, ZFMISC_1: 87;

            hence thesis by A52, A54, NECKLACE:def 5;

          end;

            suppose x = 1 & y = 2;

            hence thesis by ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose x = 1 & y = 3;

            then [(h . 1), (h . 3)] in (the InternalRel of G /\ the InternalRel of CmpG) by A28, A52, XBOOLE_0:def 4;

            then the InternalRel of G meets the InternalRel of CmpG;

            hence thesis by Th12;

          end;

            suppose x = 2 & y = 0 ;

            then [(h . 2), (h . 0 )] in (the InternalRel of G /\ the InternalRel of CmpG) by A43, A52, XBOOLE_0:def 4;

            then the InternalRel of G meets the InternalRel of CmpG;

            hence thesis by Th12;

          end;

            suppose x = 2 & y = 1;

            hence thesis by ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A55: x = 2 & y = 2;

            then (h . 2) in the carrier of CmpG by A52, ZFMISC_1: 87;

            hence thesis by A52, A55, NECKLACE:def 5;

          end;

            suppose x = 2 & y = 3;

            hence thesis by ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose x = 3 & y = 0 ;

            then [(h . 3), (h . 0 )] in (the InternalRel of G /\ the InternalRel of CmpG) by A29, A52, XBOOLE_0:def 4;

            then the InternalRel of G meets the InternalRel of CmpG;

            hence thesis by Th12;

          end;

            suppose x = 3 & y = 1;

            then [(h . 3), (h . 1)] in (the InternalRel of G /\ the InternalRel of CmpG) by A27, A52, XBOOLE_0:def 4;

            then the InternalRel of G meets the InternalRel of CmpG;

            hence thesis by Th12;

          end;

            suppose x = 3 & y = 2;

            hence thesis by ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A56: x = 3 & y = 3;

            then (h . 3) in the carrier of CmpG by A52, ZFMISC_1: 87;

            hence thesis by A52, A56, NECKLACE:def 5;

          end;

        end;

        hence thesis by A4, A1, A6, A8;

      end;

      assume CmpG embeds N4;

      then

      consider f be Function of N4, CmpG such that

       A57: f is one-to-one and

       A58: for x,y be Element of N4 holds [x, y] in the InternalRel of N4 iff [(f . x), (f . y)] in the InternalRel of CmpG;

      consider g be Function of N4, CmpN4 such that

       A59: g is isomorphic by NECKLACE: 29, WAYBEL_1:def 8;

      

       A60: 2 in the carrier of N4 by A2, ENUMSET1:def 2;

      

       A61: ( dom f) = the carrier of N4 by FUNCT_2:def 1;

      

       A62: [(f . 0 ), (f . 2)] in the InternalRel of G

      proof

        assume

         A63: not thesis;

         [(f . 0 ), (f . 2)] in the InternalRel of CmpG

        proof

          (f . 0 ) in the carrier of CmpG & (f . 2) in the carrier of CmpG by A3, A60, FUNCT_2: 5;

          then [(f . 0 ), (f . 2)] in [:the carrier of G, the carrier of G:] by A1, ZFMISC_1: 87;

          then [(f . 0 ), (f . 2)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

          then

           A64: [(f . 0 ), (f . 2)] in (( id the carrier of G) \/ the InternalRel of G) or [(f . 0 ), (f . 2)] in the InternalRel of CmpG by XBOOLE_0:def 3;

          assume not thesis;

          then [(f . 0 ), (f . 2)] in ( id the carrier of G) by A63, A64, XBOOLE_0:def 3;

          then (f . 0 ) = (f . 2) by RELAT_1:def 10;

          hence contradiction by A57, A61, A3, A60, FUNCT_1:def 4;

        end;

        then

         A65: [ 0 , 2] in the InternalRel of N4 by A58, A3, A60;

         [ 0 , 2] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then [ 0 , 2] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A65, XBOOLE_0:def 4;

        then the InternalRel of N4 meets the InternalRel of CmpN4;

        hence thesis by Th12;

      end;

      

       A66: 3 in the carrier of N4 by A2, ENUMSET1:def 2;

      

       A67: [(f . 0 ), (f . 3)] in the InternalRel of G

      proof

        assume

         A68: not [(f . 0 ), (f . 3)] in the InternalRel of G;

         [(f . 0 ), (f . 3)] in the InternalRel of CmpG

        proof

          (f . 0 ) in the carrier of CmpG & (f . 3) in the carrier of CmpG by A3, A66, FUNCT_2: 5;

          then [(f . 0 ), (f . 3)] in [:the carrier of G, the carrier of G:] by A1, ZFMISC_1: 87;

          then [(f . 0 ), (f . 3)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

          then

           A69: [(f . 0 ), (f . 3)] in (( id the carrier of G) \/ the InternalRel of G) or [(f . 0 ), (f . 3)] in the InternalRel of CmpG by XBOOLE_0:def 3;

          assume not thesis;

          then [(f . 0 ), (f . 3)] in ( id the carrier of G) by A68, A69, XBOOLE_0:def 3;

          then (f . 0 ) = (f . 3) by RELAT_1:def 10;

          hence contradiction by A57, A61, A3, A66, FUNCT_1:def 4;

        end;

        then

         A70: [ 0 , 3] in the InternalRel of N4 by A58, A3, A66;

         [ 0 , 3] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then [ 0 , 3] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A70, XBOOLE_0:def 4;

        then the InternalRel of N4 meets the InternalRel of CmpN4;

        hence thesis by Th12;

      end;

      

       A71: 1 in the carrier of N4 by A2, ENUMSET1:def 2;

      

       A72: [(f . 1), (f . 3)] in the InternalRel of G

      proof

        assume

         A73: not [(f . 1), (f . 3)] in the InternalRel of G;

         [(f . 1), (f . 3)] in the InternalRel of CmpG

        proof

          (f . 1) in the carrier of CmpG & (f . 3) in the carrier of CmpG by A71, A66, FUNCT_2: 5;

          then [(f . 1), (f . 3)] in [:the carrier of G, the carrier of G:] by A1, ZFMISC_1: 87;

          then [(f . 1), (f . 3)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

          then

           A74: [(f . 1), (f . 3)] in (( id the carrier of G) \/ the InternalRel of G) or [(f . 1), (f . 3)] in the InternalRel of CmpG by XBOOLE_0:def 3;

          assume not thesis;

          then [(f . 1), (f . 3)] in ( id the carrier of G) by A73, A74, XBOOLE_0:def 3;

          then (f . 1) = (f . 3) by RELAT_1:def 10;

          hence contradiction by A57, A61, A71, A66, FUNCT_1:def 4;

        end;

        then

         A75: [1, 3] in the InternalRel of N4 by A58, A71, A66;

         [1, 3] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then [1, 3] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A75, XBOOLE_0:def 4;

        then the InternalRel of N4 meets the InternalRel of CmpN4;

        hence thesis by Th12;

      end;

       [3, 2] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

      then

       A76: [(f . 3), (f . 2)] in the InternalRel of CmpG by A58, A60, A66;

       [2, 3] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

      then

       A77: [(f . 2), (f . 3)] in the InternalRel of CmpG by A58, A60, A66;

       [1, 2] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

      then

       A78: [(f . 1), (f . 2)] in the InternalRel of CmpG by A58, A71, A60;

       [1, 0 ] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

      then

       A79: [(f . 1), (f . 0 )] in the InternalRel of CmpG by A58, A3, A71;

      

       A80: [(f . 2), (f . 0 )] in the InternalRel of G

      proof

        assume

         A81: not [(f . 2), (f . 0 )] in the InternalRel of G;

         [(f . 2), (f . 0 )] in the InternalRel of CmpG

        proof

          (f . 0 ) in the carrier of CmpG & (f . 2) in the carrier of CmpG by A3, A60, FUNCT_2: 5;

          then [(f . 2), (f . 0 )] in [:the carrier of G, the carrier of G:] by A1, ZFMISC_1: 87;

          then [(f . 2), (f . 0 )] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

          then

           A82: [(f . 2), (f . 0 )] in (( id the carrier of G) \/ the InternalRel of G) or [(f . 2), (f . 0 )] in the InternalRel of CmpG by XBOOLE_0:def 3;

          assume not thesis;

          then [(f . 2), (f . 0 )] in ( id the carrier of G) by A81, A82, XBOOLE_0:def 3;

          then (f . 0 ) = (f . 2) by RELAT_1:def 10;

          hence contradiction by A57, A61, A3, A60, FUNCT_1:def 4;

        end;

        then

         A83: [2, 0 ] in the InternalRel of N4 by A58, A3, A60;

         [2, 0 ] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then [2, 0 ] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A83, XBOOLE_0:def 4;

        then the InternalRel of N4 meets the InternalRel of CmpN4;

        hence thesis by Th12;

      end;

      

       A84: [(f . 3), (f . 0 )] in the InternalRel of G

      proof

        assume

         A85: not [(f . 3), (f . 0 )] in the InternalRel of G;

         [(f . 3), (f . 0 )] in the InternalRel of CmpG

        proof

          (f . 0 ) in the carrier of CmpG & (f . 3) in the carrier of CmpG by A3, A66, FUNCT_2: 5;

          then [(f . 3), (f . 0 )] in [:the carrier of G, the carrier of G:] by A1, ZFMISC_1: 87;

          then [(f . 3), (f . 0 )] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

          then

           A86: [(f . 3), (f . 0 )] in (( id the carrier of G) \/ the InternalRel of G) or [(f . 3), (f . 0 )] in the InternalRel of CmpG by XBOOLE_0:def 3;

          assume not thesis;

          then [(f . 3), (f . 0 )] in ( id the carrier of G) by A85, A86, XBOOLE_0:def 3;

          then (f . 0 ) = (f . 3) by RELAT_1:def 10;

          hence contradiction by A57, A61, A3, A66, FUNCT_1:def 4;

        end;

        then

         A87: [3, 0 ] in the InternalRel of N4 by A58, A3, A66;

         [3, 0 ] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then [3, 0 ] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A87, XBOOLE_0:def 4;

        then the InternalRel of N4 meets the InternalRel of CmpN4;

        hence thesis by Th12;

      end;

      

       A88: [(f . 3), (f . 1)] in the InternalRel of G

      proof

        assume

         A89: not [(f . 3), (f . 1)] in the InternalRel of G;

         [(f . 3), (f . 1)] in the InternalRel of CmpG

        proof

          (f . 1) in the carrier of CmpG & (f . 3) in the carrier of CmpG by A71, A66, FUNCT_2: 5;

          then [(f . 3), (f . 1)] in [:the carrier of G, the carrier of G:] by A1, ZFMISC_1: 87;

          then [(f . 3), (f . 1)] in ((( id the carrier of G) \/ the InternalRel of G) \/ the InternalRel of CmpG) by Th14;

          then

           A90: [(f . 3), (f . 1)] in (( id the carrier of G) \/ the InternalRel of G) or [(f . 3), (f . 1)] in the InternalRel of CmpG by XBOOLE_0:def 3;

          assume not thesis;

          then [(f . 3), (f . 1)] in ( id the carrier of G) by A89, A90, XBOOLE_0:def 3;

          then (f . 1) = (f . 3) by RELAT_1:def 10;

          hence contradiction by A57, A61, A71, A66, FUNCT_1:def 4;

        end;

        then

         A91: [3, 1] in the InternalRel of N4 by A58, A71, A66;

         [3, 1] in the InternalRel of CmpN4 by Th11, ENUMSET1:def 4;

        then [3, 1] in (the InternalRel of N4 /\ the InternalRel of CmpN4) by A91, XBOOLE_0:def 4;

        then the InternalRel of N4 meets the InternalRel of CmpN4;

        hence thesis by Th12;

      end;

       [2, 1] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

      then

       A92: [(f . 2), (f . 1)] in the InternalRel of CmpG by A58, A71, A60;

       [ 0 , 1] in the InternalRel of N4 by ENUMSET1:def 4, NECKLA_2: 2;

      then

       A93: [(f . 0 ), (f . 1)] in the InternalRel of CmpG by A58, A3, A71;

      

       A94: for x,y be Element of CmpN4 holds [x, y] in the InternalRel of CmpN4 iff [(f . x), (f . y)] in the InternalRel of G

      proof

        let x,y be Element of CmpN4;

        

         A95: the carrier of N4 = the carrier of CmpN4 by NECKLACE:def 8;

        thus [x, y] in the InternalRel of CmpN4 implies [(f . x), (f . y)] in the InternalRel of G

        proof

          assume

           A96: [x, y] in the InternalRel of CmpN4;

          per cases by A96, Th11, ENUMSET1:def 4;

            suppose

             A97: [x, y] = [ 0 , 2];

            then x = 0 by XTUPLE_0: 1;

            hence thesis by A62, A97, XTUPLE_0: 1;

          end;

            suppose

             A98: [x, y] = [2, 0 ];

            then x = 2 by XTUPLE_0: 1;

            hence thesis by A80, A98, XTUPLE_0: 1;

          end;

            suppose

             A99: [x, y] = [ 0 , 3];

            then x = 0 by XTUPLE_0: 1;

            hence thesis by A67, A99, XTUPLE_0: 1;

          end;

            suppose

             A100: [x, y] = [3, 0 ];

            then x = 3 by XTUPLE_0: 1;

            hence thesis by A84, A100, XTUPLE_0: 1;

          end;

            suppose

             A101: [x, y] = [1, 3];

            then x = 1 by XTUPLE_0: 1;

            hence thesis by A72, A101, XTUPLE_0: 1;

          end;

            suppose

             A102: [x, y] = [3, 1];

            then x = 3 by XTUPLE_0: 1;

            hence thesis by A88, A102, XTUPLE_0: 1;

          end;

        end;

        assume

         A103: [(f . x), (f . y)] in the InternalRel of G;

        per cases by A2, A95, ENUMSET1:def 2;

          suppose

           A104: x = 0 & y = 0 ;

          then (f . 0 ) in the carrier of G by A103, ZFMISC_1: 87;

          hence thesis by A103, A104, NECKLACE:def 5;

        end;

          suppose x = 0 & y = 1;

          then [(f . 0 ), (f . 1)] in (the InternalRel of G /\ the InternalRel of CmpG) by A93, A103, XBOOLE_0:def 4;

          then the InternalRel of G meets the InternalRel of CmpG;

          hence thesis by Th12;

        end;

          suppose x = 0 & y = 2;

          hence thesis by Th11, ENUMSET1:def 4;

        end;

          suppose x = 0 & y = 3;

          hence thesis by Th11, ENUMSET1:def 4;

        end;

          suppose x = 1 & y = 0 ;

          then [(f . 1), (f . 0 )] in (the InternalRel of G /\ the InternalRel of CmpG) by A79, A103, XBOOLE_0:def 4;

          then the InternalRel of G meets the InternalRel of CmpG;

          hence thesis by Th12;

        end;

          suppose x = 2 & y = 0 ;

          hence thesis by Th11, ENUMSET1:def 4;

        end;

          suppose x = 3 & y = 0 ;

          hence thesis by Th11, ENUMSET1:def 4;

        end;

          suppose

           A105: x = 1 & y = 1;

          then (f . 1) in the carrier of G by A103, ZFMISC_1: 87;

          hence thesis by A103, A105, NECKLACE:def 5;

        end;

          suppose x = 1 & y = 2;

          then [(f . 1), (f . 2)] in (the InternalRel of G /\ the InternalRel of CmpG) by A78, A103, XBOOLE_0:def 4;

          then the InternalRel of G meets the InternalRel of CmpG;

          hence thesis by Th12;

        end;

          suppose x = 1 & y = 3;

          hence thesis by Th11, ENUMSET1:def 4;

        end;

          suppose x = 2 & y = 1;

          then [(f . 2), (f . 1)] in (the InternalRel of G /\ the InternalRel of CmpG) by A92, A103, XBOOLE_0:def 4;

          then the InternalRel of G meets the InternalRel of CmpG;

          hence thesis by Th12;

        end;

          suppose

           A106: x = 2 & y = 2;

          then (f . 2) in the carrier of G by A103, ZFMISC_1: 87;

          hence thesis by A103, A106, NECKLACE:def 5;

        end;

          suppose x = 2 & y = 3;

          then [(f . 2), (f . 3)] in (the InternalRel of G /\ the InternalRel of CmpG) by A77, A103, XBOOLE_0:def 4;

          then the InternalRel of G meets the InternalRel of CmpG;

          hence thesis by Th12;

        end;

          suppose x = 3 & y = 1;

          hence thesis by Th11, ENUMSET1:def 4;

        end;

          suppose x = 3 & y = 2;

          then [(f . 3), (f . 2)] in (the InternalRel of G /\ the InternalRel of CmpG) by A76, A103, XBOOLE_0:def 4;

          then the InternalRel of G meets the InternalRel of CmpG;

          hence thesis by Th12;

        end;

          suppose

           A107: x = 3 & y = 3;

          then (f . 3) in the carrier of G by A103, ZFMISC_1: 87;

          hence thesis by A103, A107, NECKLACE:def 5;

        end;

      end;

      reconsider f as Function of CmpN4, G by A4, NECKLACE:def 8;

      reconsider h = (f * g) as Function of N4, G;

      

       A108: g is one-to-one monotone by A59, WAYBEL_0:def 38;

      for x,y be Element of N4 holds [x, y] in the InternalRel of N4 iff [(h . x), (h . y)] in the InternalRel of G

      proof

        let x,y be Element of N4;

        thus [x, y] in the InternalRel of N4 implies [(h . x), (h . y)] in the InternalRel of G

        proof

          assume [x, y] in the InternalRel of N4;

          then x <= y by ORDERS_2:def 5;

          then (g . x) <= (g . y) by A108, WAYBEL_1:def 2;

          then [(g . x), (g . y)] in the InternalRel of CmpN4 by ORDERS_2:def 5;

          then [(f . (g . x)), (f . (g . y))] in the InternalRel of G by A94;

          then [((f * g) . x), (f . (g . y))] in the InternalRel of G by FUNCT_2: 15;

          hence thesis by FUNCT_2: 15;

        end;

        assume [(h . x), (h . y)] in the InternalRel of G;

        then [(f . (g . x)), (h . y)] in the InternalRel of G by FUNCT_2: 15;

        then [(f . (g . x)), (f . (g . y))] in the InternalRel of G by FUNCT_2: 15;

        then [(g . x), (g . y)] in the InternalRel of CmpN4 by A94;

        then (g . x) <= (g . y) by ORDERS_2:def 5;

        then x <= y by A59, WAYBEL_0: 66;

        hence thesis by ORDERS_2:def 5;

      end;

      hence thesis by A57, A108;

    end;

    theorem :: NECKLA_3:25

    

     Th25: for G be non empty irreflexive RelStr holds G is N-free iff ( ComplRelStr G) is N-free

    proof

      let G be non empty irreflexive RelStr;

      thus G is N-free implies ( ComplRelStr G) is N-free

      proof

        assume

         A1: G is N-free;

        assume not thesis;

        then ( ComplRelStr G) embeds ( Necklace 4) by NECKLA_2:def 1;

        then G embeds ( Necklace 4) by Th24;

        hence contradiction by A1, NECKLA_2:def 1;

      end;

      assume

       A2: ( ComplRelStr G) is N-free;

      assume not thesis;

      then G embeds ( Necklace 4) by NECKLA_2:def 1;

      then ( ComplRelStr G) embeds ( Necklace 4) by Th24;

      hence contradiction by A2, NECKLA_2:def 1;

    end;

    begin

    definition

      let R be RelStr;

      mode path of R is RedSequence of the InternalRel of R;

    end

    definition

      let R be RelStr;

