yellow_3.miz



    begin

    scheme :: YELLOW_3:sch1

    FraenkelA2 { A() -> non empty set , F( set, set) -> set , P[ set, set], Q[ set, set] } :

{ F(s,t) where s be Element of A(), t be Element of A() : P[s, t] } is Subset of A()

      provided

       A1: for s be Element of A(), t be Element of A() holds F(s,t) in A();

      { F(s,t) where s be Element of A(), t be Element of A() : P[s, t] } c= A()

      proof

        let q be object;

        assume q in { F(s,t) where s be Element of A(), t be Element of A() : P[s, t] };

        then ex s,t be Element of A() st q = F(s,t) & P[s, t];

        hence thesis by A1;

      end;

      hence thesis;

    end;

    registration

      let L be RelStr, X be empty Subset of L;

      cluster ( downarrow X) -> empty;

      coherence

      proof

        assume ( downarrow X) is non empty;

        then

        consider x be object such that

         A1: x in ( downarrow X) by XBOOLE_0:def 1;

        reconsider x as Element of L by A1;

        ex z be Element of L st x <= z & z in X by A1, WAYBEL_0:def 15;

        hence contradiction;

      end;

      cluster ( uparrow X) -> empty;

      coherence

      proof

        assume ( uparrow X) is non empty;

        then

        consider x be object such that

         A2: x in ( uparrow X) by XBOOLE_0:def 1;

        reconsider x as Element of L by A2;

        ex z be Element of L st z <= x & z in X by A2, WAYBEL_0:def 16;

        hence contradiction;

      end;

    end

    theorem :: YELLOW_3:1

    

     Th1: for X,Y be set, D be Subset of [:X, Y:] holds D c= [:( proj1 D), ( proj2 D):]

    proof

      let X,Y be set, D be Subset of [:X, Y:];

      let q be object;

      assume

       A1: q in D;

      then

      consider x,y be object such that x in X and y in Y and

       A2: q = [x, y] by ZFMISC_1:def 2;

      x in ( proj1 D) & y in ( proj2 D) by A1, A2, XTUPLE_0:def 12, XTUPLE_0:def 13;

      hence thesis by A2, ZFMISC_1:def 2;

    end;

    theorem :: YELLOW_3:2

    for L be with_infima transitive antisymmetric RelStr holds for a,b,c,d be Element of L st a <= c & b <= d holds (a "/\" b) <= (c "/\" d)

    proof

      let L be with_infima transitive antisymmetric RelStr, a,b,c,d be Element of L such that

       A1: a <= c and

       A2: b <= d;

      

       A3: ex_inf_of ( {a, b},L) by YELLOW_0: 21;

      then (a "/\" b) <= b by YELLOW_0: 19;

      then

       A4: (a "/\" b) <= d by A2, ORDERS_2: 3;

      (a "/\" b) <= a by A3, YELLOW_0: 19;

      then (ex x be Element of L st c >= x & d >= x & for z be Element of L st c >= z & d >= z holds x >= z) & (a "/\" b) <= c by A1, LATTICE3:def 11, ORDERS_2: 3;

      hence thesis by A4, LATTICE3:def 14;

    end;

    theorem :: YELLOW_3:3

    for L be with_suprema transitive antisymmetric RelStr holds for a,b,c,d be Element of L st a <= c & b <= d holds (a "\/" b) <= (c "\/" d)

    proof

      let L be with_suprema transitive antisymmetric RelStr, a,b,c,d be Element of L such that

       A1: a <= c and

       A2: b <= d;

      

       A3: ex_sup_of ( {c, d},L) by YELLOW_0: 20;

      then d <= (c "\/" d) by YELLOW_0: 18;

      then

       A4: b <= (c "\/" d) by A2, ORDERS_2: 3;

      c <= (c "\/" d) by A3, YELLOW_0: 18;

      then (ex x be Element of L st a <= x & b <= x & for z be Element of L st a <= z & b <= z holds x <= z) & a <= (c "\/" d) by A1, LATTICE3:def 10, ORDERS_2: 3;

      hence thesis by A4, LATTICE3:def 13;

    end;

    theorem :: YELLOW_3:4

    for L be complete reflexive antisymmetric non empty RelStr holds for D be Subset of L, x be Element of L st x in D holds (( sup D) "/\" x) = x

    proof

      let L be complete reflexive antisymmetric non empty RelStr, D be Subset of L, x be Element of L such that

       A1: x in D;

      D is_<=_than ( sup D) by YELLOW_0: 32;

      then x <= ( sup D) by A1;

      hence thesis by YELLOW_0: 25;

    end;

    theorem :: YELLOW_3:5

    for L be complete reflexive antisymmetric non empty RelStr holds for D be Subset of L, x be Element of L st x in D holds (( inf D) "\/" x) = x

    proof

      let L be complete reflexive antisymmetric non empty RelStr, D be Subset of L, x be Element of L such that

       A1: x in D;

      D is_>=_than ( inf D) by YELLOW_0: 33;

      then ( inf D) <= x by A1;

      hence thesis by YELLOW_0: 24;

    end;

    theorem :: YELLOW_3:6

    for L be RelStr, X,Y be Subset of L st X c= Y holds ( downarrow X) c= ( downarrow Y)

    proof

      let L be RelStr, X,Y be Subset of L such that

       A1: X c= Y;

      let q be object;

      assume

       A2: q in ( downarrow X);

      then

      reconsider x = q as Element of L;

      ex z be Element of L st x <= z & z in X by A2, WAYBEL_0:def 15;

      hence thesis by A1, WAYBEL_0:def 15;

    end;

    theorem :: YELLOW_3:7

    for L be RelStr, X,Y be Subset of L st X c= Y holds ( uparrow X) c= ( uparrow Y)

    proof

      let L be RelStr, X,Y be Subset of L such that

       A1: X c= Y;

      let q be object;

      assume

       A2: q in ( uparrow X);

      then

      reconsider x = q as Element of L;

      ex z be Element of L st z <= x & z in X by A2, WAYBEL_0:def 16;

      hence thesis by A1, WAYBEL_0:def 16;

    end;

    theorem :: YELLOW_3:8

    for S,T be with_infima Poset, f be Function of S, T holds for x,y be Element of S holds f preserves_inf_of {x, y} iff (f . (x "/\" y)) = ((f . x) "/\" (f . y))

    proof

      let S,T be with_infima Poset, f be Function of S, T, x,y be Element of S;

      

       A1: ( dom f) = the carrier of S by FUNCT_2:def 1;

      hereby

        

         A2: ex_inf_of ( {x, y},S) by YELLOW_0: 21;

        assume

         A3: f preserves_inf_of {x, y};

        

        thus (f . (x "/\" y)) = (f . ( inf {x, y})) by YELLOW_0: 40

        .= ( inf (f .: {x, y})) by A3, A2

        .= ( inf {(f . x), (f . y)}) by A1, FUNCT_1: 60

        .= ((f . x) "/\" (f . y)) by YELLOW_0: 40;

      end;

      assume

       A4: (f . (x "/\" y)) = ((f . x) "/\" (f . y));

      assume ex_inf_of ( {x, y},S);

      (f .: {x, y}) = {(f . x), (f . y)} by A1, FUNCT_1: 60;

      hence ex_inf_of ((f .: {x, y}),T) by YELLOW_0: 21;

      

      thus ( inf (f .: {x, y})) = ( inf {(f . x), (f . y)}) by A1, FUNCT_1: 60

      .= ((f . x) "/\" (f . y)) by YELLOW_0: 40

      .= (f . ( inf {x, y})) by A4, YELLOW_0: 40;

    end;

    theorem :: YELLOW_3:9

    for S,T be with_suprema Poset, f be Function of S, T holds for x,y be Element of S holds f preserves_sup_of {x, y} iff (f . (x "\/" y)) = ((f . x) "\/" (f . y))

    proof

      let S,T be with_suprema Poset, f be Function of S, T, x,y be Element of S;

      

       A1: ( dom f) = the carrier of S by FUNCT_2:def 1;

      hereby

        

         A2: ex_sup_of ( {x, y},S) by YELLOW_0: 20;

        assume

         A3: f preserves_sup_of {x, y};

        

        thus (f . (x "\/" y)) = (f . ( sup {x, y})) by YELLOW_0: 41

        .= ( sup (f .: {x, y})) by A3, A2

        .= ( sup {(f . x), (f . y)}) by A1, FUNCT_1: 60

        .= ((f . x) "\/" (f . y)) by YELLOW_0: 41;

      end;

      assume

       A4: (f . (x "\/" y)) = ((f . x) "\/" (f . y));

      assume ex_sup_of ( {x, y},S);

      (f .: {x, y}) = {(f . x), (f . y)} by A1, FUNCT_1: 60;

      hence ex_sup_of ((f .: {x, y}),T) by YELLOW_0: 20;

      

      thus ( sup (f .: {x, y})) = ( sup {(f . x), (f . y)}) by A1, FUNCT_1: 60

      .= ((f . x) "\/" (f . y)) by YELLOW_0: 41

      .= (f . ( sup {x, y})) by A4, YELLOW_0: 41;

    end;

    scheme :: YELLOW_3:sch2

    InfUnion { L() -> complete antisymmetric non empty RelStr , P[ set] } :

( "/\" ({ ( "/\" (X,L())) where X be Subset of L() : P[X] },L())) >= ( "/\" (( union { X where X be Subset of L() : P[X] }),L()));

      ( "/\" (( union { X where X be Subset of L() : P[X] }),L())) is_<=_than { ( "/\" (X,L())) where X be Subset of L() : P[X] }

      proof

        let a be Element of L();

        assume a in { ( "/\" (X,L())) where X be Subset of L() : P[X] };

        then

        consider q be Subset of L() such that

         A1: a = ( "/\" (q,L())) and

         A2: P[q];

        

         A3: ex_inf_of (q,L()) & ex_inf_of (( union { X where X be Subset of L() : P[X] }),L()) by YELLOW_0: 17;

        q in { X where X be Subset of L() : P[X] } by A2;

        hence thesis by A1, A3, YELLOW_0: 35, ZFMISC_1: 74;

      end;

      hence thesis by YELLOW_0: 33;

    end;

    scheme :: YELLOW_3:sch3

    InfofInfs { L() -> complete LATTICE , P[ set] } :

( "/\" ({ ( "/\" (X,L())) where X be Subset of L() : P[X] },L())) = ( "/\" (( union { X where X be Subset of L() : P[X] }),L()));

      ( union { X where X be Subset of L() : P[X] }) is_>=_than ( "/\" ({ ( "/\" (X,L())) where X be Subset of L() : P[X] },L()))

      proof

        let a be Element of L();

        assume a in ( union { X where X be Subset of L() : P[X] });

        then

        consider b be set such that

         A1: a in b and

         A2: b in { X where X be Subset of L() : P[X] } by TARSKI:def 4;

        consider c be Subset of L() such that

         A3: b = c and

         A4: P[c] by A2;

        ( "/\" (c,L())) in { ( "/\" (X,L())) where X be Subset of L() : P[X] } by A4;

        then

         A5: ( "/\" (c,L())) >= ( "/\" ({ ( "/\" (X,L())) where X be Subset of L() : P[X] },L())) by YELLOW_2: 22;

        ( "/\" (c,L())) <= a by A1, A3, YELLOW_2: 22;

        hence thesis by A5, YELLOW_0:def 2;

      end;

      then

       A6: ( "/\" (( union { X where X be Subset of L() : P[X] }),L())) >= ( "/\" ({ ( "/\" (X,L())) where X be Subset of L() : P[X] },L())) by YELLOW_0: 33;

      ( "/\" ({ ( "/\" (X,L())) where X be Subset of L() : P[X] },L())) >= ( "/\" (( union { X where X be Subset of L() : P[X] }),L())) from InfUnion;

      hence thesis by A6, ORDERS_2: 2;

    end;

    scheme :: YELLOW_3:sch4

    SupUnion { L() -> complete antisymmetric non empty RelStr , P[ set] } :

( "\/" ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L())) <= ( "\/" (( union { X where X be Subset of L() : P[X] }),L()));

      

       A1: ( "\/" (( union { X where X be Subset of L() : P[X] }),L())) is_>=_than { ( "\/" (X,L())) where X be Subset of L() : P[X] }

      proof

        let a be Element of L();

        assume a in { ( "\/" (X,L())) where X be Subset of L() : P[X] };

        then

        consider q be Subset of L() such that

         A2: a = ( "\/" (q,L())) and

         A3: P[q];

        

         A4: ex_sup_of (q,L()) & ex_sup_of (( union { X where X be Subset of L() : P[X] }),L()) by YELLOW_0: 17;

        q in { X where X be Subset of L() : P[X] } by A3;

        hence thesis by A2, A4, YELLOW_0: 34, ZFMISC_1: 74;

      end;

       ex_sup_of ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L()) by YELLOW_0: 17;

      hence thesis by A1, YELLOW_0:def 9;

    end;

    scheme :: YELLOW_3:sch5

    SupofSups { L() -> complete LATTICE , P[ set] } :

( "\/" ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L())) = ( "\/" (( union { X where X be Subset of L() : P[X] }),L()));

      

       A1: ( union { X where X be Subset of L() : P[X] }) is_<=_than ( "\/" ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L()))

      proof

        let a be Element of L();

        assume a in ( union { X where X be Subset of L() : P[X] });

        then

        consider b be set such that

         A2: a in b and

         A3: b in { X where X be Subset of L() : P[X] } by TARSKI:def 4;

        consider c be Subset of L() such that

         A4: b = c and

         A5: P[c] by A3;

        ( "\/" (c,L())) in { ( "\/" (X,L())) where X be Subset of L() : P[X] } by A5;

        then

         A6: ( "\/" (c,L())) <= ( "\/" ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L())) by YELLOW_2: 22;

        a <= ( "\/" (c,L())) by A2, A4, YELLOW_2: 22;

        hence a <= ( "\/" ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L())) by A6, YELLOW_0:def 2;

      end;

      

