robbins4.miz



    begin

    registration

      let L be Lattice;

      cluster the LattStr of L -> Lattice-like;

      coherence by ROBBINS3: 15;

    end

    theorem :: ROBBINS4:1

    

     Th1: for K,L be Lattice st the LattStr of K = the LattStr of L holds ( LattPOSet K) = ( LattPOSet L)

    proof

      let K,L be Lattice;

      assume

       A1: the LattStr of K = the LattStr of L;

      for p,q be Element of K holds [p, q] in ( LattRel K) iff [p, q] in ( LattRel L)

      proof

        let p,q be Element of K;

        reconsider p9 = p, q9 = q as Element of L by A1;

        hereby

          assume [p, q] in ( LattRel K);

          then p [= q by FILTER_1: 31;

          then (p "\/" q) = q;

          then (p9 "\/" q9) = q9 by A1;

          then p9 [= q9;

          hence [p, q] in ( LattRel L) by FILTER_1: 31;

        end;

        assume [p, q] in ( LattRel L);

        then p9 [= q9 by FILTER_1: 31;

        then (p9 "\/" q9) = q9;

        then (p "\/" q) = q by A1;

        then p [= q;

        hence thesis by FILTER_1: 31;

      end;

      hence thesis by A1, RELSET_1:def 2;

    end;

    registration

      cluster -> meet-Absorbing for 1 -element OrthoLattStr;

      coherence ;

    end

    registration

      cluster -> lower-bounded for Ortholattice;

      coherence

      proof

        let IT be Ortholattice;

        ex c be Element of IT st for a be Element of IT holds (c "/\" a) = c & (a "/\" c) = c

        proof

          set x = the Element of IT;

          take c = ((((x ` ) ` ) "\/" (x ` )) ` );

          let a be Element of IT;

          

          thus (c "/\" a) = (((((a ` ) ` ) "\/" (a ` )) ` ) "/\" a) by ROBBINS3:def 7

          .= (((a ` ) "/\" a) "/\" a) by ROBBINS1:def 23

          .= ((a ` ) "/\" (a "/\" a)) by LATTICES:def 7

          .= ((a ` ) "/\" a)

          .= ((((a ` ) ` ) "\/" (a ` )) ` ) by ROBBINS1:def 23

          .= c by ROBBINS3:def 7;

          hence thesis;

        end;

        hence thesis;

      end;

      cluster -> upper-bounded for Ortholattice;

      coherence

      proof

        let IT be Ortholattice;

        ex c be Element of IT st for a be Element of IT holds (c "\/" a) = c & (a "\/" c) = c

        proof

          set x = the Element of IT;

          take c = ((x ` ) "\/" x);

          let a be Element of IT;

          (c "\/" a) = (((a ` ) "\/" a) "\/" a) by ROBBINS3:def 7

          .= ((a ` ) "\/" (a "\/" a)) by LATTICES:def 5

          .= ((a ` ) "\/" a)

          .= c by ROBBINS3:def 7;

          hence thesis;

        end;

        hence thesis;

      end;

    end

    reserve L for Ortholattice,

a,b,c for Element of L;

    theorem :: ROBBINS4:2

    

     Th2: (a "\/" (a ` )) = ( Top L) & (a "/\" (a ` )) = ( Bottom L)

    proof

      

       A1: ((a "\/" (a ` )) "\/" b) = (a "\/" (a ` ))

      proof

        

        thus ((a "\/" (a ` )) "\/" b) = ((b "\/" (b ` )) "\/" b) by ROBBINS3:def 7

        .= ((b ` ) "\/" (b "\/" b)) by LATTICES:def 5

        .= ((b ` ) "\/" b)

        .= (a "\/" (a ` )) by ROBBINS3:def 7;

      end;

      then (b "\/" (a "\/" (a ` ))) = (a "\/" (a ` ));

      hence (a "\/" (a ` )) = ( Top L) by A1, LATTICES:def 17;

      

       A2: ((a "/\" (a ` )) "/\" b) = (a "/\" (a ` ))

      proof

        

        thus ((a "/\" (a ` )) "/\" b) = ((((a ` ) "\/" ((a ` ) ` )) ` ) "/\" b) by ROBBINS1:def 23

        .= ((((b ` ) "\/" ((b ` ) ` )) ` ) "/\" b) by ROBBINS3:def 7

        .= ((b "/\" (b ` )) "/\" b) by ROBBINS1:def 23

        .= ((b ` ) "/\" (b "/\" b)) by LATTICES:def 7

        .= ((b ` ) "/\" b)

        .= ((((b ` ) ` ) "\/" (b ` )) ` ) by ROBBINS1:def 23

        .= ((((a ` ) ` ) "\/" (a ` )) ` ) by ROBBINS3:def 7

        .= (a "/\" (a ` )) by ROBBINS1:def 23;

      end;

      then (b "/\" (a "/\" (a ` ))) = (a "/\" (a ` ));

      hence thesis by A2, LATTICES:def 16;

    end;

    theorem :: ROBBINS4:3

    