      :: NECKLA_3:def1

      attr R is path-connected means for x,y be set st x in the carrier of R & y in the carrier of R & x <> y holds the InternalRel of R reduces (x,y) or the InternalRel of R reduces (y,x);

    end

    registration

      cluster empty -> path-connected for RelStr;

      correctness ;

    end

    registration

      cluster connected -> path-connected for non empty RelStr;

      correctness

      proof

        let R be non empty RelStr;

        set cR = the carrier of R, IR = the InternalRel of R;

        assume

         A1: R is connected;

        for x,y be set st x in the carrier of R & y in the carrier of R & x <> y holds the InternalRel of R reduces (x,y) or the InternalRel of R reduces (y,x)

        proof

          let x,y be set such that

           A2: x in cR & y in cR and x <> y;

          reconsider x, y as Element of R by A2;

          

           A3: x <= y or y <= x by A1, WAYBEL_0:def 29;

          per cases by A3, ORDERS_2:def 5;

            suppose

             A4: [x, y] in IR;

            

             A5: ( len <*x, y*>) = 2 & ( <*x, y*> . 1) = x by FINSEQ_1: 44;

            

             A6: ( <*x, y*> . 2) = y by FINSEQ_1: 44;

             <*x, y*> is RedSequence of IR by A4, REWRITE1: 7;

            hence thesis by A5, A6, REWRITE1:def 3;

          end;

            suppose

             A7: [y, x] in IR;

            

             A8: ( len <*y, x*>) = 2 & ( <*y, x*> . 1) = y by FINSEQ_1: 44;

            

             A9: ( <*y, x*> . 2) = x by FINSEQ_1: 44;

             <*y, x*> is RedSequence of IR by A7, REWRITE1: 7;

            hence thesis by A8, A9, REWRITE1:def 3;

          end;

        end;

        hence thesis;

      end;

    end

    theorem :: NECKLA_3:26

    

     Th26: for R be non empty transitive reflexive RelStr, x,y be Element of R holds the InternalRel of R reduces (x,y) implies [x, y] in the InternalRel of R

    proof

      let R be non empty transitive reflexive RelStr;

      let x,y be Element of R;

      set cR = the carrier of R, IR = the InternalRel of R;

      assume IR reduces (x,y);

      then

      consider p be RedSequence of IR such that

       A1: (p . 1) = x and

       A2: (p . ( len p)) = y by REWRITE1:def 3;

      reconsider p as FinSequence;

      defpred P[ Nat] means $1 in ( dom p) implies [(p . 1), (p . $1)] in IR;

      

       A3: IR is_transitive_in cR by ORDERS_2:def 3;

      

       A4: for k be non zero Nat st P[k] holds P[(k + 1)]

      proof

        let k be non zero Nat such that

         A5: P[k];

        assume

         A6: (k + 1) in ( dom p);

        then k <= (k + 1) & (k + 1) <= ( len p) by FINSEQ_3: 25, NAT_1: 11;

        then

         A7: ( 0 + 1) <= k & k <= ( len p) by NAT_1: 13;

        then

         A8: (p . 1) in cR by A5, FINSEQ_3: 25, ZFMISC_1: 87;

        k in ( dom p) by A7, FINSEQ_3: 25;

        then

         A9: [(p . k), (p . (k + 1))] in IR by A6, REWRITE1:def 2;

        then (p . k) in cR & (p . (k + 1)) in cR by ZFMISC_1: 87;

        hence thesis by A3, A5, A7, A9, A8, FINSEQ_3: 25;

      end;

      IR is_reflexive_in cR by ORDERS_2:def 2;

      then

       A10: P[1] by A1;

      

       A11: for k be non zero Nat holds P[k] from NAT_1:sch 10( A10, A4);

      

       A12: ( len p) > 0 by REWRITE1:def 2;

      then ( 0 + 1) <= ( len p) by NAT_1: 13;

      then ( len p) in ( dom p) by FINSEQ_3: 25;

      hence thesis by A1, A2, A12, A11;

    end;

    registration

      cluster path-connected -> connected for non empty transitive reflexive RelStr;

      correctness

      proof

        let R be non empty transitive reflexive RelStr;

        set IR = the InternalRel of R;

        assume

         A1: R is path-connected;

        for x,y be Element of R holds x <= y or y <= x

        proof

          let x,y be Element of R;

          per cases ;

            suppose x = y;

            hence thesis;

          end;

            suppose x <> y;

            then IR reduces (x,y) or IR reduces (y,x) by A1;

            then [x, y] in IR or [y, x] in IR by Th26;

            hence thesis by ORDERS_2:def 5;

          end;

        end;

        hence thesis by WAYBEL_0:def 29;

      end;

    end

    theorem :: NECKLA_3:27

    

     Th27: for R be symmetric RelStr, x,y be set holds the InternalRel of R reduces (x,y) implies the InternalRel of R reduces (y,x)

    proof

      let R be symmetric RelStr;

      set IR = the InternalRel of R;

      let x,y be set;

      

       A1: IR = (IR ~ ) by RELAT_2: 13;

      assume IR reduces (x,y);

      then

      consider p be RedSequence of IR such that

       A2: (p . 1) = x and

       A3: (p . ( len p)) = y by REWRITE1:def 3;

      reconsider p as FinSequence;

      

       A4: (( Rev p) . ( len p)) = x by A2, FINSEQ_5: 62;

      IR reduces (y,x)

      proof

        reconsider q = ( Rev p) as RedSequence of IR by A1, REWRITE1: 9;

        (q . 1) = y & (q . ( len q)) = x by A3, A4, FINSEQ_5: 62, FINSEQ_5:def 3;

        hence thesis by REWRITE1:def 3;

      end;

      hence thesis;

    end;

    definition

      let R be symmetric RelStr;

      :: original: path-connected

      redefine

      :: NECKLA_3:def2

      attr R is path-connected means for x,y be set st x in the carrier of R & y in the carrier of R & x <> y holds the InternalRel of R reduces (x,y);

      compatibility

      proof

        set IR = the InternalRel of R, cR = the carrier of R;

        thus R is path-connected implies for x,y be set st x in the carrier of R & y in the carrier of R & x <> y holds the InternalRel of R reduces (x,y)

        proof

          assume

           A1: R is path-connected;

          let x,y be set such that

           A2: x in cR & y in cR & x <> y;

          per cases by A1, A2;

            suppose IR reduces (x,y);

            hence thesis;

          end;

            suppose IR reduces (y,x);

            hence thesis by Th27;

          end;

        end;

        assume for x,y be set st x in the carrier of R & y in the carrier of R & x <> y holds IR reduces (x,y);

        then for x,y be set st x in the carrier of R & y in the carrier of R & x <> y holds the InternalRel of R reduces (x,y) or the InternalRel of R reduces (y,x);

        hence thesis;

      end;

    end

    definition

      let R be RelStr;

      let x be Element of R;

      :: NECKLA_3:def3

      func component x -> Subset of R equals ( Class (( EqCl the InternalRel of R),x));

      coherence ;

    end

    registration

      let R be non empty RelStr;

      let x be Element of R;

      cluster ( component x) -> non empty;

      correctness by EQREL_1: 20;

    end

    theorem :: NECKLA_3:28

    

     Th28: for R be RelStr, x be Element of R, y be set st y in ( component x) holds [x, y] in ( EqCl the InternalRel of R)

    proof

      let R be RelStr;

      let x be Element of R;

      let y be set;

      set IR = the InternalRel of R;

      assume y in ( component x);

      then [y, x] in ( EqCl IR) by EQREL_1: 19;

      hence thesis by EQREL_1: 6;

    end;

    theorem :: NECKLA_3:29

    

     Th29: for R be RelStr, x be Element of R, A be set holds A = ( component x) iff for y be object holds y in A iff [x, y] in ( EqCl the InternalRel of R)

    proof

      let R be RelStr;

      let x be Element of R;

      let A be set;

      set IR = the InternalRel of R;

      

       A1: (for y be object holds y in A iff [x, y] in ( EqCl the InternalRel of R)) implies A = ( component x)

      proof

        assume

         A2: for y be object holds y in A iff [x, y] in ( EqCl the InternalRel of R);

        

         A3: ( component x) c= A

        proof

          let a be object;

          assume a in ( component x);

          then [a, x] in ( EqCl IR) by EQREL_1: 19;

          then [x, a] in ( EqCl IR) by EQREL_1: 6;

          hence thesis by A2;

        end;

        A c= ( component x)

        proof

          let a be object;

          assume a in A;

          then [x, a] in ( EqCl IR) by A2;

          then [a, x] in ( EqCl IR) by EQREL_1: 6;

          hence thesis by EQREL_1: 19;

        end;

        hence thesis by A3;

      end;

      A = ( component x) implies for y be object holds [x, y] in ( EqCl IR) implies y in A

      proof

        assume

         A4: A = ( component x);

        let y be object;

        assume [x, y] in ( EqCl IR);

        then [y, x] in ( EqCl IR) by EQREL_1: 6;

        hence thesis by A4, EQREL_1: 19;

      end;

      hence thesis by A1, Th28;

    end;

    theorem :: NECKLA_3:30

    

     Th30: for R be non empty irreflexive symmetric RelStr holds not R is path-connected implies ex G1,G2 be non empty strict irreflexive symmetric RelStr st the carrier of G1 misses the carrier of G2 & the RelStr of R = ( union_of (G1,G2))

    proof

      let R be non empty irreflexive symmetric RelStr;

      set cR = the carrier of R, IR = the InternalRel of R;

      assume not R is path-connected;

      then

      consider x,y be set such that

       A1: x in cR & y in cR and x <> y and

       A2: not IR reduces (x,y);

      reconsider x, y as Element of R by A1;

      set A1 = ( component x), A2 = (the carrier of R \ A1);

      reconsider A2 as Subset of R;

      set G1 = ( subrelstr A1), G2 = ( subrelstr A2);

      

       A3: the carrier of G2 = A2 by YELLOW_0:def 15;

      cR c= (A1 \/ A2)

      proof

        let a be object;

        assume

         A4: a in cR;

        assume not thesis;

        then ( not a in A1) & not a in A2 by XBOOLE_0:def 3;

        hence contradiction by A4, XBOOLE_0:def 5;

      end;

      then

       A5: cR = (A1 \/ A2);

      

       A6: the carrier of G1 = A1 by YELLOW_0:def 15;

      then

       A7: the carrier of G1 misses the carrier of G2 by A3, XBOOLE_1: 79;

      

       A8: the InternalRel of G1 misses the InternalRel of G2

      proof

        set IG1 = the InternalRel of G1, IG2 = the InternalRel of G2;

        assume not thesis;

        then (IG1 /\ IG2) <> {} ;

        then

        consider a be object such that

         A9: a in (IG1 /\ IG2) by XBOOLE_0:def 1;

        a in IG1 by A9, XBOOLE_0:def 4;

        then

        consider c1,c2 be object such that

         A10: a = [c1, c2] and

         A11: c1 in A1 and c2 in A1 by A6, RELSET_1: 2;

        ex g1,g2 be object st a = [g1, g2] & g1 in A2 & g2 in A2 by A3, A9, RELSET_1: 2;

        then c1 in A2 by A10, XTUPLE_0: 1;

        then c1 in (A1 /\ A2) by A11, XBOOLE_0:def 4;

        hence contradiction by A6, A3, A7;

      end;

      

       A12: the InternalRel of G2 = (IR \ the InternalRel of G1)

      proof

        set IG1 = the InternalRel of G1, IG2 = the InternalRel of G2;

        thus IG2 c= (IR \ IG1)

        proof

          let a be object;

          assume

           A13: a in IG2;

          then

          consider g1,g2 be object such that

           A14: a = [g1, g2] and

           A15: g1 in A2 & g2 in A2 by A3, RELSET_1: 2;

          reconsider g1, g2 as Element of G2 by A15, YELLOW_0:def 15;

          reconsider u1 = g1, u2 = g2 as Element of R by A15;

          

           A16: not a in IG1 by A13, XBOOLE_0:def 4, A8;

          g1 <= g2 by A13, A14, ORDERS_2:def 5;

          then u1 <= u2 by YELLOW_0: 59;

          then a in IR by A14, ORDERS_2:def 5;

          hence thesis by A16, XBOOLE_0:def 5;

        end;

        let a be object;

        assume

         A17: a in (IR \ IG1);

        then

         A18: a in IR by XBOOLE_0:def 5;

        

         A19: not a in IG1 by A17, XBOOLE_0:def 5;

        consider c1,c2 be object such that

         A20: a = [c1, c2] and

         A21: c1 in cR & c2 in cR by A17, RELSET_1: 2;

        reconsider c1, c2 as Element of R by A21;

        

         A22: c1 <= c2 by A18, A20, ORDERS_2:def 5;

        per cases by A5, XBOOLE_0:def 3;

          suppose

           A23: c1 in A1 & c2 in A1;

          then

          reconsider d2 = c2 as Element of G1 by YELLOW_0:def 15;

          reconsider d1 = c1 as Element of G1 by A23, YELLOW_0:def 15;

          d1 <= d2 by A6, A22, YELLOW_0: 60;

          hence thesis by A19, A20, ORDERS_2:def 5;

        end;

          suppose

           A24: c1 in A1 & c2 in A2;

          

           A25: [:A1, A2:] misses IR

          proof

            assume not thesis;

            then ( [:A1, A2:] /\ IR) <> {} ;

            then

            consider b be object such that

             A26: b in ( [:A1, A2:] /\ IR) by XBOOLE_0:def 1;

            

             A27: b in IR by A26, XBOOLE_0:def 4;

            b in [:A1, A2:] by A26, XBOOLE_0:def 4;

            then

            consider b1,b2 be object such that

             A28: b1 in A1 and

             A29: b2 in A2 and

             A30: b = [b1, b2] by ZFMISC_1:def 2;

            reconsider b2 as Element of R by A29;

            reconsider b1 as Element of R by A28;

            IR c= ( EqCl IR) & [x, b1] in ( EqCl IR) by A28, Th29, MSUALG_5:def 1;

            then [x, b2] in ( EqCl IR) by A27, A30, EQREL_1: 7;

            then b2 in A1 by Th29;

            then b2 in (A1 /\ A2) by A29, XBOOLE_0:def 4;

            hence thesis by A6, A3, A7;

          end;

          a in [:A1, A2:] by A20, A24, ZFMISC_1:def 2;

          then a in ( [:A1, A2:] /\ IR) by A18, XBOOLE_0:def 4;

          hence thesis by A25;

        end;

          suppose

           A31: c1 in A2 & c2 in A1;

          

           A32: [:A2, A1:] misses IR

          proof

            assume not thesis;

            then ( [:A2, A1:] /\ IR) <> {} ;

            then

            consider b be object such that

             A33: b in ( [:A2, A1:] /\ IR) by XBOOLE_0:def 1;

            b in [:A2, A1:] by A33, XBOOLE_0:def 4;

            then

            consider b1,b2 be object such that

             A34: b1 in A2 and

             A35: b2 in A1 and

             A36: b = [b1, b2] by ZFMISC_1:def 2;

            reconsider b1 as Element of R by A34;

            reconsider b2 as Element of R by A35;

            

             A37: [x, b2] in ( EqCl IR) by A35, Th29;

            

             A38: IR c= ( EqCl IR) by MSUALG_5:def 1;

            b in IR by A33, XBOOLE_0:def 4;

            then [b2, b1] in ( EqCl IR) by A36, A38, EQREL_1: 6;

            then [x, b1] in ( EqCl IR) by A37, EQREL_1: 7;

            then b1 in A1 by Th29;

            then b1 in (A1 /\ A2) by A34, XBOOLE_0:def 4;

            hence thesis by A6, A3, A7;

          end;

          a in [:A2, A1:] by A20, A31, ZFMISC_1:def 2;

          then a in ( [:A2, A1:] /\ IR) by A18, XBOOLE_0:def 4;

          hence thesis by A32;

        end;

          suppose

           A39: c1 in A2 & c2 in A2;

          then

          reconsider d2 = c2 as Element of G2 by YELLOW_0:def 15;

          reconsider d1 = c1 as Element of G2 by A39, YELLOW_0:def 15;

          d1 <= d2 by A3, A22, A39, YELLOW_0: 60;

          hence thesis by A20, ORDERS_2:def 5;

        end;

      end;

      IR = (the InternalRel of G1 \/ the InternalRel of G2)

      proof

        set IG1 = the InternalRel of G1, IG2 = the InternalRel of G2;

        thus IR c= (IG1 \/ IG2)

        proof

          let a be object;

          assume

           A40: a in IR;

          assume not thesis;

          then ( not a in IG1) & not a in IG2 by XBOOLE_0:def 3;

          hence contradiction by A12, A40, XBOOLE_0:def 5;

        end;

        let a be object;

        assume

         A41: a in (IG1 \/ IG2);

        per cases by A41, XBOOLE_0:def 3;

          suppose

           A42: a in IG1;

          then

          consider v,w be object such that

           A43: a = [v, w] and

           A44: v in A1 & w in A1 by A6, RELSET_1: 2;

          reconsider v, w as Element of G1 by A44, YELLOW_0:def 15;

          reconsider u1 = v, u2 = w as Element of R by A44;

          v <= w by A42, A43, ORDERS_2:def 5;

          then u1 <= u2 by YELLOW_0: 59;

          hence thesis by A43, ORDERS_2:def 5;

        end;

          suppose

           A45: a in IG2;

          then

          consider v,w be object such that

           A46: a = [v, w] and

           A47: v in A2 & w in A2 by A3, RELSET_1: 2;

          reconsider v, w as Element of G2 by A47, YELLOW_0:def 15;

          reconsider u1 = v, u2 = w as Element of R by A47;

          v <= w by A45, A46, ORDERS_2:def 5;

          then u1 <= u2 by YELLOW_0: 59;

          hence thesis by A46, ORDERS_2:def 5;

        end;

      end;

      then

       A48: IR = the InternalRel of ( union_of (G1,G2)) by NECKLA_2:def 2;

      IR = (IR ~ ) by RELAT_2: 13;

      then not (IR \/ (IR ~ )) reduces (x,y) by A2;

      then not (x,y) are_convertible_wrt IR by REWRITE1:def 4;

      then not [x, y] in ( EqCl IR) by MSUALG_6: 41;

      then not y in A1 by Th29;

      then

       A49: G2 is non empty strict RelStr by A3, XBOOLE_0:def 5;

      cR = the carrier of ( union_of (G1,G2)) by A6, A3, A5, NECKLA_2:def 2;

      hence thesis by A6, A7, A49, A48;

    end;

    theorem :: NECKLA_3:31

    

     Th31: for R be non empty irreflexive symmetric RelStr holds not ( ComplRelStr R) is path-connected implies ex G1,G2 be non empty strict irreflexive symmetric RelStr st the carrier of G1 misses the carrier of G2 & the RelStr of R = ( sum_of (G1,G2))

    proof

      let R be non empty irreflexive symmetric RelStr;

      set cR = the carrier of R, IR = the InternalRel of R, CR = ( ComplRelStr R), ICR = the InternalRel of ( ComplRelStr R), cCR = the carrier of ( ComplRelStr R);

      assume not CR is path-connected;

      then

      consider x,y be set such that

       A1: x in cCR and

       A2: y in cCR and x <> y and

       A3: not ICR reduces (x,y);

      reconsider x, y as Element of CR by A1, A2;

      set A1 = ( component x), A2 = (the carrier of R \ A1);

      reconsider A1 as Subset of R by NECKLACE:def 8;