       A7: ( "\/" ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L())) <= ( "\/" (( union { X where X be Subset of L() : P[X] }),L())) from SupUnion;

       ex_sup_of (( union { X where X be Subset of L() : P[X] }),L()) by YELLOW_0: 17;

      then ( "\/" (( union { X where X be Subset of L() : P[X] }),L())) <= ( "\/" ({ ( "\/" (X,L())) where X be Subset of L() : P[X] },L())) by A1, YELLOW_0:def 9;

      hence thesis by A7, ORDERS_2: 2;

    end;

    begin

    definition

      let P,R be Relation;

      :: YELLOW_3:def1

      func ["P,R"] -> Relation means

      : Def1: for x,y be object holds [x, y] in it iff ex p,q,s,t be object st x = [p, q] & y = [s, t] & [p, s] in P & [q, t] in R;

      existence

      proof

        defpred P[ object, object] means ex p,s,q,t be object st $1 = [p, q] & $2 = [s, t] & [p, s] in P & [q, t] in R;

        consider Q be Relation such that

         A1: for x,y be object holds [x, y] in Q iff x in [:( dom P), ( dom R):] & y in [:( rng P), ( rng R):] & P[x, y] from RELAT_1:sch 1;

        take Q;

        let x,y be object;

        hereby

          assume [x, y] in Q;

          then

          consider p,s,q,t be object such that

           A2: x = [p, q] & y = [s, t] & [p, s] in P & [q, t] in R by A1;

          take p, q, s, t;

          thus x = [p, q] & y = [s, t] & [p, s] in P & [q, t] in R by A2;

        end;

        given p,q,s,t be object such that

         A3: x = [p, q] and

         A4: y = [s, t] and

         A5: [p, s] in P & [q, t] in R;

        s in ( rng P) & t in ( rng R) by A5, XTUPLE_0:def 13;

        then

         A6: y in [:( rng P), ( rng R):] by A4, ZFMISC_1: 87;

        p in ( dom P) & q in ( dom R) by A5, XTUPLE_0:def 12;

        then x in [:( dom P), ( dom R):] by A3, ZFMISC_1: 87;

        hence thesis by A1, A3, A4, A5, A6;

      end;

      uniqueness

      proof

        defpred P[ object, object] means ex p,q,s,t be object st $1 = [p, q] & $2 = [s, t] & [p, s] in P & [q, t] in R;

        let A,B be Relation such that

         A7: for x,y be object holds [x, y] in A iff P[x, y] and

         A8: for x,y be object holds [x, y] in B iff P[x, y];

        thus A = B from RELAT_1:sch 2( A7, A8);

      end;

    end

    theorem :: YELLOW_3:10

    

     Th10: for P,R be Relation, x be object holds x in ["P, R"] iff [((x `1 ) `1 ), ((x `2 ) `1 )] in P & [((x `1 ) `2 ), ((x `2 ) `2 )] in R & (ex a,b be object st x = [a, b]) & (ex c,d be object st (x `1 ) = [c, d]) & ex e,f be object st (x `2 ) = [e, f]

    proof

      let P,R be Relation, x be object;

      hereby

        assume

         A1: x in ["P, R"];

        then

        consider y,z be object such that

         A2: x = [y, z] by RELAT_1:def 1;

        consider p,q,s,t be object such that

         A3: y = [p, q] and

         A4: z = [s, t] and

         A5: [p, s] in P & [q, t] in R by A1, A2, Def1;

        ((x `1 ) `1 ) = p & ((x `1 ) `2 ) = q by A2, A3;

        hence [((x `1 ) `1 ), ((x `2 ) `1 )] in P & [((x `1 ) `2 ), ((x `2 ) `2 )] in R by A2, A4, A5;

        thus ex a,b be object st x = [a, b] by A2;

        thus ex c,d be object st (x `1 ) = [c, d] by A2, A3;

        thus ex e,f be object st (x `2 ) = [e, f] by A2, A4;

      end;

      assume that

       A6: [((x `1 ) `1 ), ((x `2 ) `1 )] in P and

       A7: [((x `1 ) `2 ), ((x `2 ) `2 )] in R;

      given a,b be object such that

       A8: x = [a, b];

      given c,d be object such that

       A9: (x `1 ) = [c, d];

      given e,f be object such that

       A10: (x `2 ) = [e, f];

       [c, ((x `2 ) `1 )] in P by A6, A9;

      then

       A11: [c, e] in P by A10;

       [d, ((x `2 ) `2 )] in R by A7, A9;

      then

       A12: [d, f] in R by A10;

      

       A13: b = [e, f] by A8, A10;

      a = [c, d] by A8, A9;

      hence thesis by A8, A13, A11, A12, Def1;

    end;

    definition

      let A,B,X,Y be set;

      let P be Relation of A, B;

      let R be Relation of X, Y;

      :: original: ["

      redefine

      func ["P,R"] -> Relation of [:A, X:], [:B, Y:] ;

      coherence

      proof

         ["P, R"] c= [: [:A, X:], [:B, Y:]:]

        proof

          let q be object;

          assume

           A1: q in ["P, R"];

          then

          consider a,b be object such that

           A2: q = [a, b] by Th10;

           [((q `1 ) `2 ), ((q `2 ) `2 )] in R by A1, Th10;

          then

          consider s,t be object such that

           A3: [((q `1 ) `2 ), ((q `2 ) `2 )] = [s, t] and

           A4: s in X and

           A5: t in Y by RELSET_1: 2;

          consider a2,b2 be object such that

           A6: (q `2 ) = [a2, b2] by A1, Th10;

           [((q `1 ) `1 ), ((q `2 ) `1 )] in P by A1, Th10;

          then

          consider x,y be object such that

           A7: [((q `1 ) `1 ), ((q `2 ) `1 )] = [x, y] and

           A8: x in A and

           A9: y in B by RELSET_1: 2;

          consider a1,b1 be object such that

           A10: (q `1 ) = [a1, b1] by A1, Th10;

          

           A11: b = [a2, b2] by A2, A6;

          then

           A12: (b `2 ) = t by A3, A6, XTUPLE_0: 1;

          

           A13: a = [a1, b1] by A2, A10;

          then

           A14: (a `2 ) = s by A3, A10, XTUPLE_0: 1;

          (b `1 ) = y by A7, A6, A11, XTUPLE_0: 1;

          then

           A15: b in [:B, Y:] by A9, A5, A11, A12, ZFMISC_1:def 2;

          (a `1 ) = x by A7, A10, A13, XTUPLE_0: 1;

          then a in [:A, X:] by A8, A4, A13, A14, ZFMISC_1:def 2;

          hence thesis by A2, A15, ZFMISC_1:def 2;

        end;

        hence thesis;

      end;

    end

    definition

      let X,Y be RelStr;

      :: YELLOW_3:def2

      func [:X,Y:] -> strict RelStr means

      : Def2: the carrier of it = [:the carrier of X, the carrier of Y:] & the InternalRel of it = ["the InternalRel of X, the InternalRel of Y"];

      existence

      proof

        take RelStr (# [:the carrier of X, the carrier of Y:], ["the InternalRel of X, the InternalRel of Y"] #);

        thus thesis;

      end;

      uniqueness ;

    end

    definition

      let L1,L2 be RelStr, D be Subset of [:L1, L2:];

      :: original: proj1

      redefine

      func proj1 D -> Subset of L1 ;

      coherence

      proof

        ( proj1 D) c= the carrier of L1

        proof

          let x be object;

          assume x in ( proj1 D);

          then

           A1: ex y be object st [x, y] in D by XTUPLE_0:def 12;

          the carrier of [:L1, L2:] = [:the carrier of L1, the carrier of L2:] by Def2;

          hence thesis by A1, ZFMISC_1: 87;

        end;

        hence thesis;

      end;

      :: original: proj2

      redefine

      func proj2 D -> Subset of L2 ;

      coherence

      proof

        ( proj2 D) c= the carrier of L2

        proof

          let y be object;

          assume y in ( proj2 D);

          then

           A2: ex x be object st [x, y] in D by XTUPLE_0:def 13;

          the carrier of [:L1, L2:] = [:the carrier of L1, the carrier of L2:] by Def2;

          hence thesis by A2, ZFMISC_1: 87;

        end;

        hence thesis;

      end;

    end

    definition

      let S1,S2 be RelStr, D1 be Subset of S1, D2 be Subset of S2;

      :: original: [:

      redefine

      func [:D1,D2:] -> Subset of [:S1, S2:] ;

      coherence

      proof

         [:D1, D2:] c= [:the carrier of S1, the carrier of S2:];

        hence thesis by Def2;

      end;

    end

    definition

      let S1,S2 be non empty RelStr, x be Element of S1, y be Element of S2;

      :: original: [

      redefine

      func [x,y] -> Element of [:S1, S2:] ;

      coherence

      proof

        reconsider y1 = y as Element of S2;

        reconsider x1 = x as Element of S1;

         [x1, y1] is Element of [:S1, S2:] by Def2;

        hence thesis;

      end;

    end

    definition

      let L1,L2 be non empty RelStr, x be Element of [:L1, L2:];

      :: original: `1

      redefine

      func x `1 -> Element of L1 ;

      coherence

      proof

        the carrier of [:L1, L2:] = [:the carrier of L1, the carrier of L2:] by Def2;

        hence thesis by MCART_1: 10;

      end;

      :: original: `2

      redefine

      func x `2 -> Element of L2 ;

      coherence

      proof

        the carrier of [:L1, L2:] = [:the carrier of L1, the carrier of L2:] by Def2;

        hence thesis by MCART_1: 10;

      end;

    end

    theorem :: YELLOW_3:11

    

     Th11: for S1,S2 be non empty RelStr holds for a,c be Element of S1, b,d be Element of S2 holds a <= c & b <= d iff [a, b] <= [c, d]

    proof

      let S1,S2 be non empty RelStr, a,c be Element of S1, b,d be Element of S2;

      set I1 = the InternalRel of S1, I2 = the InternalRel of S2, x = [ [a, b], [c, d]];

      

       A1: ((x `1 ) `1 ) = a & ((x `2 ) `1 ) = c;

      

       A2: ((x `1 ) `2 ) = b & ((x `2 ) `2 ) = d;

      thus a <= c & b <= d implies [a, b] <= [c, d]

      proof

        assume a <= c & b <= d;

        then [((x `1 ) `1 ), ((x `2 ) `1 )] in I1 & [((x `1 ) `2 ), ((x `2 ) `2 )] in I2;

        then x in ["I1, I2"] by Th10;

        hence [ [a, b], [c, d]] in the InternalRel of [:S1, S2:] by Def2;

      end;

      assume [a, b] <= [c, d];

      then x in the InternalRel of [:S1, S2:];

      then x in ["I1, I2"] by Def2;

      hence [a, c] in the InternalRel of S1 & [b, d] in the InternalRel of S2 by A1, A2, Th10;

    end;

    theorem :: YELLOW_3:12

    

     Th12: for S1,S2 be non empty RelStr, x,y be Element of [:S1, S2:] holds x <= y iff (x `1 ) <= (y `1 ) & (x `2 ) <= (y `2 )

    proof

      let S1,S2 be non empty RelStr, x,y be Element of [:S1, S2:];

      

       A1: the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then ex c,d be object st c in the carrier of S1 & d in the carrier of S2 & y = [c, d] by ZFMISC_1:def 2;

      then

       A2: y = [(y `1 ), (y `2 )];

      ex a,b be object st a in the carrier of S1 & b in the carrier of S2 & x = [a, b] by A1, ZFMISC_1:def 2;

      then x = [(x `1 ), (x `2 )];

      hence thesis by A2, Th11;

    end;

    theorem :: YELLOW_3:13

    for A,B be RelStr, C be non empty RelStr holds for f,g be Function of [:A, B:], C st for x be Element of A, y be Element of B holds (f . (x,y)) = (g . (x,y)) holds f = g

    proof

      let A,B be RelStr, C be non empty RelStr, f,g be Function of [:A, B:], C;

      assume for x be Element of A, y be Element of B holds (f . (x,y)) = (g . (x,y));

      then

       A1: for x,y be set st x in the carrier of A & y in the carrier of B holds (f . (x,y)) = (g . (x,y));

      the carrier of [:A, B:] = [:the carrier of A, the carrier of B:] by Def2;

      hence thesis by A1, BINOP_1: 1;

    end;

    registration

      let X,Y be non empty RelStr;

      cluster [:X, Y:] -> non empty;

      coherence

      proof

        set y = the Element of Y;

        set x = the Element of X;

         [x, y] in [:the carrier of X, the carrier of Y:] by ZFMISC_1: 87;

        hence thesis by Def2;

      end;

    end

    registration

      let X,Y be reflexive RelStr;

      cluster [:X, Y:] -> reflexive;

      coherence

      proof

        let x be object;

        assume x in the carrier of [:X, Y:];

        then x in [:the carrier of X, the carrier of Y:] by Def2;

        then

        consider x1,x2 be object such that

         A1: x1 in the carrier of X and

         A2: x2 in the carrier of Y and

         A3: x = [x1, x2] by ZFMISC_1:def 2;

        the InternalRel of X is_reflexive_in the carrier of X by ORDERS_2:def 2;

        then

         A4: [x1, x1] in the InternalRel of X by A1;

        the InternalRel of Y is_reflexive_in the carrier of Y by ORDERS_2:def 2;

        then

         A5: [x2, x2] in the InternalRel of Y by A2;

        set a = [ [x1, x2], [x1, x2]];

        

         A6: (a `1 ) = [x1, x2] & (a `2 ) = [x1, x2];

        ((a `1 ) `1 ) = x1 & ((a `1 ) `2 ) = x2;

        then [x, x] in ["the InternalRel of X, the InternalRel of Y"] by A3, A4, A5, A6, Th10;

        hence thesis by Def2;

      end;

    end

    registration

      let X,Y be antisymmetric RelStr;

      cluster [:X, Y:] -> antisymmetric;

      coherence

      proof

        let x,y be object such that

         A1: x in the carrier of [:X, Y:] and

         A2: y in the carrier of [:X, Y:] and

         A3: [x, y] in the InternalRel of [:X, Y:] and

         A4: [y, x] in the InternalRel of [:X, Y:];

        x in [:the carrier of X, the carrier of Y:] by A1, Def2;

        then

        consider x1,x2 be object such that

         A5: x1 in the carrier of X and

         A6: x2 in the carrier of Y and

         A7: x = [x1, x2] by ZFMISC_1:def 2;

        y in [:the carrier of X, the carrier of Y:] by A2, Def2;

        then

        consider y1,y2 be object such that

         A8: y1 in the carrier of X and

         A9: y2 in the carrier of Y and

         A10: y = [y1, y2] by ZFMISC_1:def 2;