     Th3: for L be non empty OrthoLattStr holds L is Ortholattice iff (for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a)) & (for a,b be Element of L holds a = (a "/\" (a "\/" b))) & for a,b be Element of L holds a = (a "\/" (b "/\" (b ` )))

    proof

      let L be non empty OrthoLattStr;

      thus L is Ortholattice implies (for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a)) & (for a,b be Element of L holds a = (a "/\" (a "\/" b))) & for a,b be Element of L holds a = (a "\/" (b "/\" (b ` )))

      proof

        assume

         A1: L is Ortholattice;

        thus for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a)

        proof

          let a,b,c be Element of L;

          ((((c ` ) "/\" (b ` )) ` ) "\/" a) = ((((((c ` ) ` ) "\/" ((b ` ) ` )) ` ) ` ) "\/" a) by A1, ROBBINS1:def 23;

          then ((((c ` ) "/\" (b ` )) ` ) "\/" a) = ((((c "\/" ((b ` ) ` )) ` ) ` ) "\/" a) by A1, ROBBINS3:def 6;

          then ((((c ` ) "/\" (b ` )) ` ) "\/" a) = ((((c "\/" b) ` ) ` ) "\/" a) by A1, ROBBINS3:def 6;

          then ((((c ` ) "/\" (b ` )) ` ) "\/" a) = ((c "\/" b) "\/" a) by A1, ROBBINS3:def 6;

          then ((((c ` ) "/\" (b ` )) ` ) "\/" a) = (a "\/" (c "\/" b)) by A1, LATTICES:def 4;

          then ((((c ` ) "/\" (b ` )) ` ) "\/" a) = (c "\/" (a "\/" b)) by A1, ROBBINS3:def 1;

          hence thesis by A1, LATTICES:def 4;

        end;

        thus for a,b be Element of L holds a = (a "/\" (a "\/" b)) by A1, LATTICES:def 9;

        let a,b be Element of L;

        

        thus (a "\/" (b "/\" (b ` ))) = (a "\/" (((b ` ) "\/" ((b ` ) ` )) ` )) by A1, ROBBINS1:def 23

        .= (a "\/" (((b ` ) "\/" b) ` )) by A1, ROBBINS3:def 6

        .= (a "\/" ((b "\/" (b ` )) ` )) by A1, LATTICES:def 4

        .= (a "\/" ((a "\/" (a ` )) ` )) by A1, ROBBINS3:def 7

        .= (a "\/" ((((a ` ) ` ) "\/" (a ` )) ` )) by A1, ROBBINS3:def 6

        .= (a "\/" ((a ` ) "/\" a)) by A1, ROBBINS1:def 23

        .= (((a ` ) "/\" a) "\/" a) by A1, LATTICES:def 4

        .= a by A1, LATTICES:def 8;

      end;

      assume

       A2: for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a);

      assume

       A3: for a,b be Element of L holds a = (a "/\" (a "\/" b));

      assume

       A4: for a,b be Element of L holds a = (a "\/" (b "/\" (b ` )));

      

       A5: for a be Element of L holds (a "/\" a) = a

      proof

        let a be Element of L;

        

        thus (a "/\" a) = (a "/\" (a "\/" (a "/\" (a ` )))) by A4

        .= a by A3;

      end;

      

       A6: for a,b be Element of L holds a = ((((b "/\" (b ` )) ` ) ` ) "\/" a)

      proof

        let a,b be Element of L;

        set x = (b "/\" (b ` ));

        ((a "\/" x) "\/" x) = ((((x ` ) "/\" (x ` )) ` ) "\/" a) by A2;

        then ((a "\/" x) "\/" x) = (((x ` ) ` ) "\/" a) by A5;

        then (a "\/" x) = (((x ` ) ` ) "\/" a) by A4;

        hence thesis by A4;

      end;

      

       A7: for a be Element of L holds (a "/\" (a ` )) = (((a "/\" (a ` )) ` ) ` )

      proof

        let a be Element of L;

        set x = (a "/\" (a ` ));

        

        thus x = (((x ` ) ` ) "\/" x) by A6

        .= ((x ` ) ` ) by A4;

      end;

      

       A8: for a,b be Element of L holds a = ((b "/\" (b ` )) "\/" a)

      proof

        let a,b be Element of L;

        a = ((((b "/\" (b ` )) ` ) ` ) "\/" a) by A6;

        hence thesis by A7;

      end;

      

       A9: for a,b be Element of L holds (a "\/" b) = (((b ` ) "/\" (a ` )) ` )

      proof

        let a,b be Element of L;

        set x = (a "/\" (a ` ));

        ((x "\/" a) "\/" b) = ((((b ` ) "/\" (a ` )) ` ) "\/" x) by A2;