      ICR = (ICR ~ ) by RELAT_2: 13;

      then not (ICR \/ (ICR ~ )) reduces (x,y) by A3;

      then not (x,y) are_convertible_wrt ICR by REWRITE1:def 4;

      then not [x, y] in ( EqCl ICR) by MSUALG_6: 41;

      then

       A4: not y in A1 by Th29;

      reconsider A2 as Subset of R;

      set G1 = ( subrelstr A1), G2 = ( subrelstr A2);

      

       A5: the carrier of G1 = A1 by YELLOW_0:def 15;

      set IG1 = the InternalRel of G1, IG2 = the InternalRel of G2, G1G2 = [:the carrier of G1, the carrier of G2:], G2G1 = [:the carrier of G2, the carrier of G1:];

      

       A6: cR = (A1 \/ A2)

      proof

        thus cR c= (A1 \/ A2)

        proof

          let a be object;

          assume

           A7: a in cR;

          assume not thesis;

          then ( not a in A1) & not a in A2 by XBOOLE_0:def 3;

          hence contradiction by A7, XBOOLE_0:def 5;

        end;

        let a be object;

        assume

         A8: a in (A1 \/ A2);

        per cases by A8, XBOOLE_0:def 3;

          suppose a in A1;

          hence thesis;

        end;

          suppose a in A2;

          hence thesis;

        end;

      end;

      

       A9: the carrier of G2 = A2 by YELLOW_0:def 15;

      then

       A10: the carrier of G1 misses the carrier of G2 by A5, XBOOLE_1: 79;

      

       A11: the InternalRel of G1 misses the InternalRel of G2

      proof

        assume not thesis;

        then (IG1 /\ IG2) <> {} ;

        then

        consider a be object such that

         A12: a in (IG1 /\ IG2) by XBOOLE_0:def 1;

        a in IG1 by A12, XBOOLE_0:def 4;

        then

        consider c1,c2 be object such that

         A13: a = [c1, c2] and

         A14: c1 in A1 and c2 in A1 by A5, RELSET_1: 2;

        ex g1,g2 be object st a = [g1, g2] & g1 in A2 & g2 in A2 by A9, A12, RELSET_1: 2;

        then c1 in A2 by A13, XTUPLE_0: 1;

        then c1 in (A1 /\ A2) by A14, XBOOLE_0:def 4;

        hence contradiction by A5, A9, A10;

      end;

      

       A15: the InternalRel of G2 = (((IR \ IG1) \ G1G2) \ G2G1)

      proof

        thus IG2 c= (((IR \ IG1) \ G1G2) \ G2G1)

        proof

          let a be object;

          assume

           A16: a in IG2;

          then

          consider g1,g2 be object such that

           A17: a = [g1, g2] and

           A18: g1 in A2 and

           A19: g2 in A2 by A9, RELSET_1: 2;

          reconsider g1, g2 as Element of G2 by A18, A19, YELLOW_0:def 15;

          reconsider u1 = g1, u2 = g2 as Element of R by A18, A19;

          

           A20: not a in IG1 by A16, XBOOLE_0:def 4, A11;

          

           A21: not a in G2G1

          proof

            assume a in G2G1;

            then g2 in A1 by A5, A17, ZFMISC_1: 87;

            then g2 in (A1 /\ A2) by A19, XBOOLE_0:def 4;

            hence thesis by A5, A9, A10;

          end;

          

           A22: not a in G1G2

          proof

            assume a in G1G2;

            then g1 in A1 by A5, A17, ZFMISC_1: 87;

            then g1 in (A1 /\ A2) by A18, XBOOLE_0:def 4;

            hence thesis by A5, A9, A10;

          end;

          g1 <= g2 by A16, A17, ORDERS_2:def 5;

          then u1 <= u2 by YELLOW_0: 59;

          then a in IR by A17, ORDERS_2:def 5;

          then a in (IR \ IG1) by A20, XBOOLE_0:def 5;

          then a in ((IR \ IG1) \ G1G2) by A22, XBOOLE_0:def 5;

          hence thesis by A21, XBOOLE_0:def 5;

        end;

        let a be object;

        assume

         A23: a in (((IR \ IG1) \ G1G2) \ G2G1);

        then

         A24: not a in G2G1 by XBOOLE_0:def 5;

        

         A25: a in ((IR \ IG1) \ G1G2) by A23, XBOOLE_0:def 5;

        then

         A26: a in (IR \ IG1) by XBOOLE_0:def 5;

        then

         A27: not a in IG1 by XBOOLE_0:def 5;

        

         A28: not a in G1G2 by A25, XBOOLE_0:def 5;

        consider c1,c2 be object such that

         A29: a = [c1, c2] and

         A30: c1 in cR & c2 in cR by A23, RELSET_1: 2;

        reconsider c1, c2 as Element of R by A30;

        a in IR by A26, XBOOLE_0:def 5;

        then

         A31: c1 <= c2 by A29, ORDERS_2:def 5;

        per cases by A6, XBOOLE_0:def 3;

          suppose

           A32: c1 in A1 & c2 in A1;

          then

          reconsider d2 = c2 as Element of G1 by YELLOW_0:def 15;

          reconsider d1 = c1 as Element of G1 by A32, YELLOW_0:def 15;

          d1 <= d2 by A5, A31, YELLOW_0: 60;

          hence thesis by A27, A29, ORDERS_2:def 5;

        end;

          suppose c1 in A1 & c2 in A2;

          hence thesis by A5, A9, A28, A29, ZFMISC_1: 87;

        end;

          suppose c1 in A2 & c2 in A1;

          hence thesis by A5, A9, A24, A29, ZFMISC_1: 87;

        end;

          suppose

           A33: c1 in A2 & c2 in A2;

          then

          reconsider d1 = c1, d2 = c2 as Element of G2 by YELLOW_0:def 15;

          d1 <= d2 by A9, A31, A33, YELLOW_0: 60;

          hence thesis by A29, ORDERS_2:def 5;

        end;

      end;

      IR = (((the InternalRel of G1 \/ the InternalRel of G2) \/ [:the carrier of G1, the carrier of G2:]) \/ [:the carrier of G2, the carrier of G1:])

      proof

        set G1G2 = [:the carrier of G1, the carrier of G2:], G2G1 = [:the carrier of G2, the carrier of G1:];

        thus IR c= (((IG1 \/ IG2) \/ G1G2) \/ G2G1)

        proof

          let a be object;

          assume

           A34: a in IR;

          assume

           A35: not thesis;

          then

           A36: not a in ((IG1 \/ IG2) \/ G1G2) by XBOOLE_0:def 3;

          then

           A37: not a in (IG1 \/ IG2) by XBOOLE_0:def 3;

          then not a in IG2 by XBOOLE_0:def 3;

          then not a in ((IR \ IG1) \ G1G2) or a in G2G1 by A15, XBOOLE_0:def 5;

          then

           A38: not a in (IR \ IG1) or a in G1G2 or a in G2G1 by XBOOLE_0:def 5;

           not a in IG1 by A37, XBOOLE_0:def 3;

          hence thesis by A34, A35, A36, A38, XBOOLE_0:def 3, XBOOLE_0:def 5;

        end;

        let a be object;

        assume a in (((IG1 \/ IG2) \/ G1G2) \/ G2G1);

        then a in ((IG1 \/ IG2) \/ G1G2) or a in G2G1 by XBOOLE_0:def 3;

        then

         A39: a in (IG1 \/ IG2) or a in G1G2 or a in G2G1 by XBOOLE_0:def 3;

        per cases by A39, XBOOLE_0:def 3;

          suppose

           A40: a in IG1;

          then

          consider v,w be object such that

           A41: a = [v, w] and

           A42: v in A1 & w in A1 by A5, RELSET_1: 2;

          reconsider v, w as Element of G1 by A42, YELLOW_0:def 15;

          reconsider u1 = v, u2 = w as Element of R by A42;

          v <= w by A40, A41, ORDERS_2:def 5;

          then u1 <= u2 by YELLOW_0: 59;

          hence thesis by A41, ORDERS_2:def 5;

        end;

          suppose

           A43: a in IG2;

          then

          consider v,w be object such that

           A44: a = [v, w] and

           A45: v in A2 & w in A2 by A9, RELSET_1: 2;

          reconsider v, w as Element of G2 by A45, YELLOW_0:def 15;

          reconsider u1 = v, u2 = w as Element of R by A45;

          v <= w by A43, A44, ORDERS_2:def 5;

          then u1 <= u2 by YELLOW_0: 59;

          hence thesis by A44, ORDERS_2:def 5;

        end;

          suppose

           A46: a in G1G2;

          assume

           A47: not thesis;

          consider v,w be object such that

           A48: a = [v, w] by A46, RELAT_1:def 1;

          

           A49: w in A2 by A9, A46, A48, ZFMISC_1: 87;

          

           A50: v in A1 by A5, A46, A48, ZFMISC_1: 87;

          then

          reconsider v, w as Element of CR by A49, NECKLACE:def 8;

          v <> w by A5, A9, A10, A50, A49, XBOOLE_0:def 4;

          then

           A51: not a in ( id cR) by A48, RELAT_1:def 10;

           [v, w] in [:cR, cR:] by A50, A49, ZFMISC_1: 87;

          then a in ( [:cR, cR:] \ IR) by A48, A47, XBOOLE_0:def 5;

          then a in (IR ` ) by SUBSET_1:def 4;

          then a in ((IR ` ) \ ( id cR)) by A51, XBOOLE_0:def 5;

          then [v, w] in ICR by A48, NECKLACE:def 8;

          then (v,w) are_convertible_wrt ICR by REWRITE1: 29;

          then

           A52: [v, w] in ( EqCl ICR) by MSUALG_6: 41;

           [x, v] in ( EqCl ICR) by A50, Th29;

          then [x, w] in ( EqCl ICR) by A52, EQREL_1: 7;

          then w in ( component x) by Th29;

          then w in (A1 /\ A2) by A49, XBOOLE_0:def 4;

          hence thesis by A5, A9, A10;

        end;

          suppose

           A53: a in G2G1;

          assume

           A54: not thesis;

          consider v,w be object such that

           A55: a = [v, w] by A53, RELAT_1:def 1;

          

           A56: w in A1 by A5, A53, A55, ZFMISC_1: 87;

          

           A57: v in A2 by A9, A53, A55, ZFMISC_1: 87;

          then

          reconsider v, w as Element of CR by A56, NECKLACE:def 8;

          v <> w by A5, A9, A10, A57, A56, XBOOLE_0:def 4;

          then

           A58: not a in ( id cR) by A55, RELAT_1:def 10;

           [v, w] in [:cR, cR:] by A57, A56, ZFMISC_1: 87;

          then a in ( [:cR, cR:] \ IR) by A55, A54, XBOOLE_0:def 5;

          then a in (IR ` ) by SUBSET_1:def 4;

          then a in ((IR ` ) \ ( id cR)) by A58, XBOOLE_0:def 5;

          then [v, w] in ICR by A55, NECKLACE:def 8;

          then (v,w) are_convertible_wrt ICR by REWRITE1: 29;

          then [v, w] in ( EqCl ICR) by MSUALG_6: 41;

          then

           A59: [w, v] in ( EqCl ICR) by EQREL_1: 6;

           [x, w] in ( EqCl ICR) by A56, Th29;

          then [x, v] in ( EqCl ICR) by A59, EQREL_1: 7;

          then v in ( component x) by Th29;

          then v in (A1 /\ A2) by A57, XBOOLE_0:def 4;

          hence thesis by A5, A9, A10;

        end;

      end;

      then

       A60: IR = the InternalRel of ( sum_of (G1,G2)) by NECKLA_2:def 3;

      y in cR by A2, NECKLACE:def 8;

      then

       A61: G2 is non empty strict RelStr by A9, A4, XBOOLE_0:def 5;

      cR = the carrier of ( sum_of (G1,G2)) by A5, A9, A6, NECKLA_2:def 3;

      hence thesis by A5, A10, A61, A60;

    end;

    

     Lm1: for X be non empty finite set, A,B be non empty set st X = (A \/ B) & A misses B holds ( card A) in ( Segm ( card X))

    proof

      let X be non empty finite set;

      let A,B be non empty set;

      set n = ( card X);

      assume that

       A1: X = (A \/ B) and

       A2: A misses B;

      ( card B) c= n by A1, CARD_1: 11, XBOOLE_1: 7;

      then

      reconsider B as finite set;

      ( card A) c= n by A1, CARD_1: 11, XBOOLE_1: 7;

      then

      reconsider A as finite set;

      

       A3: ( card B) >= 1 by NAT_1: 14;

      

       A4: n = (( card A) + ( card B)) by A1, A2, CARD_2: 40;

      ( card A) < n

      proof

        assume not thesis;

        then (( card A) + ( card B)) >= (n + 1) by A3, XREAL_1: 7;

        hence thesis by A4, NAT_1: 13;

      end;

      hence thesis by NAT_1: 44;

    end;

    theorem :: NECKLA_3:32

    for G be irreflexive RelStr st G in fin_RelStr_sp holds ( ComplRelStr G) in fin_RelStr_sp

    proof

      defpred P[ Nat] means for G be irreflexive RelStr st ( card the carrier of G) = $1 & G in fin_RelStr_sp holds ( ComplRelStr G) in fin_RelStr_sp ;

      let G be irreflexive RelStr;

      

       A1: for k be Nat st for n be Nat st n < k holds P[n] holds P[k]

      proof

        let k be Nat such that

         A2: for n be Nat st n < k holds P[n];

        let G be irreflexive RelStr;

        assume that

         A3: ( card the carrier of G) = k and

         A4: G in fin_RelStr_sp ;

        per cases by A4, NECKLA_2: 6;

          suppose G is strict1 -element RelStr;

          hence thesis by A4, Th15;

        end;

          suppose ex G1,G2 be strict RelStr st the carrier of G1 misses the carrier of G2 & G1 in fin_RelStr_sp & G2 in fin_RelStr_sp & (G = ( union_of (G1,G2)) or G = ( sum_of (G1,G2)));

          then

          consider G1,G2 be strict RelStr such that

           A5: the carrier of G1 misses the carrier of G2 and

           A6: G1 in fin_RelStr_sp and

           A7: G2 in fin_RelStr_sp and

           A8: G = ( union_of (G1,G2)) or G = ( sum_of (G1,G2));

          

           A9: G2 is non empty finite by A7, NECKLA_2: 4;

          then

          reconsider n2 = ( card the carrier of G2) as Nat;

          

           A10: G1 is non empty finite by A6, NECKLA_2: 4;

          then

          reconsider n1 = ( card the carrier of G1) as Nat;

          thus thesis

          proof

            per cases by A8;

              suppose

               A11: G = ( union_of (G1,G2));

              then

              reconsider G2 as irreflexive RelStr by Th9;

              reconsider G1 as irreflexive RelStr by A11, Th9;

              reconsider cG1 = the carrier of G1 as non empty finite set by A10;

              reconsider cG2 = the carrier of G2 as non empty finite set by A9;

              the carrier of G = (the carrier of G1 \/ the carrier of G2) by A11, NECKLA_2:def 2;

              then

               A12: ( card the carrier of G) = (( card cG1) + ( card cG2)) by A5, CARD_2: 40;

              

               A13: ( card cG1) = n1;

              n2 < k

              proof

                assume not thesis;

                then (k + 0 ) < (n1 + n2) by A13, XREAL_1: 8;

                hence thesis by A3, A12;

              end;

              then

               A14: ( ComplRelStr G2) in fin_RelStr_sp by A2, A7;

              

               A15: the carrier of ( ComplRelStr G1) = the carrier of G1 & the carrier of ( ComplRelStr G2) = the carrier of G2 by NECKLACE:def 8;

              

               A16: ( card cG2) = n2;

              n1 < k

              proof

                assume not thesis;

                then (k + 0 ) < (n2 + n1) by A16, XREAL_1: 8;

                hence thesis by A3, A12;

              end;

              then

               A17: ( ComplRelStr G1) in fin_RelStr_sp by A2, A6;

              ( ComplRelStr G) = ( sum_of (( ComplRelStr G1),( ComplRelStr G2))) by A5, A11, Th17;

              hence thesis by A5, A17, A14, A15, NECKLA_2:def 5;

            end;

              suppose

               A18: G = ( sum_of (G1,G2));

              then

              reconsider G2 as irreflexive RelStr by Th9;

              reconsider G1 as irreflexive RelStr by A18, Th9;

              reconsider cG1 = the carrier of G1 as non empty finite set by A10;

              reconsider cG2 = the carrier of G2 as non empty finite set by A9;

              the carrier of G = (the carrier of G1 \/ the carrier of G2) by A18, NECKLA_2:def 3;

              then

               A19: ( card the carrier of G) = (( card cG1) + ( card cG2)) by A5, CARD_2: 40;

              

               A20: ( card cG1) = n1;

              n2 < k

              proof

                assume not thesis;

                then (k + 0 ) < (n1 + n2) by A20, XREAL_1: 8;

                hence thesis by A3, A19;

              end;

              then

               A21: ( ComplRelStr G2) in fin_RelStr_sp by A2, A7;

              

               A22: the carrier of ( ComplRelStr G1) = the carrier of G1 & the carrier of ( ComplRelStr G2) = the carrier of G2 by NECKLACE:def 8;

              

               A23: ( card cG2) = n2;

              n1 < k

              proof

                assume not thesis;

                then (k + 0 ) < (n2 + n1) by A23, XREAL_1: 8;

                hence thesis by A3, A19;

              end;

              then

               A24: ( ComplRelStr G1) in fin_RelStr_sp by A2, A6;

              ( ComplRelStr G) = ( union_of (( ComplRelStr G1),( ComplRelStr G2))) by A5, A18, Th18;

              hence thesis by A5, A24, A21, A22, NECKLA_2:def 5;

            end;

          end;

        end;

      end;

      

       A25: for k be Nat holds P[k] from NAT_1:sch 4( A1);

      assume

       A26: G in fin_RelStr_sp ;

      then G is finite by NECKLA_2: 4;

      then ( card the carrier of G) is Nat;

      hence thesis by A26, A25;

    end;

    theorem :: NECKLA_3:33

    

     Th33: for R be irreflexive symmetric RelStr st ( card the carrier of R) = 2 & the carrier of R in FinSETS holds the RelStr of R in fin_RelStr_sp

    proof

      let R be irreflexive symmetric RelStr;

      assume that

       A1: ( card the carrier of R) = 2 and

       A2: the carrier of R in FinSETS ;

      consider a,b be object such that

       A3: the carrier of R = {a, b} and

       A4: the InternalRel of R = { [a, b], [b, a]} or the InternalRel of R = {} by A1, Th6;

      set A = {a}, B = {b};

      

       A5: A c= the carrier of R

      proof

        let x be object;

        assume x in A;

        then x = a by TARSKI:def 1;

        hence thesis by A3, TARSKI:def 2;

      end;

      