        

         A11: [y, x] in ["the InternalRel of X, the InternalRel of Y"] by A4, Def2;

        then [(( [y, x] `1 ) `1 ), (( [y, x] `2 ) `1 )] in the InternalRel of X by Th10;

        then [(y `1 ), (( [y, x] `2 ) `1 )] in the InternalRel of X;

        then [(y `1 ), (x `1 )] in the InternalRel of X;

        then [y1, ( [x1, x2] `1 )] in the InternalRel of X by A7, A10;

        then

         A12: [y1, x1] in the InternalRel of X;

         [(( [y, x] `1 ) `2 ), (( [y, x] `2 ) `2 )] in the InternalRel of Y by A11, Th10;

        then [(y `2 ), (( [y, x] `2 ) `2 )] in the InternalRel of Y;

        then [(y `2 ), (x `2 )] in the InternalRel of Y;

        then [y2, ( [x1, x2] `2 )] in the InternalRel of Y by A7, A10;

        then

         A13: [y2, x2] in the InternalRel of Y;

        

         A14: [x, y] in ["the InternalRel of X, the InternalRel of Y"] by A3, Def2;

        then [(( [x, y] `1 ) `2 ), (( [x, y] `2 ) `2 )] in the InternalRel of Y by Th10;

        then [(x `2 ), (( [x, y] `2 ) `2 )] in the InternalRel of Y;

        then [(x `2 ), (y `2 )] in the InternalRel of Y;

        then [x2, ( [y1, y2] `2 )] in the InternalRel of Y by A7, A10;

        then

         A15: [x2, y2] in the InternalRel of Y;

         [(( [x, y] `1 ) `1 ), (( [x, y] `2 ) `1 )] in the InternalRel of X by A14, Th10;

        then [(x `1 ), (( [x, y] `2 ) `1 )] in the InternalRel of X;

        then [(x `1 ), (y `1 )] in the InternalRel of X;

        then [x1, ( [y1, y2] `1 )] in the InternalRel of X by A7, A10;

        then [x1, y1] in the InternalRel of X;

        then the InternalRel of Y is_antisymmetric_in the carrier of Y & x1 = y1 by A5, A8, A12, ORDERS_2:def 4, RELAT_2:def 4;

        hence thesis by A6, A7, A9, A10, A15, A13;

      end;

    end

    registration

      let X,Y be transitive RelStr;

      cluster [:X, Y:] -> transitive;

      coherence

      proof

        set P = the InternalRel of X, R = the InternalRel of Y;

        let x,y,z be object such that

         A1: x in the carrier of [:X, Y:] and

         A2: y in the carrier of [:X, Y:] and

         A3: z in the carrier of [:X, Y:] and

         A4: [x, y] in the InternalRel of [:X, Y:] and

         A5: [y, z] in the InternalRel of [:X, Y:];

        y in [:the carrier of X, the carrier of Y:] by A2, Def2;

        then

        consider y1,y2 be object such that

         A6: y1 in the carrier of X and

         A7: y2 in the carrier of Y and

         A8: y = [y1, y2] by ZFMISC_1:def 2;

        z in [:the carrier of X, the carrier of Y:] by A3, Def2;

        then

        consider z1,z2 be object such that

         A9: z1 in the carrier of X and

         A10: z2 in the carrier of Y and

         A11: z = [z1, z2] by ZFMISC_1:def 2;

        

         A12: [y, z] in ["P, R"] by A5, Def2;

        then [(( [y, z] `1 ) `1 ), (( [y, z] `2 ) `1 )] in P by Th10;

        then [(y `1 ), (( [y, z] `2 ) `1 )] in P;

        then [(y `1 ), (z `1 )] in P;

        then [y1, (z `1 )] in P by A8;

        then

         A13: [y1, z1] in P by A11;

        x in [:the carrier of X, the carrier of Y:] by A1, Def2;

        then

        consider x1,x2 be object such that

         A14: x1 in the carrier of X and

         A15: x2 in the carrier of Y and

         A16: x = [x1, x2] by ZFMISC_1:def 2;

        

         A17: [x, y] in ["P, R"] by A4, Def2;

        then [(( [x, y] `1 ) `1 ), (( [x, y] `2 ) `1 )] in P by Th10;

        then [(x `1 ), (( [x, y] `2 ) `1 )] in P;

        then [(x `1 ), (y `1 )] in P;

        then [x1, (y `1 )] in P by A16;

        then P is_transitive_in the carrier of X & [x1, y1] in P by A8, ORDERS_2:def 3;

        then [x1, z1] in P by A14, A6, A9, A13;

        then [x1, (z `1 )] in P by A11;

        then

         A18: [(x `1 ), (z `1 )] in P by A16;

         [(( [y, z] `1 ) `2 ), (( [y, z] `2 ) `2 )] in R by A12, Th10;

        then [(y `2 ), (( [y, z] `2 ) `2 )] in R;

        then [(y `2 ), (z `2 )] in R;

        then [y2, (z `2 )] in R by A8;

        then

         A19: [y2, z2] in R by A11;

         [(( [x, y] `1 ) `2 ), (( [x, y] `2 ) `2 )] in R by A17, Th10;

        then [(x `2 ), (( [x, y] `2 ) `2 )] in R;

        then [(x `2 ), (y `2 )] in R;

        then [x2, (y `2 )] in R by A16;

        then R is_transitive_in the carrier of Y & [x2, y2] in R by A8, ORDERS_2:def 3;

        then [x2, z2] in R by A15, A7, A10, A19;

        then [x2, (z `2 )] in R by A11;

        then

         A20: [(x `2 ), (z `2 )] in R by A16;

        ( [x, z] `1 ) = x & ( [x, z] `2 ) = z;

        then [x, z] in ["P, R"] by A16, A11, A18, A20, Th10;

        hence thesis by Def2;

      end;

    end

    registration

      let X,Y be with_suprema RelStr;

      cluster [:X, Y:] -> with_suprema;

      coherence

      proof

        set IT = [:X, Y:];

        let x,y be Element of IT;

        consider zx be Element of X such that

         A1: (x `1 ) <= zx & (y `1 ) <= zx and

         A2: for z9 be Element of X st (x `1 ) <= z9 & (y `1 ) <= z9 holds zx <= z9 by LATTICE3:def 10;

        consider zy be Element of Y such that

         A3: (x `2 ) <= zy & (y `2 ) <= zy and

         A4: for z9 be Element of Y st (x `2 ) <= z9 & (y `2 ) <= z9 holds zy <= z9 by LATTICE3:def 10;

        

         A5: the carrier of [:X, Y:] = [:the carrier of X, the carrier of Y:] by Def2;

        then

         A6: (ex a,b be object st a in the carrier of X & b in the carrier of Y & x = [a, b]) & ex c,d be object st c in the carrier of X & d in the carrier of Y & y = [c, d] by ZFMISC_1:def 2;

        take z = [zx, zy];

         [(x `1 ), (x `2 )] <= [zx, zy] & [(y `1 ), (y `2 )] <= [zx, zy] by A1, A3, Th11;

        hence x <= z & y <= z by A6;

        let z9 be Element of IT;

        

         A7: ex a,b be object st a in the carrier of X & b in the carrier of Y & z9 = [a, b] by A5, ZFMISC_1:def 2;

        assume

         A8: x <= z9 & y <= z9;

        then (x `2 ) <= (z9 `2 ) & (y `2 ) <= (z9 `2 ) by Th12;

        then

         A9: zy <= (z9 `2 ) by A4;

        (x `1 ) <= (z9 `1 ) & (y `1 ) <= (z9 `1 ) by A8, Th12;

        then zx <= (z9 `1 ) by A2;

        then [zx, zy] <= [(z9 `1 ), (z9 `2 )] by A9, Th11;

        hence thesis by A7;

      end;

    end

    registration

      let X,Y be with_infima RelStr;

      cluster [:X, Y:] -> with_infima;

      coherence

      proof

        set IT = [:X, Y:];

        let x,y be Element of IT;

        consider zx be Element of X such that

         A1: (x `1 ) >= zx & (y `1 ) >= zx and

         A2: for z9 be Element of X st (x `1 ) >= z9 & (y `1 ) >= z9 holds zx >= z9 by LATTICE3:def 11;

        consider zy be Element of Y such that

         A3: (x `2 ) >= zy & (y `2 ) >= zy and

         A4: for z9 be Element of Y st (x `2 ) >= z9 & (y `2 ) >= z9 holds zy >= z9 by LATTICE3:def 11;

        

         A5: the carrier of [:X, Y:] = [:the carrier of X, the carrier of Y:] by Def2;

        then

         A6: (ex a,b be object st a in the carrier of X & b in the carrier of Y & x = [a, b]) & ex c,d be object st c in the carrier of X & d in the carrier of Y & y = [c, d] by ZFMISC_1:def 2;

        take z = [zx, zy];

         [(x `1 ), (x `2 )] >= [zx, zy] & [(y `1 ), (y `2 )] >= [zx, zy] by A1, A3, Th11;

        hence x >= z & y >= z by A6;

        let z9 be Element of IT;

        

         A7: ex a,b be object st a in the carrier of X & b in the carrier of Y & z9 = [a, b] by A5, ZFMISC_1:def 2;

        assume

         A8: x >= z9 & y >= z9;

        then (x `2 ) >= (z9 `2 ) & (y `2 ) >= (z9 `2 ) by Th12;

        then

         A9: zy >= (z9 `2 ) by A4;

        (x `1 ) >= (z9 `1 ) & (y `1 ) >= (z9 `1 ) by A8, Th12;

        then zx >= (z9 `1 ) by A2;

        then [zx, zy] >= [(z9 `1 ), (z9 `2 )] by A9, Th11;

        hence thesis by A7;

      end;

    end

    theorem :: YELLOW_3:14

    for X,Y be RelStr st [:X, Y:] is non empty holds X is non empty & Y is non empty

    proof

      let X,Y be RelStr;

      assume [:X, Y:] is non empty;

      then

       A1: ex x be object st x in the carrier of [:X, Y:] by XBOOLE_0:def 1;

      the carrier of [:X, Y:] = [:the carrier of X, the carrier of Y:] by Def2;

      hence thesis by A1, MCART_1: 10;

    end;

    theorem :: YELLOW_3:15

    for X,Y be non empty RelStr st [:X, Y:] is reflexive holds X is reflexive & Y is reflexive

    proof

      let X,Y be non empty RelStr such that

       A1: [:X, Y:] is reflexive;

      for x be Element of X holds x <= x

      proof

        set y = the Element of Y;

        let x be Element of X;

         [x, y] <= [x, y] by A1, YELLOW_0:def 1;

        hence thesis by Th11;

      end;

      hence X is reflexive by YELLOW_0:def 1;

      for y be Element of Y holds y <= y

      proof

        set x = the Element of X;

        let y be Element of Y;

         [x, y] <= [x, y] by A1, YELLOW_0:def 1;

        hence thesis by Th11;

      end;

      hence thesis by YELLOW_0:def 1;

    end;

    theorem :: YELLOW_3:16

    for X,Y be non empty reflexive RelStr st [:X, Y:] is antisymmetric holds X is antisymmetric & Y is antisymmetric

    proof

      let X,Y be non empty reflexive RelStr such that

       A1: [:X, Y:] is antisymmetric;

      for x,y be Element of X st x <= y & y <= x holds x = y

      proof

        set z = the Element of Y;

        

         A2: z <= z;

        let x,y be Element of X;

        assume x <= y & y <= x;

        then [x, z] <= [y, z] & [y, z] <= [x, z] by A2, Th11;

        then [x, z] = [y, z] by A1, YELLOW_0:def 3;

        hence thesis by XTUPLE_0: 1;

      end;

      hence X is antisymmetric by YELLOW_0:def 3;

      for x,y be Element of Y st x <= y & y <= x holds x = y

      proof

        set z = the Element of X;

        

         A3: z <= z;

        let x,y be Element of Y;

        assume x <= y & y <= x;

        then [z, x] <= [z, y] & [z, y] <= [z, x] by A3, Th11;

        then [z, x] = [z, y] by A1, YELLOW_0:def 3;

        hence thesis by XTUPLE_0: 1;

      end;

      hence thesis by YELLOW_0:def 3;

    end;

    theorem :: YELLOW_3:17

    for X,Y be non empty reflexive RelStr st [:X, Y:] is transitive holds X is transitive & Y is transitive

    proof

      let X,Y be non empty reflexive RelStr such that

       A1: [:X, Y:] is transitive;

      for x,y,z be Element of X st x <= y & y <= z holds x <= z

      proof

        set a = the Element of Y;

        

         A2: a <= a;

        let x,y,z be Element of X;

        assume x <= y & y <= z;

        then [x, a] <= [y, a] & [y, a] <= [z, a] by A2, Th11;

        then [x, a] <= [z, a] by A1, YELLOW_0:def 2;

        hence thesis by Th11;

      end;

      hence X is transitive by YELLOW_0:def 2;

      for x,y,z be Element of Y st x <= y & y <= z holds x <= z

      proof

        set a = the Element of X;

        

         A3: a <= a;

        let x,y,z be Element of Y;

        assume x <= y & y <= z;

        then [a, x] <= [a, y] & [a, y] <= [a, z] by A3, Th11;

        then [a, x] <= [a, z] by A1, YELLOW_0:def 2;

        hence thesis by Th11;

      end;

      hence thesis by YELLOW_0:def 2;

    end;

    theorem :: YELLOW_3:18

    for X,Y be non empty reflexive RelStr st [:X, Y:] is with_suprema holds X is with_suprema & Y is with_suprema

    proof

      let X,Y be non empty reflexive RelStr such that

       A1: [:X, Y:] is with_suprema;