        

        hence (a "\/" b) = ((((b ` ) "/\" (a ` )) ` ) "\/" x) by A8

        .= (((b ` ) "/\" (a ` )) ` ) by A4;

      end;

      

       A10: L is involutive

      proof

        let a be Element of L;

        (a ` ) = ((a ` ) "/\" ((a ` ) "\/" a)) & ((a ` ) "\/" a) = (((a ` ) "/\" ((a ` ) ` )) ` ) by A3, A9;

        

        hence ((a ` ) ` ) = (((a ` ) "/\" ((a ` ) ` )) "\/" a) by A9

        .= a by A8;

      end;

      

       A11: L is join-commutative

      proof

        let a,b be Element of L;

        set x = (a "/\" (a ` ));

        (x "\/" b) = (((b ` ) "/\" (x ` )) ` ) by A9;

        

        hence (b "\/" a) = ((((b ` ) "/\" (x ` )) ` ) "\/" a) by A8

        .= ((a "\/" x) "\/" b) by A2

        .= (a "\/" b) by A4;

      end;

      

       A12: L is de_Morgan

      proof

        let a,b be Element of L;

        

        thus (((a ` ) "\/" (b ` )) ` ) = (((b ` ) "\/" (a ` )) ` ) by A11

        .= (((((a ` ) ` ) "/\" ((b ` ) ` )) ` ) ` ) by A9

        .= (((a ` ) ` ) "/\" ((b ` ) ` )) by A10

        .= (((a ` ) ` ) "/\" b) by A10

        .= (a "/\" b) by A10;

      end;

      

       A13: L is meet-absorbing

      proof

        let a,b be Element of L;

        

        thus ((a "/\" b) "\/" b) = (((b ` ) "/\" ((a "/\" b) ` )) ` ) by A9

        .= (((b ` ) "/\" ((((a ` ) "\/" (b ` )) ` ) ` )) ` ) by A12

        .= (((b ` ) "/\" ((a ` ) "\/" (b ` ))) ` ) by A10

        .= (((b ` ) "/\" ((b ` ) "\/" (a ` ))) ` ) by A11

        .= ((b ` ) ` ) by A3

        .= b by A10;

      end;

      

       A14: L is join-associative

      proof

        let a,b,c be Element of L;

        

        thus ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a) by A2

        .= ((b "\/" c) "\/" a) by A9

        .= (a "\/" (b "\/" c)) by A11;

      end;

      

       A15: L is meet-associative

      proof

        let a,b,c be Element of L;

        

        thus (a "/\" (b "/\" c)) = (((a ` ) "\/" ((b "/\" c) ` )) ` ) by A12

        .= (((a ` ) "\/" ((((b ` ) "\/" (c ` )) ` ) ` )) ` ) by A12

        .= (((a ` ) "\/" ((b ` ) "\/" (c ` ))) ` ) by A10

        .= ((((a ` ) "\/" (b ` )) "\/" (c ` )) ` ) by A14

        .= ((((((a ` ) "\/" (b ` )) ` ) ` ) "\/" (c ` )) ` ) by A10

        .= ((((a "/\" b) ` ) "\/" (c ` )) ` ) by A12

        .= ((a "/\" b) "/\" c) by A12;

      end;

      

       A16: for a,b be Element of L holds (a "/\" (a ` )) = (b "/\" (b ` ))

      proof

        let a,b be Element of L;

        (a "/\" (a ` )) = ((a "/\" (a ` )) "\/" (b "/\" (b ` ))) by A4;

        hence thesis by A8;

      end;

      

       A17: L is with_Top

      proof

        let a,b be Element of L;

        (((a ` ) "/\" ((a ` ) ` )) ` ) = (((b ` ) "/\" ((b ` ) ` )) ` ) by A16;

        then (((a ` ) "/\" ((a ` ) ` )) ` ) = ((b ` ) "\/" b) by A9;

        then ((a ` ) "\/" a) = ((b ` ) "\/" b) by A9;

        then ((a ` ) "\/" a) = (b "\/" (b ` )) by A11;

        hence thesis by A11;

      end;

      L is join-absorbing by A3;

      hence thesis by A11, A14, A10, A12, A17, A15, A13;

    end;

    theorem :: ROBBINS4:4

    

     Th4: for L be involutive Lattice-like non empty OrthoLattStr holds L is de_Morgan iff for a,b be Element of L st a [= b holds (b ` ) [= (a ` )

    proof

      let L be involutive Lattice-like non empty OrthoLattStr;

      thus L is de_Morgan implies for a,b be Element of L st a [= b holds (b ` ) [= (a ` )

      proof

        assume

         A1: L is de_Morgan;

        let a,b be Element of L;

        assume a [= b;