       A6: B c= the carrier of R

      proof

        let x be object;

        assume x in B;

        then x = b by TARSKI:def 1;

        hence thesis by A3, TARSKI:def 2;

      end;

      then

      reconsider B as Subset of R;

      reconsider A as Subset of R by A5;

      set H1 = ( subrelstr A), H2 = ( subrelstr B);

      reconsider H2 as non empty strict irreflexive symmetric RelStr by YELLOW_0:def 15;

      

       A7: the carrier of H2 = B by YELLOW_0:def 15;

      then the InternalRel of H2 c= [: {b}, {b}:];

      then the InternalRel of H2 c= { [b, b]} by ZFMISC_1: 29;

      then

       A8: the InternalRel of H2 = {} or the InternalRel of H2 = { [b, b]} by ZFMISC_1: 33;

      

       A9: the InternalRel of H2 = {}

      proof

        b in B by TARSKI:def 1;

        then b in the carrier of H2 by YELLOW_0:def 15;

        then

         A10: not [b, b] in the InternalRel of H2 by NECKLACE:def 5;

        assume not thesis;

        hence thesis by A8, A10, TARSKI:def 1;

      end;

      the carrier of H2 c= the carrier of R by A6, YELLOW_0:def 15;

      then the carrier of H2 in FinSETS by A2, CLASSES1: 3, CLASSES2:def 2;

      then

       A11: H2 in fin_RelStr_sp by A7, NECKLA_2:def 5;

      reconsider H1 as non empty strict irreflexive symmetric RelStr by YELLOW_0:def 15;

      

       A12: the carrier of H1 = A by YELLOW_0:def 15;

      then

       A13: the carrier of R = (the carrier of H1 \/ the carrier of H2) by A3, A7, ENUMSET1: 1;

      a <> b

      proof

        assume not thesis;

        then the carrier of R = {a} by A3, ENUMSET1: 29;

        hence thesis by A1, CARD_1: 30;

      end;

      then

       A14: A misses B by ZFMISC_1: 11;

      then

       A15: the carrier of H1 misses the carrier of H2 by A7, YELLOW_0:def 15;

      the InternalRel of H1 c= [: {a}, {a}:] by A12;

      then the InternalRel of H1 c= { [a, a]} by ZFMISC_1: 29;

      then

       A16: the InternalRel of H1 = {} or the InternalRel of H1 = { [a, a]} by ZFMISC_1: 33;

      

       A17: the InternalRel of H1 = {}

      proof

        a in A by TARSKI:def 1;

        then a in the carrier of H1 by YELLOW_0:def 15;

        then

         A18: not [a, a] in the InternalRel of H1 by NECKLACE:def 5;

        assume not thesis;

        hence thesis by A16, A18, TARSKI:def 1;

      end;

      the carrier of H1 c= the carrier of R by A5, YELLOW_0:def 15;

      then the carrier of H1 in FinSETS by A2, CLASSES1: 3, CLASSES2:def 2;

      then

       A19: H1 in fin_RelStr_sp by A12, NECKLA_2:def 5;

      per cases by A4;

        suppose

         A20: the InternalRel of R = { [a, b], [b, a]};

        set S = ( sum_of (H1,H2));

        the InternalRel of S = (((the InternalRel of H1 \/ the InternalRel of H2) \/ [:A, B:]) \/ [:B, A:]) by A12, A7, NECKLA_2:def 3;

        then the InternalRel of S = ( { [a, b]} \/ [: {b}, {a}:]) by A17, A9, ZFMISC_1: 29;

        then the InternalRel of S = ( { [a, b]} \/ { [b, a]}) by ZFMISC_1: 29;

        then

         A21: the InternalRel of S = the InternalRel of R by A20, ENUMSET1: 1;

        the carrier of S = the carrier of R by A13, NECKLA_2:def 3;

        hence thesis by A12, A19, A7, A11, A14, A21, NECKLA_2:def 5;

      end;

        suppose

         A22: the InternalRel of R = {} ;

        set U = ( union_of (H1,H2));

        the InternalRel of U = (the InternalRel of H1 \/ the InternalRel of H2) & the carrier of U = the carrier of R by A13, NECKLA_2:def 2;

        hence thesis by A19, A11, A15, A17, A9, A22, NECKLA_2:def 5;

      end;

    end;

    theorem :: NECKLA_3:34

    for R be RelStr st R in fin_RelStr_sp holds R is symmetric

    proof

      let X be RelStr;

      assume

       A1: X in fin_RelStr_sp ;

      per cases ;

        suppose

         A2: X is trivial;

        thus thesis

        proof

          per cases by A2, ZFMISC_1: 131;

            suppose

             A3: the carrier of X is empty;

            let a,b be object;

            assume that

             A4: a in the carrier of X and b in the carrier of X and [a, b] in the InternalRel of X;

            thus thesis by A3, A4;

          end;

            suppose ex x be object st the carrier of X = {x};

            then

            consider x be object such that

             A5: the carrier of X = {x};

            

             A6: [:the carrier of X, the carrier of X:] = { [x, x]} by A5, ZFMISC_1: 29;

            thus thesis

            proof

              per cases by A6, ZFMISC_1: 33;

                suppose

                 A7: the InternalRel of X = {} ;

                let a,b be object;

                assume that a in the carrier of X and b in the carrier of X and

                 A8: [a, b] in the InternalRel of X;

                thus thesis by A7, A8;

              end;

                suppose

                 A9: the InternalRel of X = { [x, x]};

                let a,b be object;

                assume that a in the carrier of X and b in the carrier of X and

                 A10: [a, b] in the InternalRel of X;

                

                 A11: [a, b] = [x, x] by A9, A10, TARSKI:def 1;

                then a = x by XTUPLE_0: 1;

                hence thesis by A10, A11, XTUPLE_0: 1;

              end;

            end;

          end;

        end;

      end;

        suppose

         A12: not X is trivial;

        defpred P[ Nat] means for X be non empty RelStr st not X is trivial & X in fin_RelStr_sp holds ( card the carrier of X) c= $1 implies X is symmetric;

        

         A13: ex R be strict RelStr st X = R & the carrier of R in FinSETS by A1, NECKLA_2:def 4;

        reconsider X as non empty RelStr by A1, NECKLA_2: 4;

        

         A14: ( card the carrier of X) is Nat by A13;

        

         A15: for k be Nat st P[k] holds P[(k + 1)]

        proof

          let k be Nat such that

           A16: P[k];

          reconsider k1 = k as Element of NAT by ORDINAL1:def 12;

          let Y be non empty RelStr such that

           A17: not Y is trivial and

           A18: Y in fin_RelStr_sp ;

          consider H1,H2 be strict RelStr such that

           A19: the carrier of H1 misses the carrier of H2 and

           A20: H1 in fin_RelStr_sp and

           A21: H2 in fin_RelStr_sp and

           A22: Y = ( union_of (H1,H2)) or Y = ( sum_of (H1,H2)) by A17, A18, NECKLA_2: 6;

          ex R be strict RelStr st Y = R & the carrier of R in FinSETS by A18, NECKLA_2:def 4;

          then

          reconsider cY = the carrier of Y as finite set;

          assume ( card the carrier of Y) c= (k + 1);

          then ( Segm ( card cY)) c= ( Segm ( card (k1 + 1)));

          then ( card cY) <= ( card (k1 + 1)) by NAT_1: 39;

          then

           A23: ( card cY) <= (k + 1);

          set cH1 = the carrier of H1, cH2 = the carrier of H2;

          

           A24: ( card cY) = ( card (cH1 \/ cH2)) by A22, NECKLA_2:def 2, NECKLA_2:def 3;

          ex R2 be strict RelStr st H2 = R2 & the carrier of R2 in FinSETS by A21, NECKLA_2:def 4;

          then

          reconsider cH2 as finite set;

          ex R1 be strict RelStr st H1 = R1 & the carrier of R1 in FinSETS by A20, NECKLA_2:def 4;

          then

          reconsider cH1 as finite set;

          

           A25: ( card cY) = (( card cH1) + ( card cH2)) by A19, A24, CARD_2: 40;

          H1 is non empty by A20, NECKLA_2: 4;

          then

           A26: ( card cH1) >= 1 by NAT_1: 14;

          H2 is non empty by A21, NECKLA_2: 4;

          then

           A27: ( card cH2) >= 1 by NAT_1: 14;

          per cases by A25, A23, A26, A27, NAT_1: 8, XXREAL_0: 1;

            suppose ( card cY) <= k;

            then ( card cY) <= ( card k1);

            then ( Segm ( card cY)) c= ( Segm ( card k)) by NAT_1: 39;

            then ( card the carrier of Y) c= k1;

            hence thesis by A16, A17, A18;

          end;

            suppose

             A28: ( card cY) = (k + 1) & k = 0 ;

            set x = the set;

            ( card cY) = ( card {x}) by A28, CARD_1: 30;

            then (cY, {x}) are_equipotent by CARD_1: 5;

            then ex y be object st cY = {y} by CARD_1: 28;

            hence thesis by A17;

          end;

            suppose

             A29: (( card cH1) + ( card cH2)) = (k + 1) & k > 0 & ( card cH1) = 1 & ( card cH2) = 1;

            then ex x be object st cH1 = {x} by CARD_2: 42;

            then the InternalRel of H1 is_symmetric_in cH1 by Th5;

            then

            reconsider H1 as symmetric RelStr by NECKLACE:def 3;

            ex y be object st cH2 = {y} by A29, CARD_2: 42;

            then the InternalRel of H2 is_symmetric_in cH2 by Th5;

            then

            reconsider H2 as symmetric RelStr by NECKLACE:def 3;

            ( union_of (H1,H2)) is symmetric;

            hence thesis by A22;

          end;

            suppose

             A30: (( card cH1) + ( card cH2)) = (k + 1) & k > 0 & ( card cH1) = 1 & ( card cH2) > 1;

            then ex x be object st cH1 = {x} by CARD_2: 42;

            then the InternalRel of H1 is_symmetric_in cH1 by Th5;

            then

            reconsider H1 as symmetric RelStr by NECKLACE:def 3;

            ( card cH2) is non trivial by A30, NAT_2: 28;

            then ( card cH2) >= 2 by NAT_2: 29;

            then H2 is non empty non trivial by NAT_D: 60;

            then

            reconsider H2 as symmetric RelStr by A16, A21, A30;

            ( union_of (H1,H2)) is symmetric;

            hence thesis by A22;

          end;

            suppose

             A31: (( card cH1) + ( card cH2)) = (k + 1) & k > 0 & ( card cH1) > 1 & ( card cH2) = 1;

            then ex x be object st cH2 = {x} by CARD_2: 42;

            then the InternalRel of H2 is_symmetric_in cH2 by Th5;

            then

            reconsider H2 as symmetric RelStr by NECKLACE:def 3;

            ( card cH1) is non trivial by A31, NAT_2: 28;

            then ( card cH1) >= 2 by NAT_2: 29;

            then H1 is non empty non trivial by NAT_D: 60;

            then

            reconsider H1 as symmetric RelStr by A16, A20, A31;

            ( union_of (H1,H2)) is symmetric;

            hence thesis by A22;

          end;

            suppose

             A32: (( card cH1) + ( card cH2)) = (k + 1) & k > 0 & ( card cH1) > 1 & ( card cH2) > 1;

            then ( card cH2) is non trivial by NAT_2: 28;

            then ( card cH2) >= 2 by NAT_2: 29;

            then

             A33: H2 is non empty non trivial by NAT_D: 60;

            ( card cH2) < (k + 1)

            proof

              assume not thesis;

              then (( card cH1) + ( card cH2)) >= ((k + 1) + 1) by A26, XREAL_1: 7;

              hence thesis by A32, NAT_1: 13;

            end;

            then ( card cH2) <= k by NAT_1: 13;

            then ( card cH2) <= ( card k1);

            then ( Segm ( card cH2)) c= ( Segm ( card k)) by NAT_1: 39;

            then ( card cH2) c= k1;

            then

            reconsider H2 as symmetric RelStr by A16, A21, A33;

            ( card cH1) is non trivial by A32, NAT_2: 28;

            then ( card cH1) >= 2 by NAT_2: 29;

            then

             A34: H1 is non empty non trivial by NAT_D: 60;

            ( card cH1) < (k + 1)

            proof

              assume not thesis;

              then (( card cH1) + ( card cH2)) >= ((k + 1) + 1) by A27, XREAL_1: 7;

              hence thesis by A32, NAT_1: 13;

            end;

            then ( card cH1) <= k by NAT_1: 13;

            then ( card cH1) <= ( card k1);

            then ( Segm ( card cH1)) c= ( Segm ( card k)) by NAT_1: 39;

            then ( card cH1) c= k1;

            then

            reconsider H1 as symmetric RelStr by A16, A20, A34;

            ( union_of (H1,H2)) is symmetric;

            hence thesis by A22;

          end;

        end;

        

         A35: P[ 0 ];

        for k be Nat holds P[k] from NAT_1:sch 2( A35, A15);

        hence thesis by A1, A12, A14;

      end;

    end;

    theorem :: NECKLA_3:35

    

     Th35: for G be RelStr, H1,H2 be non empty RelStr, x be Element of H1, y be Element of H2 st G = ( union_of (H1,H2)) & the carrier of H1 misses the carrier of H2 holds not [x, y] in the InternalRel of G

    proof

      let G be RelStr;

      let H1,H2 be non empty RelStr;

      let x be Element of H1;

      let y be Element of H2;

      assume that

       A1: G = ( union_of (H1,H2)) and

       A2: the carrier of H1 misses the carrier of H2;

      assume not thesis;

      then

       A3: [x, y] in (the InternalRel of H1 \/ the InternalRel of H2) by A1, NECKLA_2:def 2;

      per cases by A3, XBOOLE_0:def 3;

        suppose [x, y] in the InternalRel of H1;

        then y in the carrier of H1 by ZFMISC_1: 87;

        then y in (the carrier of H1 /\ the carrier of H2) by XBOOLE_0:def 4;

        hence thesis by A2;

      end;

        suppose [x, y] in the InternalRel of H2;

        then x in the carrier of H2 by ZFMISC_1: 87;

        then x in (the carrier of H1 /\ the carrier of H2) by XBOOLE_0:def 4;

        hence thesis by A2;

      end;

    end;

    theorem :: NECKLA_3:36

    for G be RelStr, H1,H2 be non empty RelStr, x be Element of H1, y be Element of H2 st G = ( sum_of (H1,H2)) holds not [x, y] in the InternalRel of ( ComplRelStr G)

    proof

      let G be RelStr, H1,H2 be non empty RelStr, x be Element of H1, y be Element of H2;

      set cH1 = the carrier of H1, cH2 = the carrier of H2, IH1 = the InternalRel of H1, IH2 = the InternalRel of H2;

       [x, y] in ( [:cH1, cH2:] \/ [:cH2, cH1:]) by XBOOLE_0:def 3;

      then [x, y] in (IH2 \/ ( [:cH1, cH2:] \/ [:cH2, cH1:])) by XBOOLE_0:def 3;

      then [x, y] in (IH1 \/ (IH2 \/ ( [:cH1, cH2:] \/ [:cH2, cH1:]))) by XBOOLE_0:def 3;

      then [x, y] in (IH1 \/ ((IH2 \/ [:cH1, cH2:]) \/ [:cH2, cH1:])) by XBOOLE_1: 4;

      then

       A1: [x, y] in (((IH1 \/ IH2) \/ [:cH1, cH2:]) \/ [:cH2, cH1:]) by XBOOLE_1: 113;

      assume G = ( sum_of (H1,H2));

      then

       A2: [x, y] in the InternalRel of G by A1, NECKLA_2:def 3;

       not [x, y] in the InternalRel of ( ComplRelStr G)

      proof

        assume not thesis;

        then [x, y] in (the InternalRel of G /\ the InternalRel of ( ComplRelStr G)) by A2, XBOOLE_0:def 4;

        then the InternalRel of G meets the InternalRel of ( ComplRelStr G);

        hence contradiction by Th12;

      end;

      hence thesis;

    end;

    theorem :: NECKLA_3:37

    

     Th37: for G be non empty symmetric RelStr, x be Element of G, R1,R2 be non empty RelStr st the carrier of R1 misses the carrier of R2 & ( subrelstr (( [#] G) \ {x})) = ( union_of (R1,R2)) & G is path-connected holds ex b be Element of R1 st [b, x] in the InternalRel of G

    proof

      let G be non empty symmetric RelStr;

      let x be Element of G;

      let R1,R2 be non empty RelStr;

      assume that

       A1: the carrier of R1 misses the carrier of R2 and

       A2: ( subrelstr (( [#] G) \ {x})) = ( union_of (R1,R2)) and

       A3: G is path-connected;

      set R = ( subrelstr (( [#] G) \ {x})), A = the carrier of R;

      the carrier of R1 c= (the carrier of R1 \/ the carrier of R2) by XBOOLE_1: 7;

      then

       A4: the carrier of R1 c= the carrier of R by A2, NECKLA_2:def 2;

      set a = the Element of R1;

      

       A5: A = (( [#] G) \ {x}) by YELLOW_0:def 15;

      

       A6: x <> a

      proof

        assume not thesis;

        then x in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

        then x in (the carrier of G \ {x}) by A2, A5, NECKLA_2:def 2;

        then not x in {x} by XBOOLE_0:def 5;

        hence thesis by TARSKI:def 1;

      end;

      reconsider A as Subset of G by YELLOW_0:def 15;

      

       A7: the carrier of R = A;

      then the carrier of R1 c= the carrier of G by A4, XBOOLE_1: 1;

      then a in the carrier of G;

      then the InternalRel of G reduces (x,a) by A3, A6;

      then

      consider p be FinSequence such that

       A8: ( len p) > 0 and

       A9: (p . 1) = x and

       A10: (p . ( len p)) = a and

       A11: for i be Nat st i in ( dom p) & (i + 1) in ( dom p) holds [(p . i), (p . (i + 1))] in the InternalRel of G by REWRITE1: 11;

      defpred P[ Nat] means (p . $1) in the carrier of R1 & $1 in ( dom p) & for k be Nat st k > $1 holds k in ( dom p) implies (p . k) in the carrier of R1;

       P[( len p)] by A8, A10, CARD_1: 27, FINSEQ_3: 25, FINSEQ_5: 6;

      then

       A12: ex k be Nat st P[k];

      ex n0 be Nat st P[n0] & for n be Nat st P[n] holds n >= n0 from NAT_1:sch 5( A12);

      then

      consider n0 be Element of NAT such that

       A13: P[n0] and

       A14: for n be Nat st P[n] holds n >= n0;

      n0 <> 0

      proof

        assume not thesis;

        then 0 in ( Seg ( len p)) by A13, FINSEQ_1:def 3;

        hence contradiction by FINSEQ_1: 1;

      end;

      then

      consider k0 be Nat such that

       A15: n0 = (k0 + 1) by NAT_1: 6;

      

       A16: n0 <> 1

      proof

        assume not thesis;

        then not x in {x} by A5, A4, A9, A13, XBOOLE_0:def 5;

        hence contradiction by TARSKI:def 1;

      end;

      

       A17: k0 >= 1

      proof

        assume not thesis;

        then k0 = 0 by NAT_1: 25;

        hence contradiction by A15, A16;

      end;

      n0 in ( Seg ( len p)) by A13, FINSEQ_1:def 3;

      then

       A18: n0 <= ( len p) by FINSEQ_1: 1;

      

       A19: k0 < n0 by A15, NAT_1: 13;

      