      

       A2: the carrier of [:X, Y:] = [:the carrier of X, the carrier of Y:] by Def2;

      thus X is with_suprema

      proof

        let x,y be Element of X;

        set a = the Element of Y;

        

         A3: a <= a;

        consider z be Element of [:X, Y:] such that

         A4: [x, a] <= z & [y, a] <= z and

         A5: for z9 be Element of [:X, Y:] st [x, a] <= z9 & [y, a] <= z9 holds z <= z9 by A1;

        take (z `1 );

        

         A6: z = [(z `1 ), (z `2 )] by A2, MCART_1: 21;

        hence x <= (z `1 ) & y <= (z `1 ) by A4, Th11;

        let z9 be Element of X;

        assume x <= z9 & y <= z9;

        then [x, a] <= [z9, a] & [y, a] <= [z9, a] by A3, Th11;

        then z <= [z9, a] by A5;

        hence (z `1 ) <= z9 by A6, Th11;

      end;

      set a = the Element of X;

      

       A7: a <= a;

      let x,y be Element of Y;

      consider z be Element of [:X, Y:] such that

       A8: [a, x] <= z & [a, y] <= z and

       A9: for z9 be Element of [:X, Y:] st [a, x] <= z9 & [a, y] <= z9 holds z <= z9 by A1;

      take (z `2 );

      

       A10: z = [(z `1 ), (z `2 )] by A2, MCART_1: 21;

      hence x <= (z `2 ) & y <= (z `2 ) by A8, Th11;

      let z9 be Element of Y;

      assume x <= z9 & y <= z9;

      then [a, x] <= [a, z9] & [a, y] <= [a, z9] by A7, Th11;

      then z <= [a, z9] by A9;

      hence (z `2 ) <= z9 by A10, Th11;

    end;

    theorem :: YELLOW_3:19

    for X,Y be non empty reflexive RelStr st [:X, Y:] is with_infima holds X is with_infima & Y is with_infima

    proof

      let X,Y be non empty reflexive RelStr such that

       A1: [:X, Y:] is with_infima;

      

       A2: the carrier of [:X, Y:] = [:the carrier of X, the carrier of Y:] by Def2;

      thus X is with_infima

      proof

        let x,y be Element of X;

        set a = the Element of Y;

        

         A3: a <= a;

        consider z be Element of [:X, Y:] such that

         A4: [x, a] >= z & [y, a] >= z and

         A5: for z9 be Element of [:X, Y:] st [x, a] >= z9 & [y, a] >= z9 holds z >= z9 by A1;

        take (z `1 );

        

         A6: z = [(z `1 ), (z `2 )] by A2, MCART_1: 21;

        hence x >= (z `1 ) & y >= (z `1 ) by A4, Th11;

        let z9 be Element of X;

        assume x >= z9 & y >= z9;

        then [x, a] >= [z9, a] & [y, a] >= [z9, a] by A3, Th11;

        then z >= [z9, a] by A5;

        hence thesis by A6, Th11;

      end;

      set a = the Element of X;

      

       A7: a <= a;

      let x,y be Element of Y;

      consider z be Element of [:X, Y:] such that

       A8: [a, x] >= z & [a, y] >= z and

       A9: for z9 be Element of [:X, Y:] st [a, x] >= z9 & [a, y] >= z9 holds z >= z9 by A1;

      take (z `2 );

      

       A10: z = [(z `1 ), (z `2 )] by A2, MCART_1: 21;

      hence x >= (z `2 ) & y >= (z `2 ) by A8, Th11;

      let z9 be Element of Y;

      assume x >= z9 & y >= z9;

      then [a, x] >= [a, z9] & [a, y] >= [a, z9] by A7, Th11;

      then z >= [a, z9] by A9;

      hence thesis by A10, Th11;

    end;

    registration

      let S1,S2 be RelStr;

      let D1 be directed Subset of S1, D2 be directed Subset of S2;

      cluster [:D1, D2:] -> directed;

      coherence

      proof

        set X = [:D1, D2:];

        X is directed

        proof

          let x,y be Element of [:S1, S2:];

          assume that

           A1: x in X and

           A2: y in X;

          consider x1,x2 be object such that

           A3: x1 in D1 and

           A4: x2 in D2 and

           A5: x = [x1, x2] by A1, ZFMISC_1:def 2;

          reconsider S29 = S2 as non empty RelStr by A4;

          reconsider S19 = S1 as non empty RelStr by A3;

          consider y1,y2 be object such that

           A6: y1 in D1 and

           A7: y2 in D2 and

           A8: y = [y1, y2] by A2, ZFMISC_1:def 2;

          reconsider x2, y2 as Element of S2 by A4, A7;

          consider xy2 be Element of S2 such that

           A9: xy2 in D2 and

           A10: x2 <= xy2 & y2 <= xy2 by A4, A7, WAYBEL_0:def 1;

          reconsider x1, y1 as Element of S1 by A3, A6;

          consider xy1 be Element of S1 such that

           A11: xy1 in D1 and

           A12: x1 <= xy1 & y1 <= xy1 by A3, A6, WAYBEL_0:def 1;

          reconsider xy29 = xy2 as Element of S29;

          reconsider xy19 = xy1 as Element of S19;

           [xy19, xy29] is Element of [:S19, S29:];

          then

          reconsider z = [xy1, xy2] as Element of [:S1, S2:];

          take z;

          thus z in X by A11, A9, ZFMISC_1: 87;

          S1 is non empty & S2 is non empty by A3, A4;

          hence thesis by A5, A8, A12, A10, Th11;

        end;

        hence thesis;

      end;

    end

    theorem :: YELLOW_3:20

    for S1,S2 be non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 st [:D1, D2:] is directed holds D1 is directed & D2 is directed

    proof

      let S1,S2 be non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2 such that

       A1: [:D1, D2:] is directed;

      thus D1 is directed

      proof

        set q1 = the Element of D2;

        let x,y be Element of S1;

        assume x in D1 & y in D1;

        then [x, q1] in [:D1, D2:] & [y, q1] in [:D1, D2:] by ZFMISC_1: 87;

        then

        consider z be Element of [:S1, S2:] such that

         A2: z in [:D1, D2:] and

         A3: [x, q1] <= z & [y, q1] <= z by A1;

        reconsider z2 = (z `2 ) as Element of D2 by A2, MCART_1: 10;

        reconsider zz = (z `1 ) as Element of D1 by A2, MCART_1: 10;

        take zz;

        thus zz in D1;

        ex x,y be object st x in D1 & y in D2 & z = [x, y] by A2, ZFMISC_1:def 2;

        then [x, q1] <= [zz, z2] & [y, q1] <= [zz, z2] by A3;

        hence thesis by Th11;

      end;

      set q1 = the Element of D1;

      let x,y be Element of S2;

      assume x in D2 & y in D2;

      then [q1, x] in [:D1, D2:] & [q1, y] in [:D1, D2:] by ZFMISC_1: 87;

      then

      consider z be Element of [:S1, S2:] such that

       A4: z in [:D1, D2:] and

       A5: [q1, x] <= z & [q1, y] <= z by A1;

      reconsider z2 = (z `1 ) as Element of D1 by A4, MCART_1: 10;

      reconsider zz = (z `2 ) as Element of D2 by A4, MCART_1: 10;

      take zz;

      thus zz in D2;

      ex x,y be object st x in D1 & y in D2 & z = [x, y] by A4, ZFMISC_1:def 2;

      then [q1, x] <= [z2, zz] & [q1, y] <= [z2, zz] by A5;

      hence thesis by Th11;

    end;

    theorem :: YELLOW_3:21

    

     Th21: for S1,S2 be non empty RelStr holds for D be non empty Subset of [:S1, S2:] holds ( proj1 D) is non empty & ( proj2 D) is non empty

    proof

      let S1,S2 be non empty RelStr, D be non empty Subset of [:S1, S2:];

      reconsider D1 = D as non empty Subset of [:the carrier of S1, the carrier of S2:] by Def2;

      ( proj1 D1) is non empty;

      hence thesis;

    end;

    theorem :: YELLOW_3:22

    for S1,S2 be non empty reflexive RelStr holds for D be non empty directed Subset of [:S1, S2:] holds ( proj1 D) is directed & ( proj2 D) is directed

    proof

      let S1,S2 be non empty reflexive RelStr, D be non empty directed Subset of [:S1, S2:];

      set D1 = ( proj1 D), D2 = ( proj2 D);

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A1: D c= [:( proj1 D), ( proj2 D):] by Th1;

      thus D1 is directed

      proof

        let x,y be Element of S1;

        assume that

         A2: x in D1 and

         A3: y in D1;

        consider q2 be object such that

         A4: [y, q2] in D by A3, XTUPLE_0:def 12;

        reconsider D29 = D2 as non empty Subset of S2 by A2, FUNCT_5: 16;

        reconsider D19 = D1 as non empty Subset of S1 by A2;

        consider q1 be object such that

         A5: [x, q1] in D by A2, XTUPLE_0:def 12;

        reconsider q2 as Element of D29 by A4, XTUPLE_0:def 13;

        reconsider q1 as Element of D29 by A5, XTUPLE_0:def 13;

        consider z be Element of [:S1, S2:] such that

         A6: z in D and

         A7: [x, q1] <= z & [y, q2] <= z by A5, A4, WAYBEL_0:def 1;

        reconsider z2 = (z `2 ) as Element of D29 by A1, A6, MCART_1: 10;

        reconsider zz = (z `1 ) as Element of D19 by A1, A6, MCART_1: 10;

        take zz;

        thus zz in D1;

        ex x,y be object st x in D19 & y in D29 & z = [x, y] by A1, A6, ZFMISC_1:def 2;

        then z = [zz, z2];

        hence x <= zz & y <= zz by A7, Th11;

      end;

      let x,y be Element of S2;

      assume that

       A8: x in D2 and

       A9: y in D2;

      consider q2 be object such that

       A10: [q2, y] in D by A9, XTUPLE_0:def 13;

      reconsider D29 = D2 as non empty Subset of S2 by A8;

      reconsider D19 = D1 as non empty Subset of S1 by A8, FUNCT_5: 16;

      consider q1 be object such that

       A11: [q1, x] in D by A8, XTUPLE_0:def 13;

      reconsider q2 as Element of D19 by A10, XTUPLE_0:def 12;

      reconsider q1 as Element of D19 by A11, XTUPLE_0:def 12;

      consider z be Element of [:S1, S2:] such that

       A12: z in D and

       A13: [q1, x] <= z & [q2, y] <= z by A11, A10, WAYBEL_0:def 1;

      reconsider z2 = (z `1 ) as Element of D19 by A1, A12, MCART_1: 10;

      reconsider zz = (z `2 ) as Element of D29 by A1, A12, MCART_1: 10;

      take zz;

      thus zz in D2;

      ex x,y be object st x in D19 & y in D29 & z = [x, y] by A1, A12, ZFMISC_1:def 2;

      then z = [z2, zz];

      hence x <= zz & y <= zz by A13, Th11;

    end;

    registration

      let S1,S2 be RelStr;

      let D1 be filtered Subset of S1, D2 be filtered Subset of S2;

      cluster [:D1, D2:] -> filtered;

      coherence

      proof

        set X = [:D1, D2:];

        X is filtered

        proof

          let x,y be Element of [:S1, S2:];

          assume that

           A1: x in X and

           A2: y in X;

          consider x1,x2 be object such that

           A3: x1 in D1 and

           A4: x2 in D2 and

           A5: x = [x1, x2] by A1, ZFMISC_1:def 2;

          reconsider S29 = S2 as non empty RelStr by A4;

          reconsider S19 = S1 as non empty RelStr by A3;

          consider y1,y2 be object such that

           A6: y1 in D1 and

           A7: y2 in D2 and

           A8: y = [y1, y2] by A2, ZFMISC_1:def 2;

          reconsider x2, y2 as Element of S2 by A4, A7;

          consider xy2 be Element of S2 such that

           A9: xy2 in D2 and

           A10: x2 >= xy2 & y2 >= xy2 by A4, A7, WAYBEL_0:def 2;

          reconsider x1, y1 as Element of S1 by A3, A6;

          consider xy1 be Element of S1 such that

           A11: xy1 in D1 and

           A12: x1 >= xy1 & y1 >= xy1 by A3, A6, WAYBEL_0:def 2;

          reconsider xy29 = xy2 as Element of S29;

          reconsider xy19 = xy1 as Element of S19;

           [xy19, xy29] is Element of [:S19, S29:];

          then

          reconsider z = [xy1, xy2] as Element of [:S1, S2:];

          take z;

          thus z in X by A11, A9, ZFMISC_1: 87;

          S1 is non empty & S2 is non empty by A3, A4;

          hence thesis by A5, A8, A12, A10, Th11;

        end;

        hence thesis;

      end;

    end

    theorem :: YELLOW_3:23

    for S1,S2 be non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 st [:D1, D2:] is filtered holds D1 is filtered & D2 is filtered

    proof

      let S1,S2 be non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2 such that

       A1: [:D1, D2:] is filtered;

      thus D1 is filtered

      proof

        set q1 = the Element of D2;

        let x,y be Element of S1;

        assume x in D1 & y in D1;

        then [x, q1] in [:D1, D2:] & [y, q1] in [:D1, D2:] by ZFMISC_1: 87;

        then

        consider z be Element of [:S1, S2:] such that

         A2: z in [:D1, D2:] and

         A3: [x, q1] >= z & [y, q1] >= z by A1;

        reconsider z2 = (z `2 ) as Element of D2 by A2, MCART_1: 10;

        reconsider zz = (z `1 ) as Element of D1 by A2, MCART_1: 10;

        take zz;

        thus zz in D1;

        ex x,y be object st x in D1 & y in D2 & z = [x, y] by A2, ZFMISC_1:def 2;

        then [x, q1] >= [zz, z2] & [y, q1] >= [zz, z2] by A3;

        hence thesis by Th11;

      end;

      set q1 = the Element of D1;

      let x,y be Element of S2;

      assume x in D2 & y in D2;

      then [q1, x] in [:D1, D2:] & [q1, y] in [:D1, D2:] by ZFMISC_1: 87;

      then

      consider z be Element of [:S1, S2:] such that

       A4: z in [:D1, D2:] and

       A5: [q1, x] >= z & [q1, y] >= z by A1;

      reconsider z2 = (z `1 ) as Element of D1 by A4, MCART_1: 10;

      reconsider zz = (z `2 ) as Element of D2 by A4, MCART_1: 10;

      take zz;

      thus zz in D2;

      ex x,y be object st x in D1 & y in D2 & z = [x, y] by A4, ZFMISC_1:def 2;

      then [q1, x] >= [z2, zz] & [q1, y] >= [z2, zz] by A5;

      hence thesis by Th11;

    end;

    theorem :: YELLOW_3:24

    for S1,S2 be non empty reflexive RelStr holds for D be non empty filtered Subset of [:S1, S2:] holds ( proj1 D) is filtered & ( proj2 D) is filtered

    proof

      let S1,S2 be non empty reflexive RelStr, D be non empty filtered Subset of [:S1, S2:];

      set D1 = ( proj1 D), D2 = ( proj2 D);