        

        then (a ` ) = ((a "/\" b) ` ) by LATTICES: 4

        .= ((((a ` ) "\/" (b ` )) ` ) ` ) by A1

        .= ((b ` ) "\/" (a ` )) by ROBBINS3:def 6;

        then ((a ` ) "/\" (b ` )) = (b ` ) by LATTICES:def 9;

        hence thesis by LATTICES: 4;

      end;

      assume

       A2: for a,b be Element of L st a [= b holds (b ` ) [= (a ` );

      let x,y be Element of L;

      (((x ` ) "\/" (y ` )) ` ) [= ((y ` ) ` ) by A2, LATTICES: 5;

      then

       A3: (((x ` ) "\/" (y ` )) ` ) [= y by ROBBINS3:def 6;

      (x ` ) [= ((x "/\" y) ` ) & (y ` ) [= ((x "/\" y) ` ) by A2, LATTICES: 6;

      then ((x ` ) "\/" (y ` )) [= ((x "/\" y) ` ) by FILTER_0: 6;

      then (((x "/\" y) ` ) ` ) [= (((x ` ) "\/" (y ` )) ` ) by A2;

      then

       A4: (x "/\" y) [= (((x ` ) "\/" (y ` )) ` ) by ROBBINS3:def 6;

      (((x ` ) "\/" (y ` )) ` ) [= ((x ` ) ` ) by A2, LATTICES: 5;

      then (((x ` ) "\/" (y ` )) ` ) [= x by ROBBINS3:def 6;

      then (((x ` ) "\/" (y ` )) ` ) [= (x "/\" y) by A3, FILTER_0: 7;

      hence thesis by A4, LATTICES: 8;

    end;

    begin

    definition

      let L be non empty OrthoLattStr;

      :: ROBBINS4:def1

      attr L is orthomodular means

      : Def1: for x,y be Element of L st x [= y holds y = (x "\/" ((x ` ) "/\" y));

    end

    registration

      cluster trivial orthomodular modular Boolean for Ortholattice;

      existence

      proof

        set L = the 1 -element Ortholattice;

        L is orthomodular by STRUCT_0:def 10;

        hence thesis;

      end;

    end

    theorem :: ROBBINS4:5

    

     Th5: for L be modular Ortholattice holds L is orthomodular

    proof

      let L be modular Ortholattice;

      let x,y be Element of L;

      assume x [= y;

      then (x "\/" ((x ` ) "/\" y)) = ((x "\/" (x ` )) "/\" y) by LATTICES:def 12;

      then (x "\/" ((x ` ) "/\" y)) = ((y "\/" (y ` )) "/\" y) by ROBBINS3:def 7;

      hence thesis by LATTICES:def 9;

    end;

    definition

      mode Orthomodular_Lattice is orthomodular Ortholattice;

    end

    theorem :: ROBBINS4:6

    

     Th6: for L be orthomodular meet-absorbing join-absorbing join-associative meet-commutative non empty OrthoLattStr, x,y be Element of L holds (x "\/" ((x ` ) "/\" (x "\/" y))) = (x "\/" y) by LATTICES: 5, Def1;

    definition

      let L be non empty OrthoLattStr;

      :: ROBBINS4:def2

      attr L is Orthomodular means

      : Def2: for x,y be Element of L holds (x "\/" ((x ` ) "/\" (x "\/" y))) = (x "\/" y);

    end

    registration

      cluster Orthomodular -> orthomodular for meet-absorbing join-absorbing join-associative meet-commutative non empty OrthoLattStr;

      coherence

      proof

        let L be meet-absorbing join-absorbing join-associative meet-commutative non empty OrthoLattStr;

        assume

         A1: L is Orthomodular;

        let x,y be Element of L;

        assume x [= y;

        then (x "\/" y) = y;

        hence thesis by A1;

      end;

      cluster orthomodular -> Orthomodular for meet-absorbing join-absorbing join-associative meet-commutative non empty OrthoLattStr;

      coherence by Th6;

    end

    registration

      cluster modular -> orthomodular for Ortholattice;

      coherence by Th5;

    end

    registration

      cluster join-Associative meet-Absorbing de_Morgan orthomodular for Ortholattice;

      existence

      proof

        set L = the 1 -element Ortholattice;

        take L;

        thus thesis;

      end;

    end

    begin

    definition

      :: ROBBINS4:def3

      func B_6 -> RelStr equals ( InclPoset { 0 , 1, (3 \ 1), 2, (3 \ 2), 3});

      coherence ;

    end

    registration

      cluster B_6 -> non empty;

      coherence ;

      cluster B_6 -> reflexive transitive antisymmetric;

      coherence ;

    end

    

     Lm1: (3 \ 2) misses 2 by XBOOLE_1: 79;

    

     Lm2: ( Segm 1) c= ( Segm 2) by NAT_1: 39;

    then

     Lm3: (3 \ 2) misses 1 by Lm1, XBOOLE_1: 63;

    registration

      cluster B_6 -> with_suprema with_infima;

      coherence

      proof

        set N = B_6 ;

        set Z = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3};