       A20: for k be Nat st k > k0 holds k in ( dom p) implies (p . k) in the carrier of R1

      proof

        assume not thesis;

        then

        consider k be Nat such that

         A21: k > k0 and

         A22: k in ( dom p) and

         A23: not (p . k) in the carrier of R1;

        k > n0

        proof

          per cases by XXREAL_0: 1;

            suppose k < n0;

            hence thesis by A15, A21, NAT_1: 13;

          end;

            suppose n0 < k;

            hence thesis;

          end;

            suppose n0 = k;

            hence thesis by A13, A23;

          end;

        end;

        hence contradiction by A13, A22, A23;

      end;

      

       A24: the carrier of G = (the carrier of R \/ {x})

      proof

        thus the carrier of G c= (the carrier of R \/ {x})

        proof

          let a be object;

          assume

           A25: a in the carrier of G;

          per cases ;

            suppose a = x;

            then a in {x} by TARSKI:def 1;

            hence thesis by XBOOLE_0:def 3;

          end;

            suppose a <> x;

            then not a in {x} by TARSKI:def 1;

            then a in A by A5, A25, XBOOLE_0:def 5;

            hence thesis by XBOOLE_0:def 3;

          end;

        end;

        let a be object;

        assume

         A26: a in (the carrier of R \/ {x});

        per cases by A26, XBOOLE_0:def 3;

          suppose a in the carrier of R;

          hence thesis by A5;

        end;

          suppose a in {x};

          hence thesis;

        end;

      end;

      k0 <= n0 by A15, XREAL_1: 29;

      then k0 <= ( len p) by A18, XXREAL_0: 2;

      then

       A27: k0 in ( dom p) by A17, FINSEQ_3: 25;

      then

       A28: [(p . k0), (p . (k0 + 1))] in the InternalRel of G by A11, A13, A15;

      then

       A29: (p . k0) in the carrier of G by ZFMISC_1: 87;

      thus thesis

      proof

        per cases by A29, A24, XBOOLE_0:def 3;

          suppose

           A30: (p . k0) in the carrier of R;

          set u = (p . k0), v = (p . n0);

           [u, v] in [:the carrier of R, the carrier of R:] by A4, A13, A30, ZFMISC_1: 87;

          then

           A31: [u, v] in (the InternalRel of G |_2 the carrier of R) by A15, A28, XBOOLE_0:def 4;

          (p . k0) in (the carrier of R1 \/ the carrier of R2) by A2, A30, NECKLA_2:def 2;

          then (p . k0) in the carrier of R1 or (p . k0) in the carrier of R2 by XBOOLE_0:def 3;

          then

          reconsider u as Element of R2 by A14, A27, A19, A20;

          reconsider v as Element of R1 by A13;

           not [u, v] in the InternalRel of R

          proof

            u in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A32: u in the carrier of R by A2, NECKLA_2:def 2;

            

             A33: v in the carrier of R1 & the InternalRel of R is_symmetric_in the carrier of R by NECKLACE:def 3;

            assume not thesis;

            then [v, u] in the InternalRel of R by A4, A32, A33;

            hence thesis by A1, A2, Th35;

          end;

          hence thesis by A31, YELLOW_0:def 14;

        end;

          suppose

           A34: (p . k0) in {x};

          set b = (p . n0);

          reconsider b as Element of R1 by A13;

          

           A35: b in the carrier of R & the InternalRel of G is_symmetric_in the carrier of G by A4, NECKLACE:def 3;

          (p . k0) = x by A34, TARSKI:def 1;

          then [b, x] in the InternalRel of G by A7, A15, A28, A35;

          hence thesis;

        end;

      end;

    end;

    theorem :: NECKLA_3:38

    

     Th38: for G be non empty symmetric irreflexive RelStr, a,b,c,d be Element of G, Z be Subset of G st Z = {a, b, c, d} & (a,b,c,d) are_mutually_distinct & [a, b] in the InternalRel of G & [b, c] in the InternalRel of G & [c, d] in the InternalRel of G & not [a, c] in the InternalRel of G & not [a, d] in the InternalRel of G & not [b, d] in the InternalRel of G holds ( subrelstr Z) embeds ( Necklace 4)

    proof

      let G be non empty symmetric irreflexive symmetric RelStr;

      let a,b,c,d be Element of G;

      let Z be Subset of G;

      assume that

       A1: Z = {a, b, c, d} and

       A2: (a,b,c,d) are_mutually_distinct and

       A3: [a, b] in the InternalRel of G and

       A4: [b, c] in the InternalRel of G and

       A5: [c, d] in the InternalRel of G and

       A6: not [a, c] in the InternalRel of G and

       A7: not [a, d] in the InternalRel of G and

       A8: not [b, d] in the InternalRel of G;

      set g = (( 0 ,1) --> (a,b)), h = ((2,3) --> (c,d)), f = (g +* h);

      

       A9: ( rng h) = {c, d} by FUNCT_4: 64;

      

       A10: a <> b by A2, ZFMISC_1:def 6;

      

       A11: ( rng ( 0 .--> a)) misses ( rng (1 .--> b))

      proof

        assume ( rng ( 0 .--> a)) meets ( rng (1 .--> b));

        then

        consider x be object such that

         A12: x in ( rng ( 0 .--> a)) and

         A13: x in ( rng (1 .--> b)) by XBOOLE_0: 3;

        ( rng ( 0 .--> a)) = {a} by FUNCOP_1: 8;

        then ( rng (1 .--> b)) = {b} & x = a by A12, FUNCOP_1: 8, TARSKI:def 1;

        hence contradiction by A10, A13, TARSKI:def 1;

      end;

      set H = ( subrelstr Z), N4 = ( Necklace 4), IH = the InternalRel of H, cH = the carrier of H, IG = the InternalRel of G, X = { [a, a], [a, b], [b, a], [b, b], [a, c], [a, d], [b, c], [b, d]}, Y = { [c, a], [c, b], [d, a], [d, b], [c, c], [c, d], [d, c], [d, d]};

      

       A14: the carrier of H is non empty by A1, YELLOW_0:def 15;

      

       A15: h = ((2 .--> c) +* (3 .--> d)) by FUNCT_4:def 4;

      

       A16: c <> d by A2, ZFMISC_1:def 6;

      ( rng (2 .--> c)) misses ( rng (3 .--> d))

      proof

        assume ( rng (2 .--> c)) meets ( rng (3 .--> d));

        then

        consider x be object such that

         A17: x in ( rng (2 .--> c)) and

         A18: x in ( rng (3 .--> d)) by XBOOLE_0: 3;

        ( rng (2 .--> c)) = {c} by FUNCOP_1: 8;

        then ( rng (3 .--> d)) = {d} & x = c by A17, FUNCOP_1: 8, TARSKI:def 1;

        hence contradiction by A16, A18, TARSKI:def 1;

      end;

      then

       A19: h is one-to-one by A15, FUNCT_4: 92;

      

       A20: ( rng g) = {a, b} by FUNCT_4: 64;

      

       A21: ( rng g) misses ( rng h)

      proof

        assume not thesis;

        then

        consider x be object such that

         A22: x in ( rng g) and

         A23: x in ( rng h) by XBOOLE_0: 3;

        

         A24: x = c or x = d by A9, A23, TARSKI:def 2;

        x = a or x = b by A20, A22, TARSKI:def 2;

        hence contradiction by A2, A24, ZFMISC_1:def 6;

      end;

      ( dom f) = (( dom g) \/ ( dom h)) by FUNCT_4:def 1

      .= ( { 0 , 1} \/ ( dom h)) by FUNCT_4: 62

      .= ( { 0 , 1} \/ {2, 3}) by FUNCT_4: 62

      .= { 0 , 1, 2, 3} by ENUMSET1: 5;

      then

       A25: ( dom f) = the carrier of N4 by NECKLACE: 1, NECKLACE: 20;

      

       A26: ( dom g) misses ( dom h)

      proof

        assume not thesis;

        then

        consider x be object such that

         A27: x in ( dom g) and

         A28: x in ( dom h) by XBOOLE_0: 3;

        x = 0 or x = 1 by A27, TARSKI:def 2;

        hence contradiction by A28, TARSKI:def 2;

      end;

      then ( rng f) = (( rng g) \/ ( rng h)) by NECKLACE: 6;

      then ( rng f) = {a, b, c, d} by A20, A9, ENUMSET1: 5;

      then

       A29: ( rng f) = the carrier of H by A1, YELLOW_0:def 15;

      then

      reconsider f as Function of N4, H by A25, FUNCT_2:def 1, RELSET_1: 4;

      g = (( 0 .--> a) +* (1 .--> b)) by FUNCT_4:def 4;

      then

       A30: g is one-to-one by A11, FUNCT_4: 92;

      then

       A31: f is one-to-one by A19, A21, FUNCT_4: 92;

      

       A32: the InternalRel of H = { [a, b], [b, a], [b, c], [c, b], [c, d], [d, c]}

      proof

        thus the InternalRel of H c= { [a, b], [b, a], [b, c], [c, b], [c, d], [d, c]}

        proof

          let x be object;

          

           A33: the carrier of H = Z by YELLOW_0:def 15;

          assume

           A34: x in IH;

          then

           A35: x in (IG |_2 cH) by YELLOW_0:def 14;

          then

           A36: x in IG by XBOOLE_0:def 4;

          x in [:cH, cH:] by A34;

          then

           A37: x in (X \/ Y) by A1, A33, Th3;

          per cases by A37, XBOOLE_0:def 3;

            suppose

             A38: x in X;

            thus thesis

            proof

              per cases by A38, ENUMSET1:def 6;

                suppose

                 A39: x = [a, a];

                 not [a, a] in IG by NECKLACE:def 5;

                hence thesis by A35, A39, XBOOLE_0:def 4;

              end;

                suppose x = [a, b];

                hence thesis by ENUMSET1:def 4;

              end;

                suppose x = [b, a];

                hence thesis by ENUMSET1:def 4;

              end;

                suppose

                 A40: x = [b, b];

                 not [b, b] in IG by NECKLACE:def 5;

                hence thesis by A35, A40, XBOOLE_0:def 4;

              end;

                suppose x = [a, c];

                hence thesis by A6, A35, XBOOLE_0:def 4;

              end;

                suppose x = [a, d];

                hence thesis by A7, A35, XBOOLE_0:def 4;

              end;

                suppose x = [b, c];

                hence thesis by ENUMSET1:def 4;

              end;

                suppose x = [b, d];

                hence thesis by A8, A35, XBOOLE_0:def 4;

              end;

            end;

          end;

            suppose

             A41: x in Y;

            

             A42: IG is_symmetric_in the carrier of G by NECKLACE:def 3;

            thus thesis

            proof

              per cases by A41, ENUMSET1:def 6;

                suppose x = [c, a];

                hence thesis by A6, A36, A42;

              end;

                suppose x = [c, b];

                hence thesis by ENUMSET1:def 4;

              end;

                suppose x = [d, a];

                hence thesis by A7, A36, A42;

              end;

                suppose x = [d, b];

                hence thesis by A8, A36, A42;

              end;

                suppose

                 A43: x = [c, c];

                 not [c, c] in IG by NECKLACE:def 5;

                hence thesis by A35, A43, XBOOLE_0:def 4;

              end;

                suppose x = [c, d];

                hence thesis by ENUMSET1:def 4;

              end;

                suppose x = [d, c];

                hence thesis by ENUMSET1:def 4;

              end;

                suppose

                 A44: x = [d, d];

                 not [d, d] in IG by NECKLACE:def 5;

                hence thesis by A35, A44, XBOOLE_0:def 4;

              end;

            end;

          end;

        end;

        let x be object;

        assume

         A45: x in { [a, b], [b, a], [b, c], [c, b], [c, d], [d, c]};

        per cases by A45, ENUMSET1:def 4;

          suppose

           A46: x = [a, b];

          b in Z by A1, ENUMSET1:def 2;

          then

           A47: b in cH by YELLOW_0:def 15;

          a in Z by A1, ENUMSET1:def 2;

          then a in cH by YELLOW_0:def 15;

          then [a, b] in [:cH, cH:] by A47, ZFMISC_1: 87;

          then x in (IG |_2 cH) by A3, A46, XBOOLE_0:def 4;

          hence thesis by YELLOW_0:def 14;

        end;

          suppose

           A48: x = [b, a];

          IG is_symmetric_in the carrier of G by NECKLACE:def 3;

          then

           A49: [b, a] in IG by A3;

          a in Z by A1, ENUMSET1:def 2;

          then

           A50: a in cH by YELLOW_0:def 15;

          b in Z by A1, ENUMSET1:def 2;

          then b in cH by YELLOW_0:def 15;

          then [b, a] in [:cH, cH:] by A50, ZFMISC_1: 87;

          then x in (IG |_2 cH) by A48, A49, XBOOLE_0:def 4;

          hence thesis by YELLOW_0:def 14;

        end;

          suppose

           A51: x = [b, c];

          c in Z by A1, ENUMSET1:def 2;

          then

           A52: c in cH by YELLOW_0:def 15;

          b in Z by A1, ENUMSET1:def 2;

          then b in cH by YELLOW_0:def 15;

          then [b, c] in [:cH, cH:] by A52, ZFMISC_1: 87;

          then x in (IG |_2 cH) by A4, A51, XBOOLE_0:def 4;

          hence thesis by YELLOW_0:def 14;

        end;

          suppose

           A53: x = [c, b];

          IG is_symmetric_in the carrier of G by NECKLACE:def 3;

          then

           A54: [c, b] in IG by A4;

          c in Z by A1, ENUMSET1:def 2;

          then

           A55: c in cH by YELLOW_0:def 15;

          b in Z by A1, ENUMSET1:def 2;

          then b in cH by YELLOW_0:def 15;

          then [c, b] in [:cH, cH:] by A55, ZFMISC_1: 87;

          then x in (IG |_2 cH) by A53, A54, XBOOLE_0:def 4;

          hence thesis by YELLOW_0:def 14;

        end;

          suppose

           A56: x = [c, d];

          d in Z by A1, ENUMSET1:def 2;

          then

           A57: d in cH by YELLOW_0:def 15;

          c in Z by A1, ENUMSET1:def 2;

          then c in cH by YELLOW_0:def 15;

          then [c, d] in [:cH, cH:] by A57, ZFMISC_1: 87;

          then x in (IG |_2 cH) by A5, A56, XBOOLE_0:def 4;

          hence thesis by YELLOW_0:def 14;

        end;

          suppose

           A58: x = [d, c];

          IG is_symmetric_in the carrier of G by NECKLACE:def 3;

          then

           A59: [d, c] in IG by A5;

          d in Z by A1, ENUMSET1:def 2;

          then

           A60: d in cH by YELLOW_0:def 15;

          c in Z by A1, ENUMSET1:def 2;

          then c in cH by YELLOW_0:def 15;

          then [d, c] in [:cH, cH:] by A60, ZFMISC_1: 87;

          then x in (IG |_2 cH) by A58, A59, XBOOLE_0:def 4;

          hence thesis by YELLOW_0:def 14;

        end;

      end;

      for x,y be Element of N4 holds [x, y] in the InternalRel of N4 iff [(f . x), (f . y)] in the InternalRel of H

      proof

        let x,y be Element of N4;

        thus [x, y] in the InternalRel of N4 implies [(f . x), (f . y)] in the InternalRel of H

        proof

          assume

           A61: [x, y] in the InternalRel of N4;

          per cases by A61, ENUMSET1:def 4, NECKLA_2: 2;

            suppose

             A62: [x, y] = [ 0 , 1];

            then

             A63: y = 1 by XTUPLE_0: 1;

            then y in { 0 , 1} by TARSKI:def 2;

            then y in ( dom g) by FUNCT_4: 62;

            

            then

             A64: (f . y) = (g . 1) by A26, A63, FUNCT_4: 16

            .= b by FUNCT_4: 63;

            

             A65: x = 0 by A62, XTUPLE_0: 1;

            then x in { 0 , 1} by TARSKI:def 2;

            then x in ( dom g) by FUNCT_4: 62;

            

            then (f . x) = (g . 0 ) by A26, A65, FUNCT_4: 16

            .= a by FUNCT_4: 63;

            hence thesis by A32, A64, ENUMSET1:def 4;

          end;

            suppose

             A66: [x, y] = [1, 0 ];

            then

             A67: y = 0 by XTUPLE_0: 1;

            then y in { 0 , 1} by TARSKI:def 2;

            then y in ( dom g) by FUNCT_4: 62;

            

            then

             A68: (f . y) = (g . 0 ) by A26, A67, FUNCT_4: 16

            .= a by FUNCT_4: 63;

            

             A69: x = 1 by A66, XTUPLE_0: 1;

            then x in { 0 , 1} by TARSKI:def 2;

            then x in ( dom g) by FUNCT_4: 62;

            

            then (f . x) = (g . 1) by A26, A69, FUNCT_4: 16

            .= b by FUNCT_4: 63;

            hence thesis by A32, A68, ENUMSET1:def 4;

          end;

            suppose

             A70: [x, y] = [1, 2];

            then

             A71: x = 1 by XTUPLE_0: 1;

            then x in { 0 , 1} by TARSKI:def 2;

            then x in ( dom g) by FUNCT_4: 62;

            

            then

             A72: (f . x) = (g . 1) by A26, A71, FUNCT_4: 16

            .= b by FUNCT_4: 63;

            

             A73: y = 2 by A70, XTUPLE_0: 1;

            then y in {2, 3} by TARSKI:def 2;

            then

             A74: y in ( dom h) by FUNCT_4: 62;

            (g +* h) = (h +* g) by A26, FUNCT_4: 35;

            

            then (f . y) = (h . 2) by A26, A73, A74, FUNCT_4: 16

            .= c by FUNCT_4: 63;

            hence thesis by A32, A72, ENUMSET1:def 4;

          end;

            suppose

             A75: [x, y] = [2, 1];

            then

             A76: y = 1 by XTUPLE_0: 1;

            then y in { 0 , 1} by TARSKI:def 2;

            then y in ( dom g) by FUNCT_4: 62;

            

            then

             A77: (f . y) = (g . 1) by A26, A76, FUNCT_4: 16

            .= b by FUNCT_4: 63;

            

             A78: x = 2 by A75, XTUPLE_0: 1;

            then x in {2, 3} by TARSKI:def 2;

            then

             A79: x in ( dom h) by FUNCT_4: 62;

            (g +* h) = (h +* g) by A26, FUNCT_4: 35;

            

            then (f . x) = (h . 2) by A26, A78, A79, FUNCT_4: 16

            .= c by FUNCT_4: 63;

            hence thesis by A32, A77, ENUMSET1:def 4;

          end;

            suppose

             A80: [x, y] = [2, 3];

            

             A81: (g +* h) = (h +* g) by A26, FUNCT_4: 35;

            

             A82: y = 3 by A80, XTUPLE_0: 1;

            then y in {2, 3} by TARSKI:def 2;

            then y in ( dom h) by FUNCT_4: 62;

            

            then

             A83: (f . y) = (h . 3) by A26, A82, A81, FUNCT_4: 16

            .= d by FUNCT_4: 63;

            

             A84: x = 2 by A80, XTUPLE_0: 1;

            then x in {2, 3} by TARSKI:def 2;

            then x in ( dom h) by FUNCT_4: 62;