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A1: D c= [:( proj1 D), ( proj2 D):] by Th1;

      thus D1 is filtered

      proof

        let x,y be Element of S1;

        assume that

         A2: x in D1 and

         A3: y in D1;

        consider q2 be object such that

         A4: [y, q2] in D by A3, XTUPLE_0:def 12;

        reconsider D29 = D2 as non empty Subset of S2 by A2, FUNCT_5: 16;

        reconsider D19 = D1 as non empty Subset of S1 by A2;

        consider q1 be object such that

         A5: [x, q1] in D by A2, XTUPLE_0:def 12;

        reconsider q2 as Element of D29 by A4, XTUPLE_0:def 13;

        reconsider q1 as Element of D29 by A5, XTUPLE_0:def 13;

        consider z be Element of [:S1, S2:] such that

         A6: z in D and

         A7: [x, q1] >= z & [y, q2] >= z by A5, A4, WAYBEL_0:def 2;

        reconsider z2 = (z `2 ) as Element of D29 by A1, A6, MCART_1: 10;

        reconsider zz = (z `1 ) as Element of D19 by A1, A6, MCART_1: 10;

        take zz;

        thus zz in D1;

        ex x,y be object st x in D19 & y in D29 & z = [x, y] by A1, A6, ZFMISC_1:def 2;

        then z = [zz, z2];

        hence thesis by A7, Th11;

      end;

      let x,y be Element of S2;

      assume that

       A8: x in D2 and

       A9: y in D2;

      consider q2 be object such that

       A10: [q2, y] in D by A9, XTUPLE_0:def 13;

      reconsider D29 = D2 as non empty Subset of S2 by A8;

      reconsider D19 = D1 as non empty Subset of S1 by A8, FUNCT_5: 16;

      consider q1 be object such that

       A11: [q1, x] in D by A8, XTUPLE_0:def 13;

      reconsider q2 as Element of D19 by A10, XTUPLE_0:def 12;

      reconsider q1 as Element of D19 by A11, XTUPLE_0:def 12;

      consider z be Element of [:S1, S2:] such that

       A12: z in D and

       A13: [q1, x] >= z & [q2, y] >= z by A11, A10, WAYBEL_0:def 2;

      reconsider z2 = (z `1 ) as Element of D19 by A1, A12, MCART_1: 10;

      reconsider zz = (z `2 ) as Element of D29 by A1, A12, MCART_1: 10;

      take zz;

      thus zz in D2;

      ex x,y be object st x in D19 & y in D29 & z = [x, y] by A1, A12, ZFMISC_1:def 2;

      then z = [z2, zz];

      hence thesis by A13, Th11;

    end;

    registration

      let S1,S2 be RelStr, D1 be upper Subset of S1, D2 be upper Subset of S2;

      cluster [:D1, D2:] -> upper;

      coherence

      proof

        set X = [:D1, D2:];

        X is upper

        proof

          let x,y be Element of [:S1, S2:];

          assume that

           A1: x in X and

           A2: x <= y;

          consider x1,x2 be object such that

           A3: x1 in D1 and

           A4: x2 in D2 and

           A5: x = [x1, x2] by A1, ZFMISC_1:def 2;

          reconsider s1 = S1, s2 = S2 as non empty RelStr by A3, A4;

          set C1 = the carrier of s1, C2 = the carrier of s2;

          the carrier of [:S1, S2:] = [:C1, C2:] by Def2;

          then

          consider y1,y2 be object such that

           A6: y1 in C1 and

           A7: y2 in C2 and

           A8: y = [y1, y2] by ZFMISC_1:def 2;

          reconsider x2, y2 as Element of s2 by A4, A7;

          x2 <= y2 by A2, A3, A5, A6, A8, Th11;

          then

           A9: y2 in D2 by A4, WAYBEL_0:def 20;

          reconsider x1, y1 as Element of s1 by A3, A6;

          x1 <= y1 by A2, A4, A5, A7, A8, Th11;

          then y1 in D1 by A3, WAYBEL_0:def 20;

          hence thesis by A8, A9, ZFMISC_1: 87;

        end;

        hence thesis;

      end;

    end

    theorem :: YELLOW_3:25

    for S1,S2 be non empty reflexive RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 st [:D1, D2:] is upper holds D1 is upper & D2 is upper

    proof

      let S1,S2 be non empty reflexive RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2 such that

       A1: [:D1, D2:] is upper;

      thus D1 is upper

      proof

        set q1 = the Element of D2;

        let x,y be Element of S1;

        assume that

         A2: x in D1 and

         A3: x <= y;

        

         A4: [x, q1] in [:D1, D2:] by A2, ZFMISC_1: 87;

        q1 <= q1;

        then [x, q1] <= [y, q1] by A3, Th11;

        then [y, q1] in [:D1, D2:] by A1, A4;

        hence thesis by ZFMISC_1: 87;

      end;

      set q1 = the Element of D1;

      let x,y be Element of S2;

      assume that

       A5: x in D2 and

       A6: x <= y;

      

       A7: [q1, x] in [:D1, D2:] by A5, ZFMISC_1: 87;

      q1 <= q1;

      then [q1, x] <= [q1, y] by A6, Th11;

      then [q1, y] in [:D1, D2:] by A1, A7;

      hence thesis by ZFMISC_1: 87;

    end;

    theorem :: YELLOW_3:26

    for S1,S2 be non empty reflexive RelStr holds for D be non empty upper Subset of [:S1, S2:] holds ( proj1 D) is upper & ( proj2 D) is upper

    proof

      let S1,S2 be non empty reflexive RelStr, D be non empty upper Subset of [:S1, S2:];

      set D1 = ( proj1 D), D2 = ( proj2 D);

      reconsider d1 = D1 as non empty Subset of S1 by Th21;

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A1: D c= [:D1, D2:] by Th1;

      thus D1 is upper

      proof

        reconsider d2 = D2 as non empty Subset of S2 by Th21;

        let x,y be Element of S1 such that

         A2: x in D1 and

         A3: x <= y;

        consider q1 be object such that

         A4: [x, q1] in D by A2, XTUPLE_0:def 12;

        reconsider q1 as Element of d2 by A1, A4, ZFMISC_1: 87;

        q1 <= q1;

        then [x, q1] <= [y, q1] by A3, Th11;

        then [y, q1] in D by A4, WAYBEL_0:def 20;

        hence thesis by A1, ZFMISC_1: 87;

      end;

      let x,y be Element of S2 such that

       A5: x in D2 and

       A6: x <= y;

      consider q1 be object such that

       A7: [q1, x] in D by A5, XTUPLE_0:def 13;

      reconsider q1 as Element of d1 by A1, A7, ZFMISC_1: 87;

      q1 <= q1;

      then [q1, x] <= [q1, y] by A6, Th11;

      then [q1, y] in D by A7, WAYBEL_0:def 20;

      hence thesis by A1, ZFMISC_1: 87;

    end;

    registration

      let S1,S2 be RelStr, D1 be lower Subset of S1, D2 be lower Subset of S2;

      cluster [:D1, D2:] -> lower;

      coherence

      proof

        set X = [:D1, D2:];

        X is lower

        proof

          let x,y be Element of [:S1, S2:];

          assume that

           A1: x in X and

           A2: x >= y;

          consider x1,x2 be object such that

           A3: x1 in D1 and

           A4: x2 in D2 and

           A5: x = [x1, x2] by A1, ZFMISC_1:def 2;

          reconsider s1 = S1, s2 = S2 as non empty RelStr by A3, A4;

          set C1 = the carrier of s1, C2 = the carrier of s2;

          the carrier of [:S1, S2:] = [:C1, C2:] by Def2;

          then

          consider y1,y2 be object such that

           A6: y1 in C1 and

           A7: y2 in C2 and

           A8: y = [y1, y2] by ZFMISC_1:def 2;

          reconsider x2, y2 as Element of s2 by A4, A7;

          x2 >= y2 by A2, A3, A5, A6, A8, Th11;

          then

           A9: y2 in D2 by A4, WAYBEL_0:def 19;

          reconsider x1, y1 as Element of s1 by A3, A6;

          x1 >= y1 by A2, A4, A5, A7, A8, Th11;

          then y1 in D1 by A3, WAYBEL_0:def 19;

          hence thesis by A8, A9, ZFMISC_1: 87;

        end;

        hence thesis;

      end;

    end

    theorem :: YELLOW_3:27

    for S1,S2 be non empty reflexive RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 st [:D1, D2:] is lower holds D1 is lower & D2 is lower

    proof

      let S1,S2 be non empty reflexive RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2 such that

       A1: [:D1, D2:] is lower;

      thus D1 is lower

      proof

        set q1 = the Element of D2;

        let x,y be Element of S1;

        assume that

         A2: x in D1 and

         A3: x >= y;

        

         A4: [x, q1] in [:D1, D2:] by A2, ZFMISC_1: 87;

        q1 <= q1;

        then [x, q1] >= [y, q1] by A3, Th11;

        then [y, q1] in [:D1, D2:] by A1, A4;

        hence thesis by ZFMISC_1: 87;

      end;

      set q1 = the Element of D1;

      let x,y be Element of S2;

      assume that

       A5: x in D2 and

       A6: x >= y;

      

       A7: [q1, x] in [:D1, D2:] by A5, ZFMISC_1: 87;

      q1 <= q1;

      then [q1, x] >= [q1, y] by A6, Th11;

      then [q1, y] in [:D1, D2:] by A1, A7;

      hence thesis by ZFMISC_1: 87;

    end;

    theorem :: YELLOW_3:28

    for S1,S2 be non empty reflexive RelStr holds for D be non empty lower Subset of [:S1, S2:] holds ( proj1 D) is lower & ( proj2 D) is lower

    proof

      let S1,S2 be non empty reflexive RelStr, D be non empty lower Subset of [:S1, S2:];

      set D1 = ( proj1 D), D2 = ( proj2 D);

      reconsider d1 = D1 as non empty Subset of S1 by Th21;

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A1: D c= [:D1, D2:] by Th1;

      thus D1 is lower

      proof

        reconsider d2 = D2 as non empty Subset of S2 by Th21;

        let x,y be Element of S1 such that

         A2: x in D1 and

         A3: x >= y;

        consider q1 be object such that

         A4: [x, q1] in D by A2, XTUPLE_0:def 12;

        reconsider q1 as Element of d2 by A1, A4, ZFMISC_1: 87;

        q1 <= q1;

        then [x, q1] >= [y, q1] by A3, Th11;

        then [y, q1] in D by A4, WAYBEL_0:def 19;

        hence thesis by A1, ZFMISC_1: 87;

      end;

      let x,y be Element of S2 such that

       A5: x in D2 and

       A6: x >= y;

      consider q1 be object such that

       A7: [q1, x] in D by A5, XTUPLE_0:def 13;

      reconsider q1 as Element of d1 by A1, A7, ZFMISC_1: 87;

      q1 <= q1;

      then [q1, x] >= [q1, y] by A6, Th11;

      then [q1, y] in D by A7, WAYBEL_0:def 19;

      hence thesis by A1, ZFMISC_1: 87;

    end;

    definition

      let R be RelStr;

      :: YELLOW_3:def3

      attr R is void means

      : Def3: the InternalRel of R is empty;

    end

    registration

      cluster empty -> void for RelStr;

      coherence ;

    end

    registration

      cluster non void non empty strict for Poset;

      existence

      proof

        set R = the non empty strict Poset;

        take R;

        (ex x be object st x in the carrier of R) & the InternalRel of R is_reflexive_in the carrier of R by ORDERS_2:def 2, XBOOLE_0:def 1;

        hence the InternalRel of R is non empty;

        thus thesis;

      end;

    end

    registration

      cluster non void -> non empty for RelStr;

      coherence ;

    end

    registration

      cluster non empty reflexive -> non void for RelStr;

      coherence

      proof

        let R be RelStr;

        assume R is non empty reflexive;

        then

        reconsider R1 = R as non empty reflexive RelStr;

        (ex x be object st x in the carrier of R1) & the InternalRel of R1 is_reflexive_in the carrier of R1 by ORDERS_2:def 2, XBOOLE_0:def 1;

        hence the InternalRel of R is non empty;

      end;

    end

    registration

      let R be non void RelStr;

      cluster the InternalRel of R -> non empty;

      coherence by Def3;

    end

    theorem :: YELLOW_3:29

    

     Th29: for S1,S2 be non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 holds for x be Element of S1, y be Element of S2 st [x, y] is_>=_than [:D1, D2:] holds x is_>=_than D1 & y is_>=_than D2

    proof

      let S1,S2 be non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: [x, y] is_>=_than [:D1, D2:];

      thus x is_>=_than D1

      proof

        set a = the Element of D2;

        let b be Element of S1;

        assume b in D1;

        then [b, a] in [:D1, D2:] by ZFMISC_1: 87;

        then [b, a] <= [x, y] by A1;

        hence thesis by Th11;

      end;

      set b = the Element of D1;

      let a be Element of S2;

      assume a in D2;

      then [b, a] in [:D1, D2:] by ZFMISC_1: 87;

      then [b, a] <= [x, y] by A1;

      hence thesis by Th11;

    end;

    theorem :: YELLOW_3:30

    