        

         A1: the carrier of N = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by YELLOW_1: 1;

        

         A2: N is with_suprema

        proof

          let x,y be Element of N;

          

           A3: Z = the carrier of N by YELLOW_1: 1;

          thus ex z be Element of N st x <= z & y <= z & for z9 be Element of N st x <= z9 & y <= z9 holds z <= z9

          proof

            per cases by A3, ENUMSET1:def 4;

              suppose x = 0 & y = 0 ;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = (3 \ 1);

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = 2;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = (3 \ 2);

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = 3;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 1) & y = 0 ;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 1) & y = (3 \ 1);

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A4: x = (3 \ 1) & y = 2;

              3 in Z by ENUMSET1:def 4;

              then

              reconsider z = 3 as Element of N by YELLOW_1: 1;

              take z;

              ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              hence x <= z & y <= z by A4, YELLOW_1: 3;

              let z9 be Element of N;

              assume that

               A5: x <= z9 and

               A6: y <= z9;

              

               A7: z9 is Element of Z by YELLOW_1: 1;

              

               A8: (3 \ 1) c= z9 by A4, A5, YELLOW_1: 3;

               A9:

              now

                assume z9 = 2;

                then

                 A10: not 2 in z9;

                2 in (3 \ 1) by TARSKI:def 2, YELLOW11: 3;

                hence contradiction by A8, A10;

              end;

              

               A11: ( Segm 2) c= z9 by A4, A6, YELLOW_1: 3;

               A12:

              now

                

                 A13: 0 in 2 by CARD_1: 50, TARSKI:def 2;

                assume z9 = (3 \ 1);

                hence contradiction by A11, A13, TARSKI:def 2, YELLOW11: 3;

              end;

               A14:

              now

                

                 A15: ( Segm 1) in ( Segm 2) by CARD_1: 50, TARSKI:def 2;

                assume z9 = (3 \ 2);

                hence contradiction by A11, A15, TARSKI:def 1, YELLOW11: 4;

              end;

              1 in 2 & 0 in 2 by TARSKI:def 2, CARD_1: 50;

              then 1 in z9 & 0 in z9 by A11;

              then z9 <> 1 & z9 <> 0 ;

              hence thesis by A7, A12, A9, A14, ENUMSET1:def 4;

            end;

              suppose x = 1 & y = 0 ;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 1 & y = 1;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A16: x = 1 & y = (3 \ 1);

              

               A17: ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              (1 \/ (3 \ 1)) = (1 \/ 3) by XBOOLE_1: 39

              .= 3 by A17, XBOOLE_1: 12;

              then

              reconsider z = (x \/ y) as Element of N by A1, A16, ENUMSET1:def 4;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A18: x = 1 & y = (3 \ 2);

              3 in Z by ENUMSET1:def 4;

              then

              reconsider z = 3 as Element of N by YELLOW_1: 1;

              take z;

              ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              hence x <= z & y <= z by A18, YELLOW_1: 3;

              let z9 be Element of N;

              assume that

               A19: x <= z9 and

               A20: y <= z9;

              

               A21: (3 \ 2) c= z9 by A18, A20, YELLOW_1: 3;

               A22:

              now

                

                 A23: 2 in (3 \ 2) by TARSKI:def 1, YELLOW11: 4;

                assume z9 = 1;

                hence contradiction by A21, A23, CARD_1: 49, TARSKI:def 1;

              end;

               A24:

              now

                assume z9 = 2;

                then

                 A25: not 2 in z9;

                2 in (3 \ 2) by TARSKI:def 1, YELLOW11: 4;

                hence contradiction by A21, A25;

              end;

              

               A26: 1 c= z9 by A18, A19, YELLOW_1: 3;

               A27:

              now

                

                 A28: 0 in 1 by CARD_1: 49, TARSKI:def 1;

                assume z9 = (3 \ 1);

                hence contradiction by A26, A28, TARSKI:def 2, YELLOW11: 3;

              end;

               A29:

              now

                

                 A30: 0 in 1 by CARD_1: 49, TARSKI:def 1;

                assume z9 = (3 \ 2);

                hence contradiction by A26, A30, TARSKI:def 1, YELLOW11: 4;

              end;

              z9 is Element of Z & z9 <> 0 by A26, YELLOW_1: 1;

              hence thesis by A27, A24, A29, A22, ENUMSET1:def 4;

            end;

              suppose

               A31: x = 1 & y = 3;

              ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x \/ y) as Element of N by A31, XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A32: x = 1 & y = 2;

              ( Segm 1) c= ( Segm 2) by NAT_1: 39;

              then

              reconsider z = (x \/ y) as Element of N by A32, XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose y = 1 & x = 0 ;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose y = 1 & x = 1;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A33: y = 1 & x = (3 \ 1);