            

            then (f . x) = (h . 2) by A26, A84, A81, FUNCT_4: 16

            .= c by FUNCT_4: 63;

            hence thesis by A32, A83, ENUMSET1:def 4;

          end;

            suppose

             A85: [x, y] = [3, 2];

            

             A86: (g +* h) = (h +* g) by A26, FUNCT_4: 35;

            

             A87: y = 2 by A85, XTUPLE_0: 1;

            then y in {3, 2} by TARSKI:def 2;

            then y in ( dom h) by FUNCT_4: 62;

            

            then

             A88: (f . y) = (h . 2) by A26, A87, A86, FUNCT_4: 16

            .= c by FUNCT_4: 63;

            

             A89: x = 3 by A85, XTUPLE_0: 1;

            then x in {3, 2} by TARSKI:def 2;

            then x in ( dom h) by FUNCT_4: 62;

            

            then (f . x) = (h . 3) by A26, A89, A86, FUNCT_4: 16

            .= d by FUNCT_4: 63;

            hence thesis by A32, A88, ENUMSET1:def 4;

          end;

        end;

        thus [(f . x), (f . y)] in the InternalRel of H implies [x, y] in the InternalRel of N4

        proof

          reconsider F = (f " ) as Function of the carrier of H, the carrier of N4 by A29, A31, FUNCT_2: 25;

          

           A90: ( dom g) = { 0 , 1} by FUNCT_4: 62;

          

           A91: ( rng g) = {a, b} by FUNCT_4: 64;

          then

          reconsider g as Function of { 0 , 1}, {a, b} by A90, RELSET_1: 4;

          reconsider G = (g " ) as Function of {a, b}, { 0 , 1} by A20, A30, FUNCT_2: 25;

          

           A92: ( dom h) = {2, 3} by FUNCT_4: 62;

          

           A93: ( rng h) = {c, d} by FUNCT_4: 64;

          then

          reconsider h as Function of {2, 3}, {c, d} by A92, RELSET_1: 4;

          reconsider Hh = (h " ) as Function of {c, d}, {2, 3} by A9, A19, FUNCT_2: 25;

          

           A94: ( dom Hh) = {c, d} by A19, A93, FUNCT_1: 33;

          

           A95: Hh = ((c,d) --> (2,3)) by A16, NECKLACE: 10;

          

           A96: F = (G +* Hh) by A26, A30, A19, A21, NECKLACE: 7;

          

           A97: G = ((a,b) --> ( 0 ,1)) by A10, NECKLACE: 10;

          

           A98: ( dom G) = {a, b} by A30, A91, FUNCT_1: 33;

          then (G +* Hh) = (Hh +* G) by A20, A9, A21, A94, FUNCT_4: 35;

          then

           A99: F = (Hh +* G) by A26, A30, A19, A21, NECKLACE: 7;

          assume

           A100: [(f . x), (f . y)] in the InternalRel of H;

          per cases by A32, A100, ENUMSET1:def 4;

            suppose

             A101: [(f . x), (f . y)] = [a, b];

            then

             A102: (f . x) = a by XTUPLE_0: 1;

            then (f . x) in {a, b} by TARSKI:def 2;

            

            then (F . (f . x)) = (G . a) by A20, A9, A21, A98, A94, A96, A102, FUNCT_4: 16

            .= 0 by A10, A97, FUNCT_4: 63;

            then

             A103: x = 0 by A14, A31, FUNCT_2: 26;

            

             A104: (f . y) = b by A101, XTUPLE_0: 1;

            then (f . y) in ( dom G) by A98, TARSKI:def 2;

            

            then

             A105: (F . (f . y)) = (G . b) by A20, A9, A21, A98, A94, A96, A104, FUNCT_4: 16

            .= 1 by A97, FUNCT_4: 63;

            (F . (f . y)) = y by A14, A31, FUNCT_2: 26;

            hence thesis by A103, A105, ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A106: [(f . x), (f . y)] = [b, a];

            then

             A107: (f . y) = a by XTUPLE_0: 1;

            then (f . y) in {a, b} by TARSKI:def 2;

            

            then (F . (f . y)) = (G . a) by A20, A9, A21, A98, A94, A96, A107, FUNCT_4: 16

            .= 0 by A10, A97, FUNCT_4: 63;

            then

             A108: y = 0 by A14, A31, FUNCT_2: 26;

            

             A109: (f . x) = b by A106, XTUPLE_0: 1;

            then (f . x) in ( dom G) by A98, TARSKI:def 2;

            

            then

             A110: (F . (f . x)) = (G . b) by A20, A9, A21, A98, A94, A96, A109, FUNCT_4: 16

            .= 1 by A97, FUNCT_4: 63;

            (F . (f . x)) = x by A14, A31, FUNCT_2: 26;

            hence thesis by A108, A110, ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A111: [(f . x), (f . y)] = [b, c];

            then

             A112: (f . x) = b by XTUPLE_0: 1;

            then (f . x) in ( dom G) by A98, TARSKI:def 2;

            

            then (F . (f . x)) = (G . b) by A20, A9, A21, A98, A94, A96, A112, FUNCT_4: 16

            .= 1 by A97, FUNCT_4: 63;

            then

             A113: x = 1 by A14, A31, FUNCT_2: 26;

            

             A114: (f . y) = c by A111, XTUPLE_0: 1;

            then (f . y) in ( dom Hh) by A94, TARSKI:def 2;

            

            then

             A115: (F . (f . y)) = (Hh . c) by A20, A9, A21, A98, A94, A99, A114, FUNCT_4: 16

            .= 2 by A16, A95, FUNCT_4: 63;

            (F . (f . y)) = y by A14, A31, FUNCT_2: 26;

            hence thesis by A113, A115, ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A116: [(f . x), (f . y)] = [c, b];

            then

             A117: (f . y) = b by XTUPLE_0: 1;

            then (f . y) in ( dom G) by A98, TARSKI:def 2;

            

            then (F . (f . y)) = (G . b) by A20, A9, A21, A98, A94, A96, A117, FUNCT_4: 16

            .= 1 by A97, FUNCT_4: 63;

            then

             A118: y = 1 by A14, A31, FUNCT_2: 26;

            

             A119: (f . x) = c by A116, XTUPLE_0: 1;

            then (f . x) in ( dom Hh) by A94, TARSKI:def 2;

            

            then

             A120: (F . (f . x)) = (Hh . c) by A20, A9, A21, A98, A94, A99, A119, FUNCT_4: 16

            .= 2 by A16, A95, FUNCT_4: 63;

            (F . (f . x)) = x by A14, A31, FUNCT_2: 26;

            hence thesis by A118, A120, ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A121: [(f . x), (f . y)] = [c, d];

            then

             A122: (f . x) = c by XTUPLE_0: 1;

            then (f . x) in {c, d} by TARSKI:def 2;

            

            then (F . (f . x)) = (Hh . c) by A20, A9, A21, A98, A94, A99, A122, FUNCT_4: 16

            .= 2 by A16, A95, FUNCT_4: 63;

            then

             A123: x = 2 by A14, A31, FUNCT_2: 26;

            

             A124: (f . y) = d by A121, XTUPLE_0: 1;

            then (f . y) in ( dom Hh) by A94, TARSKI:def 2;

            

            then

             A125: (F . (f . y)) = (Hh . d) by A20, A9, A21, A98, A94, A99, A124, FUNCT_4: 16

            .= 3 by A95, FUNCT_4: 63;

            (F . (f . y)) = y by A14, A31, FUNCT_2: 26;

            hence thesis by A123, A125, ENUMSET1:def 4, NECKLA_2: 2;

          end;

            suppose

             A126: [(f . x), (f . y)] = [d, c];

            then

             A127: (f . y) = c by XTUPLE_0: 1;

            then (f . y) in {c, d} by TARSKI:def 2;

            

            then (F . (f . y)) = (Hh . c) by A20, A9, A21, A98, A94, A99, A127, FUNCT_4: 16

            .= 2 by A16, A95, FUNCT_4: 63;

            then

             A128: y = 2 by A14, A31, FUNCT_2: 26;

            

             A129: (f . x) = d by A126, XTUPLE_0: 1;

            then (f . x) in ( dom Hh) by A94, TARSKI:def 2;

            

            then

             A130: (F . (f . x)) = (Hh . d) by A20, A9, A21, A98, A94, A99, A129, FUNCT_4: 16

            .= 3 by A95, FUNCT_4: 63;

            (F . (f . x)) = x by A14, A31, FUNCT_2: 26;

            hence thesis by A128, A130, ENUMSET1:def 4, NECKLA_2: 2;

          end;

        end;

      end;

      hence thesis by A31;

    end;

    theorem :: NECKLA_3:39

    

     Th39: for G be non empty irreflexive symmetric RelStr, x be Element of G, R1,R2 be non empty RelStr st the carrier of R1 misses the carrier of R2 & ( subrelstr (( [#] G) \ {x})) = ( union_of (R1,R2)) & G is non trivial & G is path-connected & ( ComplRelStr G) is path-connected holds G embeds ( Necklace 4)

    proof

      let G be non empty irreflexive symmetric RelStr, x be Element of G, R1,R2 be non empty RelStr;

      assume that

       A1: the carrier of R1 misses the carrier of R2 and

       A2: ( subrelstr (( [#] G) \ {x})) = ( union_of (R1,R2)) and

       A3: G is non trivial and

       A4: G is path-connected and

       A5: ( ComplRelStr G) is path-connected;

      consider a be Element of R1 such that

       A6: [a, x] in the InternalRel of G by A1, A2, A4, Th37;

      set A = (the carrier of G \ {x}), X = {x};

      reconsider A as Subset of G;

      set R = ( subrelstr A);

      reconsider R as non empty irreflexive symmetric RelStr by A3, YELLOW_0:def 15;

      R = ( subrelstr (( [#] G) \ {x})) & R = ( union_of (R2,R1)) by A2, Th8;

      then

      consider b be Element of R2 such that

       A7: [b, x] in the InternalRel of G by A1, A4, Th37;

      reconsider X1 = { y where y be Element of R1 : [y, x] in the InternalRel of G }, Y1 = { y where y be Element of R1 : not [y, x] in the InternalRel of G }, X2 = { y where y be Element of R2 : [y, x] in the InternalRel of G }, Y2 = { y where y be Element of R2 : not [y, x] in the InternalRel of G } as set;

      reconsider X as Subset of G;

      set H = ( subrelstr X);

      

       A8: X1 misses Y1

      proof

        assume not thesis;

        then

        consider a be object such that

         A9: a in X1 & a in Y1 by XBOOLE_0: 3;

        (ex y1 be Element of R1 st y1 = a & [y1, x] in the InternalRel of G) & ex y2 be Element of R1 st y2 = a & not [y2, x] in the InternalRel of G by A9;

        hence contradiction;

      end;

      

       A10: a in X1 by A6;

      

       A11: the carrier of R1 = (X1 \/ Y1)

      proof

        thus the carrier of R1 c= (X1 \/ Y1)

        proof

          let a be object;

          assume

           A12: a in the carrier of R1;

          per cases ;

            suppose [a, x] in the InternalRel of G;

            then a in X1 by A12;

            hence thesis by XBOOLE_0:def 3;

          end;

            suppose not [a, x] in the InternalRel of G;

            then a in Y1 by A12;

            hence thesis by XBOOLE_0:def 3;

          end;

        end;

        let a be object such that

         A13: a in (X1 \/ Y1);

        per cases by A13, XBOOLE_0:def 3;

          suppose a in X1;

          then ex y be Element of R1 st a = y & [y, x] in the InternalRel of G;

          hence thesis;

        end;

          suppose a in Y1;

          then ex y be Element of R1 st a = y & not [y, x] in the InternalRel of G;

          hence thesis;

        end;

      end;

      

       A14: X2 misses Y2

      proof

        assume not thesis;

        then

        consider a be object such that

         A15: a in X2 & a in Y2 by XBOOLE_0: 3;

        (ex y1 be Element of R2 st y1 = a & [y1, x] in the InternalRel of G) & ex y2 be Element of R2 st y2 = a & not [y2, x] in the InternalRel of G by A15;

        hence contradiction;

      end;

      

       A16: the carrier of H misses the carrier of R

      proof

        assume not thesis;

        then (the carrier of H /\ the carrier of R) <> {} ;

        then (X /\ the carrier of R) <> {} by YELLOW_0:def 15;

        then (X /\ A) <> {} by YELLOW_0:def 15;

        then

        consider a be object such that

         A17: a in (X /\ A) by XBOOLE_0:def 1;

        a in X & a in A by A17, XBOOLE_0:def 4;

        hence contradiction by XBOOLE_0:def 5;

      end;

      reconsider H as non empty irreflexive symmetric RelStr by YELLOW_0:def 15;

      

       A18: b in X2 by A7;

      

       A19: the carrier of G = (the carrier of R \/ {x})

      proof

        thus the carrier of G c= (the carrier of R \/ {x})

        proof

          let a be object;

          assume

           A20: a in the carrier of G;

          per cases ;

            suppose a = x;

            then a in {x} by TARSKI:def 1;

            hence thesis by XBOOLE_0:def 3;

          end;

            suppose a <> x;

            then not a in {x} by TARSKI:def 1;

            then a in (the carrier of G \ {x}) by A20, XBOOLE_0:def 5;

            then a in the carrier of R by YELLOW_0:def 15;

            hence thesis by XBOOLE_0:def 3;

          end;

        end;

        let a be object;

        assume

         A21: a in (the carrier of R \/ {x});

        per cases by A21, XBOOLE_0:def 3;

          suppose a in the carrier of R;

          then a in (the carrier of G \ {x}) by YELLOW_0:def 15;

          hence thesis;

        end;

          suppose a in {x};

          hence thesis;

        end;

      end;

      

       A22: the carrier of R2 = (X2 \/ Y2)

      proof

        thus the carrier of R2 c= (X2 \/ Y2)

        proof

          let a be object;

          assume

           A23: a in the carrier of R2;

          per cases ;

            suppose [a, x] in the InternalRel of G;

            then a in X2 by A23;

            hence thesis by XBOOLE_0:def 3;

          end;

            suppose not [a, x] in the InternalRel of G;

            then a in Y2 by A23;

            hence thesis by XBOOLE_0:def 3;

          end;

        end;

        let a be object such that

         A24: a in (X2 \/ Y2);

        per cases by A24, XBOOLE_0:def 3;

          suppose a in X2;

          then ex y be Element of R2 st a = y & [y, x] in the InternalRel of G;

          hence thesis;

        end;

          suppose a in Y2;

          then ex y be Element of R2 st a = y & not [y, x] in the InternalRel of G;

          hence thesis;

        end;

      end;

      

       A25: (Y1 \/ Y2) is non empty

      proof

        assume

         A26: not thesis;

        then

         A27: Y2 is empty;

        

         A28: Y1 is empty by A26;

        

         A29: for a be Element of R holds [a, x] in the InternalRel of G

        proof

          let a be Element of R;

          

           A30: the carrier of R = (the carrier of R1 \/ the carrier of R2) by A2, NECKLA_2:def 2;

          per cases by A30, XBOOLE_0:def 3;

            suppose a in the carrier of R1;

            then ex y be Element of R1 st a = y & [y, x] in the InternalRel of G by A11, A28;

            hence thesis;

          end;

            suppose a in the carrier of R2;

            then ex y be Element of R2 st a = y & [y, x] in the InternalRel of G by A22, A27;

            hence thesis;

          end;

        end;

         not ( ComplRelStr G) is path-connected

        proof

          

           A31: a <> x

          proof

            assume not thesis;

            then x in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A32: x in the carrier of R by A2, NECKLA_2:def 2;

            x in {x} by TARSKI:def 1;

            then x in the carrier of H by YELLOW_0:def 15;

            then x in (the carrier of R /\ the carrier of H) by A32, XBOOLE_0:def 4;

            hence contradiction by A16;

          end;

          a in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

          then

           A33: a in the carrier of R by A2, NECKLA_2:def 2;

          the carrier of R c= the carrier of G by A19, XBOOLE_1: 7;

          then

           A34: a is Element of ( ComplRelStr G) by A33, NECKLACE:def 8;

          

           A35: x is Element of ( ComplRelStr G) by NECKLACE:def 8;

          assume not thesis;

          then the InternalRel of ( ComplRelStr G) reduces (x,a) by A31, A34, A35;

          then

          consider p be FinSequence such that

           A36: ( len p) > 0 and

           A37: (p . 1) = x and

           A38: (p . ( len p)) = a and

           A39: for i be Nat st i in ( dom p) & (i + 1) in ( dom p) holds [(p . i), (p . (i + 1))] in the InternalRel of ( ComplRelStr G) by REWRITE1: 11;

          

           A40: ( 0 + 1) <= ( len p) by A36, NAT_1: 13;

          then ( len p) > 1 by A31, A37, A38, XXREAL_0: 1;

          then (1 + 1) <= ( len p) by NAT_1: 13;

          then

           A41: 2 in ( dom p) by FINSEQ_3: 25;

          1 in ( dom p) by A40, FINSEQ_3: 25;

          then

           A42: [(p . 1), (p . (1 + 1))] in the InternalRel of ( ComplRelStr G) by A39, A41;

          

           A43: (p . 2) <> x

          proof

            

             A44: [x, x] in ( id the carrier of G) by RELAT_1:def 10;

            assume not thesis;

            then [x, x] in (the InternalRel of ( ComplRelStr G) /\ ( id the carrier of G)) by A37, A42, A44, XBOOLE_0:def 4;

            then the InternalRel of ( ComplRelStr G) meets ( id the carrier of G);

            hence contradiction by Th13;

          end;

          (p . 2) in the carrier of ( ComplRelStr G) by A42, ZFMISC_1: 87;

          then

           A45: (p . 2) in the carrier of G by NECKLACE:def 8;

          (p . 2) in the carrier of R

          proof

            assume not thesis;

            then (p . 2) in {x} by A19, A45, XBOOLE_0:def 3;

            hence thesis by A43, TARSKI:def 1;

          end;

          then

           A46: [(p . 2), x] in the InternalRel of G by A29;

          

           A47: the InternalRel of ( ComplRelStr G) is_symmetric_in the carrier of ( ComplRelStr G) by NECKLACE:def 3;

          (p . 1) in the carrier of ( ComplRelStr G) & (p . (1 + 1)) in the carrier of ( ComplRelStr G) by A42, ZFMISC_1: 87;

          then [(p . (1 + 1)), (p . 1)] in the InternalRel of ( ComplRelStr G) by A42, A47;

          then [(p . 2), x] in (the InternalRel of ( ComplRelStr G) /\ the InternalRel of G) by A37, A46, XBOOLE_0:def 4;

          then the InternalRel of ( ComplRelStr G) meets the InternalRel of G;

          hence thesis by Th12;

        end;

        hence thesis by A5;

      end;

      thus thesis

      proof

        per cases by A25;

          suppose

           A48: Y1 is non empty;

          ex b be Element of Y1, c be Element of X1 st [b, c] in the InternalRel of G

          proof

            set b = the Element of Y1;

            a in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A49: a in the carrier of R by A2, NECKLA_2:def 2;

            b in Y1 by A48;

            then ex y be Element of R1 st y = b & not [y, x] in the InternalRel of G;

            then b in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A50: b in the carrier of R by A2, NECKLA_2:def 2;

            