     Th30: for S1,S2 be non empty RelStr holds for D1 be Subset of S1, D2 be Subset of S2 holds for x be Element of S1, y be Element of S2 st x is_>=_than D1 & y is_>=_than D2 holds [x, y] is_>=_than [:D1, D2:]

    proof

      let S1,S2 be non empty RelStr, D1 be Subset of S1, D2 be Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: x is_>=_than D1 & y is_>=_than D2;

      let b be Element of [:S1, S2:];

      assume b in [:D1, D2:];

      then

      consider b1,b2 be object such that

       A2: b1 in D1 and

       A3: b2 in D2 and

       A4: b = [b1, b2] by ZFMISC_1:def 2;

      reconsider b2 as Element of S2 by A3;

      reconsider b1 as Element of S1 by A2;

      b1 <= x & b2 <= y by A1, A2, A3;

      hence thesis by A4, Th11;

    end;

    theorem :: YELLOW_3:31

    

     Th31: for S1,S2 be non empty RelStr holds for D be Subset of [:S1, S2:] holds for x be Element of S1, y be Element of S2 holds [x, y] is_>=_than D iff x is_>=_than ( proj1 D) & y is_>=_than ( proj2 D)

    proof

      let S1,S2 be non empty RelStr, D be Subset of [:S1, S2:], x be Element of S1, y be Element of S2;

      set D1 = ( proj1 D), D2 = ( proj2 D);

      hereby

        assume

         A1: [x, y] is_>=_than D;

        thus x is_>=_than D1

        proof

          let q be Element of S1;

          assume q in D1;

          then

          consider z be object such that

           A2: [q, z] in D by XTUPLE_0:def 12;

          reconsider d2 = D2 as non empty Subset of S2 by A2, XTUPLE_0:def 13;

          reconsider z as Element of d2 by A2, XTUPLE_0:def 13;

           [x, y] >= [q, z] by A1, A2;

          hence thesis by Th11;

        end;

        thus y is_>=_than D2

        proof

          let q be Element of S2;

          assume q in D2;

          then

          consider z be object such that

           A3: [z, q] in D by XTUPLE_0:def 13;

          reconsider d1 = D1 as non empty Subset of S1 by A3, XTUPLE_0:def 12;

          reconsider z as Element of d1 by A3, XTUPLE_0:def 12;

           [x, y] >= [z, q] by A1, A3;

          hence thesis by Th11;

        end;

      end;

      assume x is_>=_than ( proj1 D) & y is_>=_than ( proj2 D);

      then

       A4: [x, y] is_>=_than [:D1, D2:] by Th30;

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then D c= [:D1, D2:] by Th1;

      hence thesis by A4;

    end;

    theorem :: YELLOW_3:32

    

     Th32: for S1,S2 be non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 holds for x be Element of S1, y be Element of S2 st [x, y] is_<=_than [:D1, D2:] holds x is_<=_than D1 & y is_<=_than D2

    proof

      let S1,S2 be non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: [x, y] is_<=_than [:D1, D2:];

      thus x is_<=_than D1

      proof

        set a = the Element of D2;

        let b be Element of S1;

        assume b in D1;

        then [b, a] in [:D1, D2:] by ZFMISC_1: 87;

        then [b, a] >= [x, y] by A1;

        hence thesis by Th11;

      end;

      set b = the Element of D1;

      let a be Element of S2;

      assume a in D2;

      then [b, a] in [:D1, D2:] by ZFMISC_1: 87;

      then [b, a] >= [x, y] by A1;

      hence thesis by Th11;

    end;

    theorem :: YELLOW_3:33

    

     Th33: for S1,S2 be non empty RelStr holds for D1 be Subset of S1, D2 be Subset of S2 holds for x be Element of S1, y be Element of S2 st x is_<=_than D1 & y is_<=_than D2 holds [x, y] is_<=_than [:D1, D2:]

    proof

      let S1,S2 be non empty RelStr, D1 be Subset of S1, D2 be Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: x is_<=_than D1 & y is_<=_than D2;

      let b be Element of [:S1, S2:];

      assume b in [:D1, D2:];

      then

      consider b1,b2 be object such that

       A2: b1 in D1 and

       A3: b2 in D2 and

       A4: b = [b1, b2] by ZFMISC_1:def 2;

      reconsider b2 as Element of S2 by A3;

      reconsider b1 as Element of S1 by A2;

      b1 >= x & b2 >= y by A1, A2, A3;

      hence thesis by A4, Th11;

    end;

    theorem :: YELLOW_3:34

    

     Th34: for S1,S2 be non empty RelStr holds for D be Subset of [:S1, S2:] holds for x be Element of S1, y be Element of S2 holds [x, y] is_<=_than D iff x is_<=_than ( proj1 D) & y is_<=_than ( proj2 D)

    proof

      let S1,S2 be non empty RelStr, D be Subset of [:S1, S2:], x be Element of S1, y be Element of S2;

      set D1 = ( proj1 D), D2 = ( proj2 D);

      hereby

        assume

         A1: [x, y] is_<=_than D;

        thus x is_<=_than D1

        proof

          let q be Element of S1;

          assume q in D1;

          then

          consider z be object such that

           A2: [q, z] in D by XTUPLE_0:def 12;

          reconsider d2 = D2 as non empty Subset of S2 by A2, XTUPLE_0:def 13;

          reconsider z as Element of d2 by A2, XTUPLE_0:def 13;

           [x, y] <= [q, z] by A1, A2;

          hence thesis by Th11;

        end;

        thus y is_<=_than D2

        proof

          let q be Element of S2;

          assume q in D2;

          then

          consider z be object such that

           A3: [z, q] in D by XTUPLE_0:def 13;

          reconsider d1 = D1 as non empty Subset of S1 by A3, XTUPLE_0:def 12;

          reconsider z as Element of d1 by A3, XTUPLE_0:def 12;

           [x, y] <= [z, q] by A1, A3;

          hence thesis by Th11;

        end;

      end;

      assume x is_<=_than ( proj1 D) & y is_<=_than ( proj2 D);

      then

       A4: [x, y] is_<=_than [:D1, D2:] by Th33;

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then D c= [:D1, D2:] by Th1;

      hence thesis by A4;

    end;

    theorem :: YELLOW_3:35

    

     Th35: for S1,S2 be antisymmetric non empty RelStr holds for D1 be Subset of S1, D2 be Subset of S2 holds for x be Element of S1, y be Element of S2 st ex_sup_of (D1,S1) & ex_sup_of (D2,S2) & for b be Element of [:S1, S2:] st b is_>=_than [:D1, D2:] holds [x, y] <= b holds (for c be Element of S1 st c is_>=_than D1 holds x <= c) & for d be Element of S2 st d is_>=_than D2 holds y <= d

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be Subset of S1, D2 be Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: ex_sup_of (D1,S1) and

       A2: ex_sup_of (D2,S2) and

       A3: for b be Element of [:S1, S2:] st b is_>=_than [:D1, D2:] holds [x, y] <= b;

      thus for c be Element of S1 st c is_>=_than D1 holds x <= c

      proof

        

         A4: ( sup D2) is_>=_than D2 by A2, YELLOW_0: 30;

        let b be Element of S1;

        assume b is_>=_than D1;

        then [x, y] <= [b, ( sup D2)] by A3, A4, Th30;

        hence thesis by Th11;

      end;

      

       A5: ( sup D1) is_>=_than D1 by A1, YELLOW_0: 30;

      let b be Element of S2;

      assume b is_>=_than D2;

      then [x, y] <= [( sup D1), b] by A3, A5, Th30;

      hence thesis by Th11;

    end;

    theorem :: YELLOW_3:36

    

     Th36: for S1,S2 be antisymmetric non empty RelStr holds for D1 be Subset of S1, D2 be Subset of S2 holds for x be Element of S1, y be Element of S2 st ex_inf_of (D1,S1) & ex_inf_of (D2,S2) & for b be Element of [:S1, S2:] st b is_<=_than [:D1, D2:] holds [x, y] >= b holds (for c be Element of S1 st c is_<=_than D1 holds x >= c) & for d be Element of S2 st d is_<=_than D2 holds y >= d

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be Subset of S1, D2 be Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: ex_inf_of (D1,S1) and

       A2: ex_inf_of (D2,S2) and

       A3: for b be Element of [:S1, S2:] st b is_<=_than [:D1, D2:] holds [x, y] >= b;

      thus for c be Element of S1 st c is_<=_than D1 holds x >= c

      proof

        

         A4: ( inf D2) is_<=_than D2 by A2, YELLOW_0: 31;

        let b be Element of S1;

        assume b is_<=_than D1;

        then [x, y] >= [b, ( inf D2)] by A3, A4, Th33;

        hence thesis by Th11;

      end;

      

       A5: ( inf D1) is_<=_than D1 by A1, YELLOW_0: 31;

      let b be Element of S2;

      assume b is_<=_than D2;

      then [x, y] >= [( inf D1), b] by A3, A5, Th33;

      hence thesis by Th11;

    end;

    theorem :: YELLOW_3:37

    for S1,S2 be antisymmetric non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 holds for x be Element of S1, y be Element of S2 st (for c be Element of S1 st c is_>=_than D1 holds x <= c) & for d be Element of S2 st d is_>=_than D2 holds y <= d holds for b be Element of [:S1, S2:] st b is_>=_than [:D1, D2:] holds [x, y] <= b

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: for c be Element of S1 st c is_>=_than D1 holds x <= c and

       A2: for d be Element of S2 st d is_>=_than D2 holds y <= d;

      let b be Element of [:S1, S2:] such that

       A3: b is_>=_than [:D1, D2:];

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then ex c,d be object st c in the carrier of S1 & d in the carrier of S2 & b = [c, d] by ZFMISC_1:def 2;

      then

       A4: b = [(b `1 ), (b `2 )];

      then (b `2 ) is_>=_than D2 by A3, Th29;

      then

       A5: y <= (b `2 ) by A2;

      (b `1 ) is_>=_than D1 by A3, A4, Th29;

      then x <= (b `1 ) by A1;

      hence thesis by A4, A5, Th11;

    end;

    theorem :: YELLOW_3:38

    for S1,S2 be antisymmetric non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 holds for x be Element of S1, y be Element of S2 st (for c be Element of S1 st c is_>=_than D1 holds x >= c) & for d be Element of S2 st d is_>=_than D2 holds y >= d holds for b be Element of [:S1, S2:] st b is_>=_than [:D1, D2:] holds [x, y] >= b

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2, x be Element of S1, y be Element of S2 such that

       A1: for c be Element of S1 st c is_>=_than D1 holds x >= c and

       A2: for d be Element of S2 st d is_>=_than D2 holds y >= d;

      let b be Element of [:S1, S2:] such that

       A3: b is_>=_than [:D1, D2:];

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then ex c,d be object st c in the carrier of S1 & d in the carrier of S2 & b = [c, d] by ZFMISC_1:def 2;

      then

       A4: b = [(b `1 ), (b `2 )];

      then (b `2 ) is_>=_than D2 by A3, Th29;

      then

       A5: y >= (b `2 ) by A2;

      (b `1 ) is_>=_than D1 by A3, A4, Th29;

      then x >= (b `1 ) by A1;

      hence thesis by A4, A5, Th11;

    end;

    theorem :: YELLOW_3:39

    

     Th39: for S1,S2 be antisymmetric non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 holds ex_sup_of (D1,S1) & ex_sup_of (D2,S2) iff ex_sup_of ( [:D1, D2:], [:S1, S2:])

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2;

      hereby

        assume that

         A1: ex_sup_of (D1,S1) and

         A2: ex_sup_of (D2,S2);

        consider a2 be Element of S2 such that

         A3: D2 is_<=_than a2 and

         A4: for b be Element of S2 st D2 is_<=_than b holds a2 <= b by A2, YELLOW_0: 15;

        consider a1 be Element of S1 such that

         A5: D1 is_<=_than a1 and

         A6: for b be Element of S1 st D1 is_<=_than b holds a1 <= b by A1, YELLOW_0: 15;

        ex a be Element of [:S1, S2:] st [:D1, D2:] is_<=_than a & for b be Element of [:S1, S2:] st [:D1, D2:] is_<=_than b holds a <= b

        proof

          take a = [a1, a2];

          thus [:D1, D2:] is_<=_than a by A5, A3, Th30;

          let b be Element of [:S1, S2:] such that

           A7: [:D1, D2:] is_<=_than b;

          the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

          then

           A8: b = [(b `1 ), (b `2 )] by MCART_1: 21;

          then D2 is_<=_than (b `2 ) by A7, Th29;

          then

           A9: a2 <= (b `2 ) by A4;

          D1 is_<=_than (b `1 ) by A7, A8, Th29;

          then a1 <= (b `1 ) by A6;

          hence thesis by A8, A9, Th11;

        end;

        hence ex_sup_of ( [:D1, D2:], [:S1, S2:]) by YELLOW_0: 15;

      end;

      assume ex_sup_of ( [:D1, D2:], [:S1, S2:]);

      then

      consider x be Element of [:S1, S2:] such that

       A10: [:D1, D2:] is_<=_than x and

       A11: for b be Element of [:S1, S2:] st [:D1, D2:] is_<=_than b holds x <= b by YELLOW_0: 15;

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A12: x = [(x `1 ), (x `2 )] by MCART_1: 21;

      then

       A13: D1 is_<=_than (x `1 ) by A10, Th29;

      

       A14: D2 is_<=_than (x `2 ) by A10, A12, Th29;

      for b be Element of S1 st D1 is_<=_than b holds (x `1 ) <= b

      proof

        let b be Element of S1;

        assume D1 is_<=_than b;

        then x <= [b, (x `2 )] by A11, A14, Th30;

        hence thesis by A12, Th11;

      end;

      hence ex_sup_of (D1,S1) by A13, YELLOW_0: 15;

      for b be Element of S2 st D2 is_<=_than b holds (x `2 ) <= b

      proof

        let b be Element of S2;

        assume D2 is_<=_than b;

        then x <= [(x `1 ), b] by A11, A13, Th30;

        hence thesis by A12, Th11;

      end;

      hence thesis by A14, YELLOW_0: 15;

    end;

    theorem :: YELLOW_3:40

    