              

               A34: ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              (1 \/ (3 \ 1)) = (1 \/ 3) by XBOOLE_1: 39

              .= 3 by A34, XBOOLE_1: 12;

              then

              reconsider z = (x \/ y) as Element of N by A1, A33, ENUMSET1:def 4;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A35: y = 1 & x = (3 \ 2);

              3 in Z by ENUMSET1:def 4;

              then

              reconsider z = 3 as Element of N by YELLOW_1: 1;

              take z;

              ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              hence x <= z & y <= z by A35, YELLOW_1: 3;

              let z9 be Element of N;

              assume that

               A36: x <= z9 and

               A37: y <= z9;

              

               A38: (3 \ 2) c= z9 by A35, A36, YELLOW_1: 3;

               A39:

              now

                

                 A40: 2 in (3 \ 2) by TARSKI:def 1, YELLOW11: 4;

                assume z9 = 1;

                hence contradiction by A38, A40, CARD_1: 49, TARSKI:def 1;

              end;

               A41:

              now

                assume z9 = 2;

                then

                 A42: not 2 in z9;

                2 in (3 \ 2) by TARSKI:def 1, YELLOW11: 4;

                hence contradiction by A38, A42;

              end;

              

               A43: 1 c= z9 by A35, A37, YELLOW_1: 3;

               A44:

              now

                

                 A45: 0 in 1 by CARD_1: 49, TARSKI:def 1;

                assume z9 = (3 \ 1);

                hence contradiction by A43, A45, TARSKI:def 2, YELLOW11: 3;

              end;

               A46:

              now

                

                 A47: 0 in 1 by CARD_1: 49, TARSKI:def 1;

                assume z9 = (3 \ 2);

                hence contradiction by A43, A47, TARSKI:def 1, YELLOW11: 4;

              end;

              z9 is Element of Z & z9 <> 0 by A43, YELLOW_1: 1;

              hence thesis by A44, A41, A46, A39, ENUMSET1:def 4;

            end;

              suppose

               A48: y = 1 & x = 3;

              ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x \/ y) as Element of N by A48, XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A49: y = 1 & x = 2;

              ( Segm 1) c= ( Segm 2) by NAT_1: 39;

              then

              reconsider z = (x \/ y) as Element of N by A49, XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 1) & y = (3 \ 2);

              then

              reconsider z = (x \/ y) as Element of N by Lm2, XBOOLE_1: 12, XBOOLE_1: 34;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 1) & y = 3;

              then

              reconsider z = (x \/ y) as Element of N by XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 2 & y = 0 ;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A50: x = 2 & y = (3 \ 1);

              3 in Z by ENUMSET1:def 4;

              then

              reconsider z = 3 as Element of N by YELLOW_1: 1;

              take z;

              ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              hence x <= z & y <= z by A50, YELLOW_1: 3;

              let z9 be Element of N;

              assume that

               A51: x <= z9 and

               A52: y <= z9;

              

               A53: z9 is Element of Z by YELLOW_1: 1;

              

               A54: (3 \ 1) c= z9 by A50, A52, YELLOW_1: 3;

               A55:

              now

                assume z9 = 2;

                then

                 A56: not 2 in z9;

                2 in (3 \ 1) by TARSKI:def 2, YELLOW11: 3;

                hence contradiction by A54, A56;

              end;

              

               A57: 2 c= z9 by A50, A51, YELLOW_1: 3;

               A58:

              now

                

                 A59: 0 in 2 by CARD_1: 50, TARSKI:def 2;

                assume z9 = (3 \ 1);

                hence contradiction by A57, A59, TARSKI:def 2, YELLOW11: 3;

              end;

               A60:

              now

                

                 A61: 1 in 2 by CARD_1: 50, TARSKI:def 2;

                assume z9 = (3 \ 2);

                hence contradiction by A57, A61, TARSKI:def 1, YELLOW11: 4;

              end;

              1 in 2 & 0 in 2 by CARD_1: 50, TARSKI:def 2;

              then 1 in z9 & 0 in z9 by A57;

              then z9 <> 1 & z9 <> 0 ;

              hence thesis by A53, A58, A55, A60, ENUMSET1:def 4;

            end;

              suppose x = 2 & y = 2;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A62: x = 2 & y = (3 \ 2);

              

               A63: ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              (2 \/ (3 \ 2)) = (2 \/ 3) by XBOOLE_1: 39

              .= 3 by A63, XBOOLE_1: 12;

              then (x \/ y) in Z by A62, ENUMSET1:def 4;

              then

              reconsider z = (x \/ y) as Element of N by YELLOW_1: 1;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A64: x = 2 & y = 3;

              ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x \/ y) as Element of N by A64, XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 2) & y = 0 ;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 2) & y = (3 \ 1);

              then

              reconsider z = (x \/ y) as Element of N by Lm2, XBOOLE_1: 12, XBOOLE_1: 34;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A65: x = (3 \ 2) & y = 2;