             A51: the carrier of R c= the carrier of G by A19, XBOOLE_1: 7;

            then

            reconsider a as Element of G by A49;

            reconsider b as Element of G by A51, A50;

            a <> b

            proof

              assume

               A52: not thesis;

              a in X1 by A6;

              then a in (X1 /\ Y1) by A48, A52, XBOOLE_0:def 4;

              hence contradiction by A8;

            end;

            then the InternalRel of G reduces (a,b) by A4;

            then

            consider p be FinSequence such that

             A53: ( len p) > 0 and

             A54: (p . 1) = a and

             A55: (p . ( len p)) = b and

             A56: for i be Nat st i in ( dom p) & (i + 1) in ( dom p) holds [(p . i), (p . (i + 1))] in the InternalRel of G by REWRITE1: 11;

            defpred P[ Nat] means (p . $1) in Y1 & $1 in ( dom p) & for k be Nat st k > $1 holds k in ( dom p) implies (p . k) in Y1;

            for k be Nat st k > ( len p) holds k in ( dom p) implies (p . k) in Y1

            proof

              let k be Nat such that

               A57: k > ( len p);

              assume k in ( dom p);

              then k in ( Seg ( len p)) by FINSEQ_1:def 3;

              hence thesis by A57, FINSEQ_1: 1;

            end;

            then P[( len p)] by A48, A53, A55, CARD_1: 27, FINSEQ_5: 6;

            then

             A58: ex k be Nat st P[k];

            ex n0 be Nat st P[n0] & for n be Nat st P[n] holds n >= n0 from NAT_1:sch 5( A58);

            then

            consider n0 be Nat such that

             A59: P[n0] and

             A60: for n be Nat st P[n] holds n >= n0;

            n0 <> 0

            proof

              assume not thesis;

              then 0 in ( Seg ( len p)) by A59, FINSEQ_1:def 3;

              hence contradiction by FINSEQ_1: 1;

            end;

            then

            consider k0 be Nat such that

             A61: n0 = (k0 + 1) by NAT_1: 6;

            

             A62: n0 <> 1

            proof

              assume

               A63: not thesis;

              a in X1 by A6;

              then (X1 /\ Y1) is non empty by A54, A59, A63, XBOOLE_0:def 4;

              hence contradiction by A8;

            end;

            

             A64: k0 >= 1

            proof

              assume not thesis;

              then k0 = 0 by NAT_1: 25;

              hence contradiction by A61, A62;

            end;

            n0 in ( Seg ( len p)) by A59, FINSEQ_1:def 3;

            then k0 <= (k0 + 1) & n0 <= ( len p) by FINSEQ_1: 1, XREAL_1: 29;

            then

             A65: k0 <= ( len p) by A61, XXREAL_0: 2;

            then

             A66: k0 in ( dom p) by A64, FINSEQ_3: 25;

            then

             A67: [(p . k0), (p . (k0 + 1))] in the InternalRel of G by A56, A59, A61;

            then

             A68: the InternalRel of G is_symmetric_in the carrier of G & (p . k0) in the carrier of G by NECKLACE:def 3, ZFMISC_1: 87;

            (p . n0) in the carrier of G by A61, A67, ZFMISC_1: 87;

            then

             A69: [(p . n0), (p . k0)] in the InternalRel of G by A61, A67, A68;

            

             A70: for k be Nat st k > k0 holds k in ( dom p) implies (p . k) in Y1

            proof

              assume not thesis;

              then

              consider k be Nat such that

               A71: k > k0 and

               A72: k in ( dom p) and

               A73: not (p . k) in Y1;

              k > n0

              proof

                per cases by XXREAL_0: 1;

                  suppose k < n0;

                  hence thesis by A61, A71, NAT_1: 13;

                end;

                  suppose n0 < k;

                  hence thesis;

                end;

                  suppose n0 = k;

                  hence thesis by A59, A73;

                end;

              end;

              hence contradiction by A59, A72, A73;

            end;

            k0 < n0 by A61, NAT_1: 13;

            then

             A74: not P[k0] by A60;

            (p . k0) in the carrier of G by A67, ZFMISC_1: 87;

            then (p . k0) in the carrier of R or (p . k0) in {x} by A19, XBOOLE_0:def 3;

            then

             A75: (p . k0) in (the carrier of R1 \/ the carrier of R2) or (p . k0) in {x} by A2, NECKLA_2:def 2;

            thus thesis

            proof

              per cases by A61, A67, A75, XBOOLE_0:def 3, ZFMISC_1: 87;

                suppose

                 A76: (p . k0) in the carrier of R1 & (p . n0) in the carrier of G;

                then

                reconsider m = (p . k0) as Element of X1 by A11, A64, A65, A74, A70, FINSEQ_3: 25, XBOOLE_0:def 3;

                m in (the carrier of R1 \/ the carrier of R2) by A76, XBOOLE_0:def 3;

                then

                 A77: m in the carrier of R by A2, NECKLA_2:def 2;

                reconsider l = (p . n0) as Element of Y1 by A59;

                

                 A78: the carrier of R c= the carrier of G by A19, XBOOLE_1: 7;

                l in the carrier of R1 by A11, A59, XBOOLE_0:def 3;

                then l in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

                then

                 A79: l in the carrier of R by A2, NECKLA_2:def 2;

                 [m, l] in the InternalRel of G & the InternalRel of G is_symmetric_in the carrier of G by A56, A59, A61, A66, NECKLACE:def 3;

                then [l, m] in the InternalRel of G by A79, A77, A78;

                hence thesis;

              end;

                suppose (p . k0) in the carrier of R2 & (p . n0) in the carrier of G;

                then

                reconsider m = (p . k0) as Element of R2;

                reconsider l = (p . n0) as Element of R1 by A11, A59, XBOOLE_0:def 3;

                m in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

                then

                 A80: m in the carrier of R by A2, NECKLA_2:def 2;

                l in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

                then l in the carrier of R by A2, NECKLA_2:def 2;

                then [l, m] in [:the carrier of R, the carrier of R:] by A80, ZFMISC_1: 87;

                then [l, m] in (the InternalRel of G |_2 the carrier of R) by A69, XBOOLE_0:def 4;

                then [l, m] in the InternalRel of R by YELLOW_0:def 14;

                hence thesis by A1, A2, Th35;

              end;

                suppose

                 A81: (p . k0) in {x} & (p . n0) in the carrier of G;

                ex y1 be Element of R1 st (p . n0) = y1 & not [y1, x] in the InternalRel of G by A59;

                hence thesis by A69, A81, TARSKI:def 1;

              end;

            end;

          end;

          then

          consider u be Element of Y1, v be Element of X1 such that

           A82: [u, v] in the InternalRel of G;

          set w = the Element of X2;

          w in X2 by A18;

          then

           A83: ex y be Element of R2 st y = w & [y, x] in the InternalRel of G;

          set Z = {u, v, x, w};

          Z c= the carrier of G

          proof

            w in X2 by A18;

            then ex y2 be Element of R2 st y2 = w & [y2, x] in the InternalRel of G;

            then w in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A84: w in the carrier of R by A2, NECKLA_2:def 2;

            v in X1 by A10;

            then ex y1 be Element of R1 st y1 = v & [y1, x] in the InternalRel of G;

            then v in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A85: v in the carrier of R by A2, NECKLA_2:def 2;

            u in the carrier of R1 by A11, A48, XBOOLE_0:def 3;

            then u in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A86: u in the carrier of R by A2, NECKLA_2:def 2;

            let q be object;

            assume q in Z;

            then

             A87: q = u or q = v or q = x or q = w by ENUMSET1:def 2;

            the carrier of R c= the carrier of G by A19, XBOOLE_1: 7;

            hence thesis by A87, A86, A85, A84;

          end;

          then

          reconsider Z as Subset of G;

          reconsider H = ( subrelstr Z) as non empty full SubRelStr of G by YELLOW_0:def 15;

          

           A88: w in X2 by A18;

          reconsider w as Element of G by A83, ZFMISC_1: 87;

          

           A89: v in X1 by A10;

          

           A90: [x, w] in the InternalRel of G

          proof

            (ex y1 be Element of R2 st w = y1 & [y1, x] in the InternalRel of G) & the InternalRel of G is_symmetric_in the carrier of G by A88, NECKLACE:def 3;

            hence thesis;

          end;

          

           A91: u in Y1 by A48;

          reconsider u, v as Element of G by A82, ZFMISC_1: 87;

          

           A92: [v, x] in the InternalRel of G

          proof

            ex y1 be Element of R1 st v = y1 & [y1, x] in the InternalRel of G by A89;

            hence thesis;

          end;

          

           A93: w <> u

          proof

            assume

             A94: not thesis;

            (ex y1 be Element of R2 st w = y1 & [y1, x] in the InternalRel of G) & ex y2 be Element of R1 st u = y2 & not [y2, x] in the InternalRel of G by A91, A88;

            hence contradiction by A94;

          end;

          

           A95: not [u, x] in the InternalRel of G

          proof

            ex y1 be Element of R1 st u = y1 & not [y1, x] in the InternalRel of G by A91;

            hence thesis;

          end;

          

           A96: not [v, w] in the InternalRel of G

          proof

            

             A97: ex y2 be Element of R2 st w = y2 & [y2, x] in the InternalRel of G by A88;

            then w in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider w as Element of R by A2, NECKLA_2:def 2;

            

             A98: ex y1 be Element of R1 st v = y1 & [y1, x] in the InternalRel of G by A89;

            then v in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider v as Element of R by A2, NECKLA_2:def 2;

            assume not thesis;

            then [v, w] in (the InternalRel of G |_2 the carrier of R) by XBOOLE_0:def 4;

            then [v, w] in the InternalRel of R by YELLOW_0:def 14;

            then

             A99: [v, w] in (the InternalRel of R1 \/ the InternalRel of R2) by A2, NECKLA_2:def 2;

            per cases by A99, XBOOLE_0:def 3;

              suppose [v, w] in the InternalRel of R1;

              then w in the carrier of R1 by ZFMISC_1: 87;

              then w in (the carrier of R1 /\ the carrier of R2) by A97, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose [v, w] in the InternalRel of R2;

              then v in the carrier of R2 by ZFMISC_1: 87;

              then v in (the carrier of R1 /\ the carrier of R2) by A98, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

          end;

          

           A100: w <> x

          proof

            assume

             A101: not thesis;

            ex y1 be Element of R2 st w = y1 & [y1, x] in the InternalRel of G by A88;

            then x in (the carrier of R1 \/ the carrier of R2) by A101, XBOOLE_0:def 3;

            then x in the carrier of R by A2, NECKLA_2:def 2;

            then x in (the carrier of G \ {x}) by YELLOW_0:def 15;

            then not x in {x} by XBOOLE_0:def 5;

            hence contradiction by TARSKI:def 1;

          end;

          

           A102: not [u, w] in the InternalRel of G

          proof

            

             A103: ex y2 be Element of R2 st w = y2 & [y2, x] in the InternalRel of G by A88;

            then w in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider w as Element of R by A2, NECKLA_2:def 2;

            

             A104: ex y1 be Element of R1 st u = y1 & not [y1, x] in the InternalRel of G by A91;

            then u in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider u as Element of R by A2, NECKLA_2:def 2;

            assume not thesis;

            then [u, w] in (the InternalRel of G |_2 the carrier of R) by XBOOLE_0:def 4;

            then [u, w] in the InternalRel of R by YELLOW_0:def 14;

            then

             A105: [u, w] in (the InternalRel of R1 \/ the InternalRel of R2) by A2, NECKLA_2:def 2;

            per cases by A105, XBOOLE_0:def 3;

              suppose [u, w] in the InternalRel of R1;

              then w in the carrier of R1 by ZFMISC_1: 87;

              then w in (the carrier of R1 /\ the carrier of R2) by A103, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose [u, w] in the InternalRel of R2;

              then u in the carrier of R2 by ZFMISC_1: 87;

              then u in (the carrier of R1 /\ the carrier of R2) by A104, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

          end;

          

           A106: x <> u

          proof

            assume

             A107: not thesis;

            ex y1 be Element of R1 st u = y1 & not [y1, x] in the InternalRel of G by A91;

            then x in (the carrier of R1 \/ the carrier of R2) by A107, XBOOLE_0:def 3;

            then x in the carrier of R by A2, NECKLA_2:def 2;

            then x in (the carrier of G \ {x}) by YELLOW_0:def 15;

            then not x in {x} by XBOOLE_0:def 5;

            hence contradiction by TARSKI:def 1;

          end;

          

           A108: w <> v

          proof

            consider y1 be Element of R2 such that

             A109: w = y1 and [y1, x] in the InternalRel of G by A88;

            assume

             A110: not thesis;

            ex y2 be Element of R1 st v = y2 & [y2, x] in the InternalRel of G by A89;

            then y1 in (the carrier of R1 /\ the carrier of R2) by A110, A109, XBOOLE_0:def 4;

            hence contradiction by A1;

          end;

          

           A111: v <> x

          proof

            assume

             A112: not thesis;

            ex y1 be Element of R1 st v = y1 & [y1, x] in the InternalRel of G by A89;

            then x in (the carrier of R1 \/ the carrier of R2) by A112, XBOOLE_0:def 3;

            then x in the carrier of R by A2, NECKLA_2:def 2;

            then x in (the carrier of G \ {x}) by YELLOW_0:def 15;

            then not x in {x} by XBOOLE_0:def 5;

            hence contradiction by TARSKI:def 1;

          end;

          u <> v

          proof

            assume

             A113: not thesis;

            (ex y1 be Element of R1 st u = y1 & not [y1, x] in the InternalRel of G) & ex y2 be Element of R1 st v = y2 & [y2, x] in the InternalRel of G by A91, A89;

            hence contradiction by A113;

          end;

          then (u,v,x,w) are_mutually_distinct by A111, A106, A93, A108, A100, ZFMISC_1:def 6;

          then

           A114: ( subrelstr Z) embeds ( Necklace 4) by A82, A92, A90, A95, A102, A96, Th38;

          G embeds ( Necklace 4)

          proof

            assume not thesis;

            then G is N-free by NECKLA_2:def 1;

            then H is N-free by Th23;

            hence thesis by A114, NECKLA_2:def 1;

          end;

          hence thesis;

        end;

          suppose

           A115: Y2 is non empty;

          ex c be Element of Y2, d be Element of X2 st [c, d] in the InternalRel of G

          proof

            set c = the Element of Y2;

            b in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A116: b in the carrier of R by A2, NECKLA_2:def 2;

            c in Y2 by A115;

            then ex y be Element of R2 st y = c & not [y, x] in the InternalRel of G;

            then c in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A117: c in the carrier of R by A2, NECKLA_2:def 2;

            

             A118: the carrier of R c= the carrier of G by A19, XBOOLE_1: 7;

            then

            reconsider b as Element of G by A116;

            reconsider c as Element of G by A118, A117;

            b <> c

            proof

              assume not thesis;

              then c in X2 by A7;

              then c in (X2 /\ Y2) by A115, XBOOLE_0:def 4;

              hence contradiction by A14;

            end;

            then the InternalRel of G reduces (b,c) by A4;

            then

            consider p be FinSequence such that

             A119: ( len p) > 0 and

             A120: (p . 1) = b and

             A121: (p . ( len p)) = c and

             A122: for i be Nat st i in ( dom p) & (i + 1) in ( dom p) holds [(p . i), (p . (i + 1))] in the InternalRel of G by REWRITE1: 11;

            defpred P[ Nat] means (p . $1) in Y2 & $1 in ( dom p) & for k be Nat st k > $1 holds k in ( dom p) implies (p . k) in Y2;

            for k be Nat st k > ( len p) holds k in ( dom p) implies (p . k) in Y2

            proof

              let k be Nat such that

               A123: k > ( len p);

              assume k in ( dom p);

              then k in ( Seg ( len p)) by FINSEQ_1:def 3;

              hence thesis by A123, FINSEQ_1: 1;

            end;

            then P[( len p)] by A115, A119, A121, CARD_1: 27, FINSEQ_5: 6;

            then

             A124: ex k be Nat st P[k];

            ex n0 be Nat st P[n0] & for n be Nat st P[n] holds n >= n0 from NAT_1:sch 5( A124);

            then

            consider n0 be Nat such that

             A125: P[n0] and

             A126: for n be Nat st P[n] holds n >= n0;

            n0 <> 0

            proof

              assume not thesis;

              then 0 in ( Seg ( len p)) by A125, FINSEQ_1:def 3;

              hence contradiction by FINSEQ_1: 1;

            end;

            then

            consider k0 be Nat such that

             A127: n0 = (k0 + 1) by NAT_1: 6;

            

             A128: n0 <> 1

            proof

              assume

               A129: not thesis;

              b in X2 by A7;

              then (X2 /\ Y2) is non empty by A120, A125, A129, XBOOLE_0:def 4;

              hence contradiction by A14;

            end;

            

             A130: k0 >= 1

            proof

              assume not thesis;

              then k0 = 0 by NAT_1: 25;

              hence contradiction by A127, A128;

            end;

            n0 in ( Seg ( len p)) by A125, FINSEQ_1:def 3;

            then k0 <= (k0 + 1) & n0 <= ( len p) by FINSEQ_1: 1, XREAL_1: 29;

            then k0 <= ( len p) by A127, XXREAL_0: 2;

            then

             A131: k0 in ( Seg ( len p)) by A130, FINSEQ_1: 1;

            then

             A132: k0 in ( dom p) by FINSEQ_1:def 3;

            then

             A133: [(p . k0), (p . (k0 + 1))] in the InternalRel of G by A122, A125, A127;

            then

             A134: the InternalRel of G is_symmetric_in the carrier of G & (p . k0) in the carrier of G by NECKLACE:def 3, ZFMISC_1: 87;

            (p . n0) in the carrier of G by A127, A133, ZFMISC_1: 87;

            then

             A135: [(p . n0), (p . k0)] in the InternalRel of G by A127, A133, A134;

            

             A136: for k be Nat st k > k0 holds k in ( dom p) implies (p . k) in Y2

            proof

              assume not thesis;

              then

              consider k be Nat such that

               A137: k > k0 and

               A138: k in ( dom p) and

               A139: not (p . k) in Y2;

              k > n0

              proof

                per cases by XXREAL_0: 1;

                  suppose k < n0;

                  hence thesis by A127, A137, NAT_1: 13;

                end;

                  suppose n0 < k;

                  hence thesis;

                end;

                  suppose n0 = k;

                  hence thesis by A125, A139;

                end;

              end;

              hence contradiction by A125, A138, A139;

            end;

            k0 < n0 by A127, NAT_1: 13;

            then

             A140: not P[k0] by A126;

            (p . k0) in the carrier of G by A133, ZFMISC_1: 87;

            then (p . k0) in the carrier of R or (p . k0) in {x} by A19, XBOOLE_0:def 3;

            then

             A141: (p . k0) in (the carrier of R1 \/ the carrier of R2) or (p . k0) in {x} by A2, NECKLA_2:def 2;

            thus thesis

            proof

              per cases by A127, A133, A141, XBOOLE_0:def 3, ZFMISC_1: 87;

                suppose (p . k0) in the carrier of R2 & (p . n0) in the carrier of G;

                then

                reconsider m = (p . k0) as Element of X2 by A22, A131, A140, A136, FINSEQ_1:def 3, XBOOLE_0:def 3;

                reconsider l = (p . n0) as Element of Y2 by A125;