     Th40: for S1,S2 be antisymmetric non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 holds ex_inf_of (D1,S1) & ex_inf_of (D2,S2) iff ex_inf_of ( [:D1, D2:], [:S1, S2:])

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2;

      hereby

        assume that

         A1: ex_inf_of (D1,S1) and

         A2: ex_inf_of (D2,S2);

        consider a2 be Element of S2 such that

         A3: D2 is_>=_than a2 and

         A4: for b be Element of S2 st D2 is_>=_than b holds a2 >= b by A2, YELLOW_0: 16;

        consider a1 be Element of S1 such that

         A5: D1 is_>=_than a1 and

         A6: for b be Element of S1 st D1 is_>=_than b holds a1 >= b by A1, YELLOW_0: 16;

        ex a be Element of [:S1, S2:] st [:D1, D2:] is_>=_than a & for b be Element of [:S1, S2:] st [:D1, D2:] is_>=_than b holds a >= b

        proof

          take a = [a1, a2];

          thus [:D1, D2:] is_>=_than a by A5, A3, Th33;

          let b be Element of [:S1, S2:] such that

           A7: [:D1, D2:] is_>=_than b;

          the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

          then

           A8: b = [(b `1 ), (b `2 )] by MCART_1: 21;

          then D2 is_>=_than (b `2 ) by A7, Th32;

          then

           A9: a2 >= (b `2 ) by A4;

          D1 is_>=_than (b `1 ) by A7, A8, Th32;

          then a1 >= (b `1 ) by A6;

          hence thesis by A8, A9, Th11;

        end;

        hence ex_inf_of ( [:D1, D2:], [:S1, S2:]) by YELLOW_0: 16;

      end;

      assume ex_inf_of ( [:D1, D2:], [:S1, S2:]);

      then

      consider x be Element of [:S1, S2:] such that

       A10: [:D1, D2:] is_>=_than x and

       A11: for b be Element of [:S1, S2:] st [:D1, D2:] is_>=_than b holds x >= b by YELLOW_0: 16;

      the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A12: x = [(x `1 ), (x `2 )] by MCART_1: 21;

      then

       A13: D1 is_>=_than (x `1 ) by A10, Th32;

      

       A14: D2 is_>=_than (x `2 ) by A10, A12, Th32;

      for b be Element of S1 st D1 is_>=_than b holds (x `1 ) >= b

      proof

        let b be Element of S1;

        assume D1 is_>=_than b;

        then x >= [b, (x `2 )] by A11, A14, Th33;

        hence thesis by A12, Th11;

      end;

      hence ex_inf_of (D1,S1) by A13, YELLOW_0: 16;

      for b be Element of S2 st D2 is_>=_than b holds (x `2 ) >= b

      proof

        let b be Element of S2;

        assume D2 is_>=_than b;

        then x >= [(x `1 ), b] by A11, A13, Th33;

        hence thesis by A12, Th11;

      end;

      hence thesis by A14, YELLOW_0: 16;

    end;

    theorem :: YELLOW_3:41

    

     Th41: for S1,S2 be antisymmetric non empty RelStr holds for D be Subset of [:S1, S2:] holds ex_sup_of (( proj1 D),S1) & ex_sup_of (( proj2 D),S2) iff ex_sup_of (D, [:S1, S2:])

    proof

      let S1,S2 be antisymmetric non empty RelStr, D be Subset of [:S1, S2:];

      

       A1: the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A2: D c= [:( proj1 D), ( proj2 D):] by Th1;

      hereby

        assume that

         A3: ex_sup_of (( proj1 D),S1) and

         A4: ex_sup_of (( proj2 D),S2);

        ex a be Element of [:S1, S2:] st D is_<=_than a & for b be Element of [:S1, S2:] st D is_<=_than b holds a <= b

        proof

          consider x2 be Element of S2 such that

           A5: ( proj2 D) is_<=_than x2 and

           A6: for b be Element of S2 st ( proj2 D) is_<=_than b holds x2 <= b by A4, YELLOW_0: 15;

          consider x1 be Element of S1 such that

           A7: ( proj1 D) is_<=_than x1 and

           A8: for b be Element of S1 st ( proj1 D) is_<=_than b holds x1 <= b by A3, YELLOW_0: 15;

          take a = [x1, x2];

          thus D is_<=_than a

          proof

            let q be Element of [:S1, S2:];

            assume q in D;

            then

            consider q1,q2 be object such that

             A9: q1 in ( proj1 D) and

             A10: q2 in ( proj2 D) and

             A11: q = [q1, q2] by A2, ZFMISC_1:def 2;

            reconsider q2 as Element of S2 by A10;

            reconsider q1 as Element of S1 by A9;

            q1 <= x1 & q2 <= x2 by A7, A5, A9, A10;

            hence thesis by A11, Th11;

          end;

          let b be Element of [:S1, S2:] such that

           A12: D is_<=_than b;

          

           A13: b = [(b `1 ), (b `2 )] by A1, MCART_1: 21;

          then ( proj2 D) is_<=_than (b `2 ) by A12, Th31;

          then

           A14: x2 <= (b `2 ) by A6;

          ( proj1 D) is_<=_than (b `1 ) by A12, A13, Th31;

          then x1 <= (b `1 ) by A8;

          hence thesis by A13, A14, Th11;

        end;

        hence ex_sup_of (D, [:S1, S2:]) by YELLOW_0: 15;

      end;

      assume ex_sup_of (D, [:S1, S2:]);

      then

      consider x be Element of [:S1, S2:] such that

       A15: D is_<=_than x and

       A16: for b be Element of [:S1, S2:] st D is_<=_than b holds x <= b by YELLOW_0: 15;

      

       A17: x = [(x `1 ), (x `2 )] by A1, MCART_1: 21;

      then

       A18: ( proj1 D) is_<=_than (x `1 ) by A15, Th31;

      

       A19: ( proj2 D) is_<=_than (x `2 ) by A15, A17, Th31;

      for b be Element of S1 st ( proj1 D) is_<=_than b holds (x `1 ) <= b

      proof

        let b be Element of S1;

        assume ( proj1 D) is_<=_than b;

        then D is_<=_than [b, (x `2 )] by A19, Th31;

        then x <= [b, (x `2 )] by A16;

        hence thesis by A17, Th11;

      end;

      hence ex_sup_of (( proj1 D),S1) by A18, YELLOW_0: 15;

      for b be Element of S2 st ( proj2 D) is_<=_than b holds (x `2 ) <= b

      proof

        let b be Element of S2;

        assume ( proj2 D) is_<=_than b;

        then D is_<=_than [(x `1 ), b] by A18, Th31;

        then x <= [(x `1 ), b] by A16;

        hence thesis by A17, Th11;

      end;

      hence thesis by A19, YELLOW_0: 15;

    end;

    theorem :: YELLOW_3:42

    

     Th42: for S1,S2 be antisymmetric non empty RelStr holds for D be Subset of [:S1, S2:] holds ex_inf_of (( proj1 D),S1) & ex_inf_of (( proj2 D),S2) iff ex_inf_of (D, [:S1, S2:])

    proof

      let S1,S2 be antisymmetric non empty RelStr, D be Subset of [:S1, S2:];

      

       A1: the carrier of [:S1, S2:] = [:the carrier of S1, the carrier of S2:] by Def2;

      then

       A2: D c= [:( proj1 D), ( proj2 D):] by Th1;

      hereby

        assume that

         A3: ex_inf_of (( proj1 D),S1) and

         A4: ex_inf_of (( proj2 D),S2);

        ex a be Element of [:S1, S2:] st D is_>=_than a & for b be Element of [:S1, S2:] st D is_>=_than b holds a >= b

        proof

          consider x2 be Element of S2 such that

           A5: ( proj2 D) is_>=_than x2 and

           A6: for b be Element of S2 st ( proj2 D) is_>=_than b holds x2 >= b by A4, YELLOW_0: 16;

          consider x1 be Element of S1 such that

           A7: ( proj1 D) is_>=_than x1 and

           A8: for b be Element of S1 st ( proj1 D) is_>=_than b holds x1 >= b by A3, YELLOW_0: 16;

          take a = [x1, x2];

          thus D is_>=_than a

          proof

            let q be Element of [:S1, S2:];

            assume q in D;

            then

            consider q1,q2 be object such that

             A9: q1 in ( proj1 D) and

             A10: q2 in ( proj2 D) and

             A11: q = [q1, q2] by A2, ZFMISC_1:def 2;

            reconsider q2 as Element of S2 by A10;

            reconsider q1 as Element of S1 by A9;

            q1 >= x1 & q2 >= x2 by A7, A5, A9, A10;

            hence thesis by A11, Th11;

          end;

          let b be Element of [:S1, S2:] such that

           A12: D is_>=_than b;

          

           A13: b = [(b `1 ), (b `2 )] by A1, MCART_1: 21;

          then ( proj2 D) is_>=_than (b `2 ) by A12, Th34;

          then

           A14: x2 >= (b `2 ) by A6;

          ( proj1 D) is_>=_than (b `1 ) by A12, A13, Th34;

          then x1 >= (b `1 ) by A8;

          hence thesis by A13, A14, Th11;

        end;

        hence ex_inf_of (D, [:S1, S2:]) by YELLOW_0: 16;

      end;

      assume ex_inf_of (D, [:S1, S2:]);

      then

      consider x be Element of [:S1, S2:] such that

       A15: D is_>=_than x and

       A16: for b be Element of [:S1, S2:] st D is_>=_than b holds x >= b by YELLOW_0: 16;

      

       A17: x = [(x `1 ), (x `2 )] by A1, MCART_1: 21;

      then

       A18: ( proj1 D) is_>=_than (x `1 ) by A15, Th34;

      

       A19: ( proj2 D) is_>=_than (x `2 ) by A15, A17, Th34;

      for b be Element of S1 st ( proj1 D) is_>=_than b holds (x `1 ) >= b

      proof

        let b be Element of S1;

        assume ( proj1 D) is_>=_than b;

        then D is_>=_than [b, (x `2 )] by A19, Th34;

        then x >= [b, (x `2 )] by A16;

        hence thesis by A17, Th11;

      end;

      hence ex_inf_of (( proj1 D),S1) by A18, YELLOW_0: 16;

      for b be Element of S2 st ( proj2 D) is_>=_than b holds (x `2 ) >= b

      proof

        let b be Element of S2;

        assume ( proj2 D) is_>=_than b;

        then D is_>=_than [(x `1 ), b] by A18, Th34;

        then x >= [(x `1 ), b] by A16;

        hence thesis by A17, Th11;

      end;

      hence thesis by A19, YELLOW_0: 16;

    end;

    theorem :: YELLOW_3:43

    

     Th43: for S1,S2 be antisymmetric non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 st ex_sup_of (D1,S1) & ex_sup_of (D2,S2) holds ( sup [:D1, D2:]) = [( sup D1), ( sup D2)]

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2 such that

       A1: ex_sup_of (D1,S1) & ex_sup_of (D2,S2);

      set s = ( sup [:D1, D2:]);

      s is Element of [:the carrier of S1, the carrier of S2:] by Def2;

      then

      consider s1,s2 be object such that

       A2: s1 in the carrier of S1 and

       A3: s2 in the carrier of S2 and

       A4: s = [s1, s2] by ZFMISC_1:def 2;

      reconsider s2 as Element of S2 by A3;

      reconsider s1 as Element of S1 by A2;

      

       A5: ex_sup_of ( [:D1, D2:], [:S1, S2:]) by A1, Th39;

      then

       A6: [s1, s2] is_>=_than [:D1, D2:] by A4, YELLOW_0: 30;

      then

       A7: s1 is_>=_than D1 by Th29;

      

       A8: for b be Element of [:S1, S2:] st b is_>=_than [:D1, D2:] holds [s1, s2] <= b by A4, A5, YELLOW_0: 30;

      then for b be Element of S1 st b is_>=_than D1 holds s1 <= b by A1, Th35;

      then

       A9: s1 = ( sup D1) by A7, YELLOW_0: 30;

      

       A10: s2 is_>=_than D2 by A6, Th29;

      for b be Element of S2 st b is_>=_than D2 holds s2 <= b by A1, A8, Th35;

      hence thesis by A4, A9, A10, YELLOW_0: 30;

    end;

    theorem :: YELLOW_3:44

    

     Th44: for S1,S2 be antisymmetric non empty RelStr holds for D1 be non empty Subset of S1, D2 be non empty Subset of S2 st ex_inf_of (D1,S1) & ex_inf_of (D2,S2) holds ( inf [:D1, D2:]) = [( inf D1), ( inf D2)]

    proof

      let S1,S2 be antisymmetric non empty RelStr, D1 be non empty Subset of S1, D2 be non empty Subset of S2 such that

       A1: ex_inf_of (D1,S1) & ex_inf_of (D2,S2);

      set s = ( inf [:D1, D2:]);

      s is Element of [:the carrier of S1, the carrier of S2:] by Def2;

      then

      consider s1,s2 be object such that

       A2: s1 in the carrier of S1 and

       A3: s2 in the carrier of S2 and

       A4: s = [s1, s2] by ZFMISC_1:def 2;

      reconsider s2 as Element of S2 by A3;

      reconsider s1 as Element of S1 by A2;

      

       A5: ex_inf_of ( [:D1, D2:], [:S1, S2:]) by A1, Th40;

      then

       A6: [s1, s2] is_<=_than [:D1, D2:] by A4, YELLOW_0: 31;

      then

       A7: s1 is_<=_than D1 by Th32;

      

       A8: for b be Element of [:S1, S2:] st b is_<=_than [:D1, D2:] holds [s1, s2] >= b by A4, A5, YELLOW_0: 31;

      then for b be Element of S1 st b is_<=_than D1 holds s1 >= b by A1, Th36;

      then

       A9: s1 = ( inf D1) by A7, YELLOW_0: 31;