              

               A66: ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              (2 \/ (3 \ 2)) = (2 \/ 3) by XBOOLE_1: 39

              .= 3 by A66, XBOOLE_1: 12;

              then (x \/ y) in Z by A65, ENUMSET1:def 4;

              then

              reconsider z = (x \/ y) as Element of N by YELLOW_1: 1;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 2) & y = (3 \ 2);

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 2) & y = 3;

              then

              reconsider z = (x \/ y) as Element of N by XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 3 & y = 0 ;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 3 & y = (3 \ 1);

              then

              reconsider z = (x \/ y) as Element of N by XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A67: x = 3 & y = 2;

              ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x \/ y) as Element of N by A67, XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 3 & y = (3 \ 2);

              then

              reconsider z = (x \/ y) as Element of N by XBOOLE_1: 12;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 3 & y = 3;

              then

              reconsider z = (x \/ y) as Element of N;

              take z;

              x c= z & y c= z by XBOOLE_1: 7;

              hence x <= z & y <= z by YELLOW_1: 3;

              let w be Element of N;

              assume x <= w & y <= w;

              then x c= w & y c= w by YELLOW_1: 3;

              then (x \/ y) c= w by XBOOLE_1: 8;

              hence thesis by YELLOW_1: 3;

            end;

          end;

        end;

        N is with_infima

        proof

          let x,y be Element of N;

          

           A68: Z = the carrier of N by YELLOW_1: 1;

          thus ex z be Element of N st z <= x & z <= y & for z9 be Element of N st z9 <= x & z9 <= y holds z9 <= z

          proof

            per cases by A68, ENUMSET1:def 4;

              suppose x = 0 & y = 0 ;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = (3 \ 1);

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = 2;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = (3 \ 2);

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 0 & y = 3;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 1) & y = 0 ;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 1) & y = (3 \ 1);

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A69: x = (3 \ 1) & y = 2;

               0 in Z by ENUMSET1:def 4;

              then

              reconsider z = 0 as Element of N by YELLOW_1: 1;

              take z;

              z c= x & z c= y;

              hence z <= x & z <= y by YELLOW_1: 3;

              let z9 be Element of N;

              assume that

               A70: z9 <= x and

               A71: z9 <= y;

              

               A72: z9 c= (3 \ 1) by A69, A70, YELLOW_1: 3;

               A73:

              now

                assume z9 = 2;

                then 0 in z9 by CARD_1: 50, TARSKI:def 2;

                hence contradiction by A72, TARSKI:def 2, YELLOW11: 3;

              end;

              

               A74: z9 c= 2 by A69, A71, YELLOW_1: 3;

               A75:

              now

                assume z9 = (3 \ 1);

                then

                 A76: 2 in z9 by TARSKI:def 2, YELLOW11: 3;

                 not 2 in 2;

                hence contradiction by A74, A76;

              end;

               A77:

              now

                assume z9 = 3;

                then

                 A78: 2 in z9 by CARD_1: 51, ENUMSET1:def 1;

                 not 2 in 2;

                hence contradiction by A74, A78;

              end;

               A79:

              now

                assume z9 = (3 \ 2);

                then

                 A80: 2 in z9 by TARSKI:def 1, YELLOW11: 4;

                 not 2 in 2;

                hence contradiction by A74, A80;

              end;

               A81:

              now

                assume z9 = 1;

                then 0 in z9 by CARD_1: 49, TARSKI:def 1;

                hence contradiction by A72, TARSKI:def 2, YELLOW11: 3;

              end;

              z9 is Element of Z by YELLOW_1: 1;

              hence thesis by A75, A73, A79, A81, A77, ENUMSET1:def 4;

            end;

              suppose x = 1 & y = 0 ;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 1 & y = 1;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 1 & y = (3 \ 1);

              then x misses y by XBOOLE_1: 79;

              then (x /\ y) = 0 by XBOOLE_0:def 7;

              then

              reconsider z = (x /\ y) as Element of N by A1, ENUMSET1:def 4;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 1 & y = (3 \ 2);

              then (x /\ y) = 0 by Lm3, XBOOLE_0:def 7;

              then

              reconsider z = (x /\ y) as Element of N by A1, ENUMSET1:def 4;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A82: x = 1 & y = 3;

              ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x /\ y) as Element of N by A82, XBOOLE_1: 28;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 1 & y = 2;

              then

              reconsider z = (x /\ y) as Element of N by CARD_1: 49, CARD_1: 50, ZFMISC_1: 13;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose y = 1 & x = 0 ;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose y = 1 & x = 1;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose y = 1 & x = (3 \ 1);

              then x misses y by XBOOLE_1: 79;

              then (x /\ y) = 0 by XBOOLE_0:def 7;

              then

              reconsider z = (x /\ y) as Element of N by A1, ENUMSET1:def 4;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose y = 1 & x = (3 \ 2);

              then (x /\ y) = {} by Lm3, XBOOLE_0:def 7;

              then

              reconsider z = (x /\ y) as Element of N by A1, ENUMSET1:def 4;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A83: y = 1 & x = 3;