                 [m, l] in the InternalRel of G by A122, A125, A127, A132;

                hence thesis by A135;

              end;

                suppose (p . k0) in the carrier of R1 & (p . n0) in the carrier of G;

                then

                reconsider m = (p . k0) as Element of R1;

                reconsider l = (p . n0) as Element of R2 by A22, A125, XBOOLE_0:def 3;

                

                 A142: the InternalRel of R is_symmetric_in the carrier of R by NECKLACE:def 3;

                m in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

                then

                 A143: m in the carrier of R by A2, NECKLA_2:def 2;

                l in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

                then

                 A144: l in the carrier of R by A2, NECKLA_2:def 2;

                then [l, m] in [:the carrier of R, the carrier of R:] by A143, ZFMISC_1: 87;

                then [l, m] in (the InternalRel of G |_2 the carrier of R) by A135, XBOOLE_0:def 4;

                then [l, m] in the InternalRel of R by YELLOW_0:def 14;

                then [m, l] in the InternalRel of R by A144, A143, A142;

                hence thesis by A1, A2, Th35;

              end;

                suppose

                 A145: (p . k0) in {x} & (p . n0) in the carrier of G;

                ex y1 be Element of R2 st (p . n0) = y1 & not [y1, x] in the InternalRel of G by A125;

                hence thesis by A135, A145, TARSKI:def 1;

              end;

            end;

          end;

          then

          consider u be Element of Y2, v be Element of X2 such that

           A146: [u, v] in the InternalRel of G;

          set w = the Element of X1;

          w in X1 by A10;

          then

           A147: ex y be Element of R1 st y = w & [y, x] in the InternalRel of G;

          set Z = {u, v, x, w};

          Z c= the carrier of G

          proof

            w in X1 by A10;

            then ex y2 be Element of R1 st y2 = w & [y2, x] in the InternalRel of G;

            then w in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A148: w in the carrier of R by A2, NECKLA_2:def 2;

            v in X2 by A18;

            then ex y1 be Element of R2 st y1 = v & [y1, x] in the InternalRel of G;

            then v in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A149: v in the carrier of R by A2, NECKLA_2:def 2;

            u in the carrier of R2 by A22, A115, XBOOLE_0:def 3;

            then u in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

             A150: u in the carrier of R by A2, NECKLA_2:def 2;

            let q be object;

            assume q in Z;

            then

             A151: q = u or q = v or q = x or q = w by ENUMSET1:def 2;

            the carrier of R c= the carrier of G by A19, XBOOLE_1: 7;

            hence thesis by A151, A150, A149, A148;

          end;

          then

          reconsider Z as Subset of G;

          reconsider H = ( subrelstr Z) as non empty full SubRelStr of G by YELLOW_0:def 15;

          

           A152: w in X1 by A10;

          reconsider w as Element of G by A147, ZFMISC_1: 87;

          

           A153: v in X2 by A18;

          

           A154: [x, w] in the InternalRel of G

          proof

            (ex y1 be Element of R1 st w = y1 & [y1, x] in the InternalRel of G) & the InternalRel of G is_symmetric_in the carrier of G by A152, NECKLACE:def 3;

            hence thesis;

          end;

          

           A155: u in Y2 by A115;

          reconsider u, v as Element of G by A146, ZFMISC_1: 87;

          

           A156: [v, x] in the InternalRel of G

          proof

            ex y1 be Element of R2 st v = y1 & [y1, x] in the InternalRel of G by A153;

            hence thesis;

          end;

          

           A157: w <> u

          proof

            assume

             A158: not thesis;

            (ex y1 be Element of R1 st w = y1 & [y1, x] in the InternalRel of G) & ex y2 be Element of R2 st u = y2 & not [y2, x] in the InternalRel of G by A155, A152;

            hence contradiction by A158;

          end;

          

           A159: not [u, x] in the InternalRel of G

          proof

            ex y1 be Element of R2 st u = y1 & not [y1, x] in the InternalRel of G by A155;

            hence thesis;

          end;

          

           A160: not [v, w] in the InternalRel of G

          proof

            

             A161: ex y2 be Element of R1 st w = y2 & [y2, x] in the InternalRel of G by A152;

            then w in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider w as Element of R by A2, NECKLA_2:def 2;

            

             A162: ex y1 be Element of R2 st v = y1 & [y1, x] in the InternalRel of G by A153;

            then v in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider v as Element of R by A2, NECKLA_2:def 2;

            assume not thesis;

            then [v, w] in (the InternalRel of G |_2 the carrier of R) by XBOOLE_0:def 4;

            then [v, w] in the InternalRel of R by YELLOW_0:def 14;

            then

             A163: [v, w] in (the InternalRel of R1 \/ the InternalRel of R2) by A2, NECKLA_2:def 2;

            per cases by A163, XBOOLE_0:def 3;

              suppose [v, w] in the InternalRel of R1;

              then v in the carrier of R1 by ZFMISC_1: 87;

              then v in (the carrier of R1 /\ the carrier of R2) by A162, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose [v, w] in the InternalRel of R2;

              then w in the carrier of R2 by ZFMISC_1: 87;

              then w in (the carrier of R1 /\ the carrier of R2) by A161, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

          end;

          

           A164: w <> x

          proof

            assume

             A165: not thesis;

            ex y1 be Element of R1 st w = y1 & [y1, x] in the InternalRel of G by A152;

            then x in (the carrier of R1 \/ the carrier of R2) by A165, XBOOLE_0:def 3;

            then x in the carrier of R by A2, NECKLA_2:def 2;

            then x in (the carrier of G \ {x}) by YELLOW_0:def 15;

            then not x in {x} by XBOOLE_0:def 5;

            hence contradiction by TARSKI:def 1;

          end;

          

           A166: not [u, w] in the InternalRel of G

          proof

            

             A167: ex y2 be Element of R1 st w = y2 & [y2, x] in the InternalRel of G by A152;

            then w in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider w as Element of R by A2, NECKLA_2:def 2;

            

             A168: ex y1 be Element of R2 st u = y1 & not [y1, x] in the InternalRel of G by A155;

            then u in (the carrier of R1 \/ the carrier of R2) by XBOOLE_0:def 3;

            then

            reconsider u as Element of R by A2, NECKLA_2:def 2;

            assume not thesis;

            then [u, w] in (the InternalRel of G |_2 the carrier of R) by XBOOLE_0:def 4;

            then [u, w] in the InternalRel of R by YELLOW_0:def 14;

            then

             A169: [u, w] in (the InternalRel of R1 \/ the InternalRel of R2) by A2, NECKLA_2:def 2;

            per cases by A169, XBOOLE_0:def 3;

              suppose [u, w] in the InternalRel of R1;

              then u in the carrier of R1 by ZFMISC_1: 87;

              then u in (the carrier of R1 /\ the carrier of R2) by A168, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

              suppose [u, w] in the InternalRel of R2;

              then w in the carrier of R2 by ZFMISC_1: 87;

              then w in (the carrier of R1 /\ the carrier of R2) by A167, XBOOLE_0:def 4;

              hence contradiction by A1;

            end;

          end;

          

           A170: x <> u

          proof

            assume

             A171: not thesis;

            ex y1 be Element of R2 st u = y1 & not [y1, x] in the InternalRel of G by A155;

            then x in (the carrier of R1 \/ the carrier of R2) by A171, XBOOLE_0:def 3;

            then x in the carrier of R by A2, NECKLA_2:def 2;

            then x in (the carrier of G \ {x}) by YELLOW_0:def 15;

            then not x in {x} by XBOOLE_0:def 5;

            hence contradiction by TARSKI:def 1;

          end;

          

           A172: w <> v

          proof

            consider y1 be Element of R1 such that

             A173: w = y1 and [y1, x] in the InternalRel of G by A152;

            assume

             A174: not thesis;

            ex y2 be Element of R2 st v = y2 & [y2, x] in the InternalRel of G by A153;

            then y1 in (the carrier of R1 /\ the carrier of R2) by A174, A173, XBOOLE_0:def 4;

            hence contradiction by A1;

          end;

          

           A175: v <> x

          proof

            assume

             A176: not thesis;

            ex y1 be Element of R2 st v = y1 & [y1, x] in the InternalRel of G by A153;

            then x in (the carrier of R1 \/ the carrier of R2) by A176, XBOOLE_0:def 3;

            then x in the carrier of R by A2, NECKLA_2:def 2;

            then x in (the carrier of G \ {x}) by YELLOW_0:def 15;

            then not x in {x} by XBOOLE_0:def 5;

            hence contradiction by TARSKI:def 1;

          end;

          u <> v

          proof

            assume

             A177: not thesis;

            (ex y1 be Element of R2 st u = y1 & not [y1, x] in the InternalRel of G) & ex y2 be Element of R2 st v = y2 & [y2, x] in the InternalRel of G by A155, A153;

            hence contradiction by A177;

          end;

          then (u,v,x,w) are_mutually_distinct by A175, A170, A157, A172, A164, ZFMISC_1:def 6;

          then

           A178: ( subrelstr Z) embeds ( Necklace 4) by A146, A156, A154, A159, A166, A160, Th38;

          G embeds ( Necklace 4)

          proof

            assume not thesis;

            then G is N-free by NECKLA_2:def 1;

            then H is N-free by Th23;

            hence thesis by A178, NECKLA_2:def 1;

          end;

          hence thesis;

        end;

      end;

    end;

    theorem :: NECKLA_3:40

    for G be non empty strict finite irreflexive symmetric RelStr st G is N-free & the carrier of G in FinSETS holds the RelStr of G in fin_RelStr_sp

    proof

      let R be non empty strict finite irreflexive symmetric RelStr;

      defpred P[ Nat] means for G be non empty strict finite irreflexive symmetric RelStr st G is N-free & ( card the carrier of G) = $1 & the carrier of G in FinSETS holds the RelStr of G in fin_RelStr_sp ;

      

       A1: for n be Nat st for k be Nat st k < n holds P[k] holds P[n]

      proof

        let n be Nat such that

         A2: for k be Nat st k < n holds P[k];

        let G be non empty strict finite irreflexive symmetric RelStr;

        set CG = ( ComplRelStr G);

        assume that

         A3: G is N-free and

         A4: ( card the carrier of G) = n and

         A5: the carrier of G in FinSETS ;

        per cases ;

          suppose G is trivial;

          then the carrier of G is 1 -element;

          then

          reconsider G as 1 -element RelStr by STRUCT_0:def 19;

           the RelStr of G in fin_RelStr_sp by A5, NECKLA_2:def 5;

          hence thesis;

        end;

          suppose not G is path-connected & G is non trivial;

          then

          consider G1,G2 be non empty strict irreflexive symmetric RelStr such that

           A6: the carrier of G1 misses the carrier of G2 and

           A7: the RelStr of G = ( union_of (G1,G2)) by Th30;

          set cG1 = the carrier of G1, cG2 = the carrier of G2, R = the RelStr of G, cR = the carrier of R;

          reconsider cR as finite set;

          

           A8: cR = (cG1 \/ cG2) by A7, NECKLA_2:def 2;

          then

           A9: ( card cG1) in ( Segm ( card cR)) by A6, Lm1;

          then

          reconsider G1 as non empty strict finite irreflexive symmetric RelStr;

          reconsider cR as finite set;

          

           A10: ( card cG2) in ( Segm ( card cR)) by A6, A8, Lm1;

          then

          reconsider G2 as non empty strict finite irreflexive symmetric RelStr;

          reconsider cG2 as finite set by A10;

          

           A11: ( card cG2) < ( card cR) by A10, NAT_1: 44;

          G2 is full SubRelStr of G by A6, A7, Th10;

          then

           A12: G2 is N-free by A3, Th23;

          the carrier of G2 in FinSETS by A5, A8, CLASSES1: 3, CLASSES2:def 2, XBOOLE_1: 7;

          then

           A13: G2 in fin_RelStr_sp by A2, A4, A11, A12;

          G1 is full SubRelStr of G by A6, A7, Th10;

          then

           A14: G1 is N-free by A3, Th23;

          reconsider cG1 as finite set by A9;

          

           A15: ( card cG1) < ( card cR) by A9, NAT_1: 44;

          the carrier of G1 in FinSETS by A5, A8, CLASSES1: 3, CLASSES2:def 2, XBOOLE_1: 7;

          then G1 in fin_RelStr_sp by A2, A4, A15, A14;

          hence thesis by A6, A7, A13, NECKLA_2:def 5;

        end;

          suppose not CG is path-connected & G is non trivial;

          then

          consider G1,G2 be non empty strict irreflexive symmetric RelStr such that

           A16: the carrier of G1 misses the carrier of G2 and

           A17: the RelStr of G = ( sum_of (G1,G2)) by Th31;

          set cG1 = the carrier of G1, cG2 = the carrier of G2, R = the RelStr of G, cR = the carrier of R;

          reconsider cR as finite set;

          

           A18: cR = (cG1 \/ cG2) by A17, NECKLA_2:def 3;

          then

           A19: ( card cG1) in ( Segm ( card cR)) by A16, Lm1;

          then

          reconsider G1 as non empty strict finite irreflexive symmetric RelStr;

          

           A20: ( card cG2) in ( Segm ( card cR)) by A16, A18, Lm1;

          then

          reconsider G2 as non empty strict finite irreflexive symmetric RelStr;

          reconsider cG2 as finite set by A20;

          

           A21: ( card cG2) < ( card cR) by A20, NAT_1: 44;

          G2 is full SubRelStr of G by A16, A17, Th10;

          then

           A22: G2 is N-free by A3, Th23;

          the carrier of G2 in FinSETS by A5, A18, CLASSES1: 3, CLASSES2:def 2, XBOOLE_1: 7;

          then

           A23: G2 in fin_RelStr_sp by A2, A4, A21, A22;

          G1 is full SubRelStr of G by A16, A17, Th10;

          then

           A24: G1 is N-free by A3, Th23;

          reconsider cG1 as finite set by A19;

          

           A25: ( card cG1) < ( card cR) by A19, NAT_1: 44;

          the carrier of G1 in FinSETS by A5, A18, CLASSES1: 3, CLASSES2:def 2, XBOOLE_1: 7;

          then G1 in fin_RelStr_sp by A2, A4, A25, A24;

          hence thesis by A16, A17, A23, NECKLA_2:def 5;

        end;

          suppose

           A26: G is non trivial & G is path-connected & CG is path-connected;

          consider x be object such that

           A27: x in the carrier of G by XBOOLE_0:def 1;

          reconsider x as Element of G by A27;

          set A = (the carrier of G \ {x});

          

           A28: A c= the carrier of G;

          reconsider A as Subset of G;

          set R = ( subrelstr A);

          reconsider R as non empty finite irreflexive symmetric RelStr by A26, YELLOW_0:def 15;

          

           A29: the carrier of R c= the carrier of G by A28, YELLOW_0:def 15;

          ( card A) = (( card the carrier of G) - ( card {x})) by CARD_2: 44;

          then

           A30: ( card A) = (n - 1) by A4, CARD_2: 42;

          (n - 1) < ((n - 1) + 1) by XREAL_1: 29;

          then

           A31: ( card the carrier of R) < n by A30, YELLOW_0:def 15;

          R is N-free by A3, Th23;

          then

           A32: R in fin_RelStr_sp by A2, A5, A31, A29, CLASSES1: 3, CLASSES2:def 2;

          thus thesis

          proof

            per cases by A32, NECKLA_2: 6;

              suppose

               A33: R is trivial RelStr;

              the carrier of R is non empty;

              then

               A34: A is non empty by YELLOW_0:def 15;

              A is trivial by A33, YELLOW_0:def 15;

              then

              consider a be object such that

               A35: A = {a} by A34, ZFMISC_1: 131;

              

               A36: (the carrier of G \/ {x}) = the carrier of G

              proof

                thus (the carrier of G \/ {x}) c= the carrier of G

                proof

                  let c be object;

                  assume c in (the carrier of G \/ {x});

                  then c in the carrier of G or c in {x} by XBOOLE_0:def 3;

                  hence thesis;

                end;

                let c be object;

                assume c in the carrier of G;

                hence thesis by XBOOLE_0:def 3;

              end;

              ( {a} \/ {x}) = (the carrier of G \/ {x}) by A35, XBOOLE_1: 39;

              then the carrier of G = {a, x} & a <> x by A26, A36, ENUMSET1: 1;

              then ( card the carrier of G) = 2 by CARD_2: 57;

              hence thesis by A5, Th33;

            end;

              suppose ex R1,R2 be strict RelStr st the carrier of R1 misses the carrier of R2 & R1 in fin_RelStr_sp & R2 in fin_RelStr_sp & (R = ( union_of (R1,R2)) or R = ( sum_of (R1,R2)));

              then

              consider R1,R2 be strict RelStr such that

               A37: the carrier of R1 misses the carrier of R2 and

               A38: R1 in fin_RelStr_sp and

               A39: R2 in fin_RelStr_sp and

               A40: R = ( union_of (R1,R2)) or R = ( sum_of (R1,R2));

              thus thesis

              proof

                per cases by A40;

                  suppose

                   A41: R = ( union_of (R1,R2));

                  R2 is SubRelStr of R by A37, A40, Th10;

                  then

                  reconsider R2 as non empty SubRelStr of G by A39, NECKLA_2: 4, YELLOW_6: 7;

                  R1 is SubRelStr of R by A37, A40, Th10;

                  then

                  reconsider R1 as non empty SubRelStr of G by A38, NECKLA_2: 4, YELLOW_6: 7;

                  ( subrelstr (( [#] G) \ {x})) = ( union_of (R1,R2)) by A41;

                  then G embeds ( Necklace 4) by A26, A37, Th39;

                  hence thesis by A3, NECKLA_2:def 1;

                end;

                  suppose

                   A42: R = ( sum_of (R1,R2));

                  ( ComplRelStr R2) is non empty

                  proof

                    assume not thesis;

                    then R2 is empty;

                    hence contradiction by A39, NECKLA_2: 4;

                  end;

                  then

                  reconsider R22 = ( ComplRelStr R2) as non empty RelStr;

                  ( ComplRelStr R1) is non empty

                  proof

                    assume not thesis;

                    then R1 is empty;

                    hence contradiction by A38, NECKLA_2: 4;

                  end;

                  then

                  reconsider R11 = ( ComplRelStr R1) as non empty RelStr;

                  reconsider G9 = ( ComplRelStr G) as non empty irreflexive symmetric RelStr;

                  reconsider x9 = x as Element of G9 by NECKLACE:def 8;

                  

                   A43: the carrier of R11 = the carrier of R1 & the carrier of R22 = the carrier of R2 by NECKLACE:def 8;

                  

                   A44: ( ComplRelStr R) = ( ComplRelStr ( subrelstr (( [#] G) \ {x})))

                  .= ( subrelstr (( [#] G9) \ {x9})) by Th20;

                  

                   A45: G9 is N-free by A3, Th25;

                  

                   A46: ( ComplRelStr G9) is path-connected & G9 is non trivial by A26, Th16, NECKLACE:def 8;

                  ( ComplRelStr R) = ( union_of (( ComplRelStr R1),( ComplRelStr R2))) by A37, A42, Th18;

                  then G9 embeds ( Necklace 4) by A26, A37, A43, A46, A44, Th39;

                  hence thesis by A45, NECKLA_2:def 1;

                end;

              end;

            end;

          end;

        end;

      end;

      

       A47: for k be Nat holds P[k] from NAT_1:sch 4( A1);

      ( card the carrier of R) is Nat;

      hence thesis by A47;

    end;