      

       A10: s2 is_<=_than D2 by A6, Th32;

      for b be Element of S2 st b is_<=_than D2 holds s2 >= b by A1, A8, Th36;

      hence thesis by A4, A9, A10, YELLOW_0: 31;

    end;

    registration

      let X,Y be complete antisymmetric non empty RelStr;

      cluster [:X, Y:] -> complete;

      coherence

      proof

        set IT = [:X, Y:];

        for D be Subset of IT holds ex_sup_of (D,IT)

        proof

          let D be Subset of IT;

           ex_sup_of (( proj1 D),X) & ex_sup_of (( proj2 D),Y) by YELLOW_0: 17;

          hence thesis by Th41;

        end;

        hence thesis by YELLOW_0: 53;

      end;

    end

    theorem :: YELLOW_3:45

    for X,Y be non empty lower-bounded antisymmetric RelStr st [:X, Y:] is complete holds X is complete & Y is complete

    proof

      let X,Y be non empty lower-bounded antisymmetric RelStr such that

       A1: [:X, Y:] is complete;

      for A be Subset of X holds ex_sup_of (A,X)

      proof

        let A be Subset of X;

        per cases ;

          suppose

           A2: A is non empty;

          set B = the non empty Subset of Y;

           ex_sup_of ( [:A, B:], [:X, Y:]) by A1, YELLOW_0: 17;

          hence thesis by A2, Th39;

        end;

          suppose A is empty;

          hence thesis by YELLOW_0: 42;

        end;

      end;

      hence X is complete by YELLOW_0: 53;

      for B be Subset of Y holds ex_sup_of (B,Y)

      proof

        let B be Subset of Y;

        per cases ;

          suppose

           A3: B is non empty;

          set A = the non empty Subset of X;

           ex_sup_of ( [:A, B:], [:X, Y:]) by A1, YELLOW_0: 17;

          hence thesis by A3, Th39;

        end;

          suppose B is empty;

          hence thesis by YELLOW_0: 42;

        end;

      end;

      hence thesis by YELLOW_0: 53;

    end;

    theorem :: YELLOW_3:46

    for L1,L2 be antisymmetric non empty RelStr holds for D be non empty Subset of [:L1, L2:] st [:L1, L2:] is complete or ex_sup_of (D, [:L1, L2:]) holds ( sup D) = [( sup ( proj1 D)), ( sup ( proj2 D))]

    proof

      let L1,L2 be antisymmetric non empty RelStr, D be non empty Subset of [:L1, L2:];

      reconsider C1 = the carrier of L1, C2 = the carrier of L2 as non empty set;

      the carrier of [:L1, L2:] = [:C1, C2:] by Def2;

      then

      consider d1,d2 be object such that

       A1: d1 in C1 and

       A2: d2 in C2 and

       A3: ( sup D) = [d1, d2] by ZFMISC_1:def 2;

      reconsider d1 as Element of L1 by A1;

      reconsider D9 = D as non empty Subset of [:C1, C2:] by Def2;

      ( proj1 D9) is non empty;

      then

      reconsider D1 = ( proj1 D) as non empty Subset of L1;

      ( proj2 D9) is non empty;

      then

      reconsider D2 = ( proj2 D) as non empty Subset of L2;

      

       A4: D9 c= [:D1, D2:] by Th1;

      reconsider d2 as Element of L2 by A2;

      assume [:L1, L2:] is complete or ex_sup_of (D, [:L1, L2:]);

      then

       A5: ex_sup_of (D, [:L1, L2:]) by YELLOW_0: 17;

      then

       A6: ex_sup_of (D2,L2) by Th41;

      

       A7: ex_sup_of (D1,L1) by A5, Th41;

      then ex_sup_of ( [:D1, D2:], [:L1, L2:]) by A6, Th39;

      then ( sup D) <= ( sup [:D1, D2:]) by A5, A4, YELLOW_0: 34;

      then

       A8: ( sup D) <= [( sup ( proj1 D)), ( sup ( proj2 D))] by A7, A6, Th43;

      D2 is_<=_than d2

      proof

        let b be Element of L2;

        assume b in D2;

        then

        consider x be object such that

         A9: [x, b] in D by XTUPLE_0:def 13;

        reconsider x as Element of D1 by A9, XTUPLE_0:def 12;

        reconsider x as Element of L1;

        D is_<=_than [d1, d2] by A5, A3, YELLOW_0:def 9;

        then [x, b] <= [d1, d2] by A9;

        hence thesis by Th11;

      end;

      then

       A10: ( sup D2) <= d2 by A6, YELLOW_0:def 9;

      D1 is_<=_than d1

      proof

        let b be Element of L1;

        assume b in D1;

        then

        consider x be object such that

         A11: [b, x] in D by XTUPLE_0:def 12;

        reconsider x as Element of D2 by A11, XTUPLE_0:def 13;

        reconsider x as Element of L2;

        D is_<=_than [d1, d2] by A5, A3, YELLOW_0:def 9;

        then [b, x] <= [d1, d2] by A11;

        hence thesis by Th11;

      end;

      then ( sup D1) <= d1 by A7, YELLOW_0:def 9;

      then [( sup D1), ( sup D2)] <= ( sup D) by A3, A10, Th11;

      hence thesis by A8, ORDERS_2: 2;

    end;

    theorem :: YELLOW_3:47

    for L1,L2 be antisymmetric non empty RelStr holds for D be non empty Subset of [:L1, L2:] st [:L1, L2:] is complete or ex_inf_of (D, [:L1, L2:]) holds ( inf D) = [( inf ( proj1 D)), ( inf ( proj2 D))]

    proof

      let L1,L2 be antisymmetric non empty RelStr, D be non empty Subset of [:L1, L2:];

      reconsider C1 = the carrier of L1, C2 = the carrier of L2 as non empty set;

      the carrier of [:L1, L2:] = [:C1, C2:] by Def2;

      then

      consider d1,d2 be object such that

       A1: d1 in C1 and

       A2: d2 in C2 and

       A3: ( inf D) = [d1, d2] by ZFMISC_1:def 2;

      reconsider d1 as Element of L1 by A1;

      reconsider D9 = D as non empty Subset of [:C1, C2:] by Def2;

      ( proj1 D9) is non empty;

      then

      reconsider D1 = ( proj1 D) as non empty Subset of L1;

      ( proj2 D9) is non empty;

      then

      reconsider D2 = ( proj2 D) as non empty Subset of L2;

      

       A4: D9 c= [:D1, D2:] by Th1;

      reconsider d2 as Element of L2 by A2;

      assume [:L1, L2:] is complete or ex_inf_of (D, [:L1, L2:]);

      then

       A5: ex_inf_of (D, [:L1, L2:]) by YELLOW_0: 17;

      then

       A6: ex_inf_of (D2,L2) by Th42;

      

       A7: ex_inf_of (D1,L1) by A5, Th42;

      then ex_inf_of ( [:D1, D2:], [:L1, L2:]) by A6, Th40;

      then ( inf D) >= ( inf [:D1, D2:]) by A5, A4, YELLOW_0: 35;

      then

       A8: ( inf D) >= [( inf ( proj1 D)), ( inf ( proj2 D))] by A7, A6, Th44;

      D2 is_>=_than d2

      proof

        let b be Element of L2;

        assume b in D2;

        then

        consider x be object such that

         A9: [x, b] in D by XTUPLE_0:def 13;

        reconsider x as Element of D1 by A9, XTUPLE_0:def 12;

        reconsider x as Element of L1;

        D is_>=_than [d1, d2] by A5, A3, YELLOW_0:def 10;

        then [x, b] >= [d1, d2] by A9;

        hence thesis by Th11;

      end;

      then

       A10: ( inf D2) >= d2 by A6, YELLOW_0:def 10;

      D1 is_>=_than d1

      proof

        let b be Element of L1;

        assume b in D1;

        then

        consider x be object such that

         A11: [b, x] in D by XTUPLE_0:def 12;

        reconsider x as Element of D2 by A11, XTUPLE_0:def 13;

        reconsider x as Element of L2;

        D is_>=_than [d1, d2] by A5, A3, YELLOW_0:def 10;

        then [b, x] >= [d1, d2] by A11;

        hence thesis by Th11;

      end;

      then ( inf D1) >= d1 by A7, YELLOW_0:def 10;

      then [( inf D1), ( inf D2)] >= ( inf D) by A3, A10, Th11;

      hence thesis by A8, ORDERS_2: 2;

    end;

    theorem :: YELLOW_3:48

    for S1,S2 be non empty reflexive RelStr holds for D be non empty directed Subset of [:S1, S2:] holds [:( proj1 D), ( proj2 D):] c= ( downarrow D)

    proof

      let S1,S2 be non empty reflexive RelStr, D be non empty directed Subset of [:S1, S2:];

      reconsider C1 = the carrier of S1, C2 = the carrier of S2 as non empty set;

      let q be object;

      reconsider D9 = D as non empty Subset of [:C1, C2:] by Def2;

      set D1 = ( proj1 D), D2 = ( proj2 D);

      

       A1: ( downarrow D) = { x where x be Element of [:S1, S2:] : ex y be Element of [:S1, S2:] st x <= y & y in D } by WAYBEL_0: 14;

      

       A2: D9 c= [:D1, D2:] by Th1;

      ( proj2 D9) is non empty;

      then

      reconsider D2 as non empty Subset of S2;

      ( proj1 D9) is non empty;

      then

      reconsider D1 as non empty Subset of S1;

      assume q in [:( proj1 D), ( proj2 D):];

      then

      consider d,e be object such that

       A3: d in D1 and

       A4: e in D2 and

       A5: q = [d, e] by ZFMISC_1:def 2;

      consider y be object such that

       A6: [d, y] in D by A3, XTUPLE_0:def 12;

      consider x be object such that

       A7: [x, e] in D by A4, XTUPLE_0:def 13;

      reconsider y, e as Element of D2 by A6, A7, XTUPLE_0:def 13;

      reconsider x, d as Element of D1 by A6, A7, XTUPLE_0:def 12;

      consider z be Element of [:S1, S2:] such that

       A8: z in D and

       A9: [d, y] <= z & [x, e] <= z by A6, A7, WAYBEL_0:def 1;

      consider z1,z2 be object such that

       A10: z1 in D1 and

       A11: z2 in D2 and

       A12: z = [z1, z2] by A2, A8, ZFMISC_1:def 2;

      reconsider z2 as Element of D2 by A11;

      reconsider z1 as Element of D1 by A10;

      d <= z1 & e <= z2 by A9, A10, A11, A12, Th11;

      then [d, e] <= [z1, z2] by Th11;

      hence thesis by A5, A1, A8, A12;

    end;

    theorem :: YELLOW_3:49

    for S1,S2 be non empty reflexive RelStr holds for D be non empty filtered Subset of [:S1, S2:] holds [:( proj1 D), ( proj2 D):] c= ( uparrow D)

    proof

      let S1,S2 be non empty reflexive RelStr, D be non empty filtered Subset of [:S1, S2:];

      reconsider C1 = the carrier of S1, C2 = the carrier of S2 as non empty set;

      let q be object;

      reconsider D9 = D as non empty Subset of [:C1, C2:] by Def2;

      set D1 = ( proj1 D), D2 = ( proj2 D);

      

       A1: ( uparrow D) = { x where x be Element of [:S1, S2:] : ex y be Element of [:S1, S2:] st x >= y & y in D } by WAYBEL_0: 15;

      

       A2: D9 c= [:D1, D2:] by Th1;

      ( proj2 D9) is non empty;

      then

      reconsider D2 as non empty Subset of S2;

      ( proj1 D9) is non empty;

      then

      reconsider D1 as non empty Subset of S1;

      assume q in [:( proj1 D), ( proj2 D):];

      then

      consider d,e be object such that

       A3: d in D1 and

       A4: e in D2 and

       A5: q = [d, e] by ZFMISC_1:def 2;

      consider y be object such that

       A6: [d, y] in D by A3, XTUPLE_0:def 12;

      consider x be object such that

       A7: [x, e] in D by A4, XTUPLE_0:def 13;

      reconsider y, e as Element of D2 by A6, A7, XTUPLE_0:def 13;

      reconsider x, d as Element of D1 by A6, A7, XTUPLE_0:def 12;

      consider z be Element of [:S1, S2:] such that

       A8: z in D and

       A9: [d, y] >= z & [x, e] >= z by A6, A7, WAYBEL_0:def 2;

      consider z1,z2 be object such that

       A10: z1 in D1 and

       A11: z2 in D2 and

       A12: z = [z1, z2] by A2, A8, ZFMISC_1:def 2;

      reconsider z2 as Element of D2 by A11;

      reconsider z1 as Element of D1 by A10;

      d >= z1 & e >= z2 by A9, A10, A11, A12, Th11;

      then [d, e] >= [z1, z2] by Th11;

      hence thesis by A5, A1, A8, A12;

    end;

    scheme :: YELLOW_3:sch6

    Kappa2DS { X,Y,Z() -> non empty RelStr , F( set, set) -> set } :

ex f be Function of [:X(), Y():], Z() st for x be Element of X(), y be Element of Y() holds (f . (x,y)) = F(x,y)

      provided

       A1: for x be Element of X(), y be Element of Y() holds F(x,y) is Element of Z();

      

       A2: for x be Element of X(), y be Element of Y() holds F(x,y) in the carrier of Z()

      proof

        let x be Element of X(), y be Element of Y();

        reconsider x1 = x as Element of X();

        reconsider y1 = y as Element of Y();

        F(x1,y1) is Element of Z() by A1;

        hence thesis;

      end;

      consider f be Function of [:the carrier of X(), the carrier of Y():], the carrier of Z() such that

       A3: for x be Element of X(), y be Element of Y() holds (f . (x,y)) = F(x,y) from FUNCT_7:sch 1( A2);

      the carrier of [:X(), Y():] = [:the carrier of X(), the carrier of Y():] by Def2;

      then

      reconsider f as Function of [:X(), Y():], Z();

      take f;

      thus thesis by A3;

    end;