              ( Segm 1) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x /\ y) as Element of N by A83, XBOOLE_1: 28;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose y = 1 & x = 2;

              then

              reconsider z = (x /\ y) as Element of N by CARD_1: 49, CARD_1: 50, ZFMISC_1: 13;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 1) & y = (3 \ 2);

              then

              reconsider z = (x /\ y) as Element of N by YELLOW11: 3, YELLOW11: 4, ZFMISC_1: 13;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A84: x = (3 \ 1) & y = 3;

              ((3 \ 1) /\ 3) = ((3 /\ 3) \ 1) by XBOOLE_1: 49

              .= (3 \ 1);

              then

              reconsider z = (x /\ y) as Element of N by A84;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 2 & y = 0 ;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A85: x = 2 & y = (3 \ 1);

               0 in Z by ENUMSET1:def 4;

              then

              reconsider z = 0 as Element of N by YELLOW_1: 1;

              take z;

              z c= x & z c= y;

              hence z <= x & z <= y by YELLOW_1: 3;

              let z9 be Element of N;

              assume that

               A86: z9 <= x and

               A87: z9 <= y;

              

               A88: z9 c= (3 \ 1) by A85, A87, YELLOW_1: 3;

               A89:

              now

                assume z9 = 2;

                then 0 in z9 by CARD_1: 50, TARSKI:def 2;

                hence contradiction by A88, TARSKI:def 2, YELLOW11: 3;

              end;

              

               A90: z9 c= 2 by A85, A86, YELLOW_1: 3;

               A91:

              now

                assume z9 = (3 \ 1);

                then

                 A92: 2 in z9 by TARSKI:def 2, YELLOW11: 3;

                 not 2 in 2;

                hence contradiction by A90, A92;

              end;

               A93:

              now

                assume z9 = 3;

                then

                 A94: 2 in z9 by CARD_1: 51, ENUMSET1:def 1;

                 not 2 in 2;

                hence contradiction by A90, A94;

              end;

               A95:

              now

                assume z9 = (3 \ 2);

                then

                 A96: 2 in z9 by TARSKI:def 1, YELLOW11: 4;

                 not 2 in 2;

                hence contradiction by A90, A96;

              end;

               A97:

              now

                assume z9 = 1;

                then 0 in z9 by CARD_1: 49, TARSKI:def 1;

                hence contradiction by A88, TARSKI:def 2, YELLOW11: 3;

              end;

              z9 is Element of Z by YELLOW_1: 1;

              hence thesis by A91, A89, A95, A93, A97, ENUMSET1:def 4;

            end;

              suppose x = 2 & y = 2;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A98: x = 2 & y = (3 \ 2);

              2 misses (3 \ 2) by XBOOLE_1: 79;

              then (2 /\ (3 \ 2)) = 0 by XBOOLE_0:def 7;

              then (x /\ y) in Z by A98, ENUMSET1:def 4;

              then

              reconsider z = (x /\ y) as Element of N by YELLOW_1: 1;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A99: x = 2 & y = 3;

              ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x /\ y) as Element of N by A99, XBOOLE_1: 28;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 2) & y = 0 ;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 2) & y = (3 \ 1);

              then

              reconsider z = (x /\ y) as Element of N by YELLOW11: 3, YELLOW11: 4, ZFMISC_1: 13;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A100: x = (3 \ 2) & y = 2;

              2 misses (3 \ 2) by XBOOLE_1: 79;

              then (2 /\ (3 \ 2)) = 0 by XBOOLE_0:def 7;

              then (x /\ y) in Z by A100, ENUMSET1:def 4;

              then

              reconsider z = (x /\ y) as Element of N by YELLOW_1: 1;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = (3 \ 2) & y = (3 \ 2);

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A101: x = (3 \ 2) & y = 3;

              ((3 \ 2) /\ 3) = ((3 /\ 3) \ 2) by XBOOLE_1: 49

              .= (3 \ 2);

              then

              reconsider z = (x /\ y) as Element of N by A101;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 3 & y = 0 ;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A102: x = 3 & y = (3 \ 1);

              ((3 \ 1) /\ 3) = ((3 /\ 3) \ 1) by XBOOLE_1: 49

              .= (3 \ 1);

              then

              reconsider z = (x /\ y) as Element of N by A102;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A103: x = 3 & y = 2;

              ( Segm 2) c= ( Segm 3) by NAT_1: 39;

              then

              reconsider z = (x /\ y) as Element of N by A103, XBOOLE_1: 28;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose

               A104: x = 3 & y = (3 \ 2);

              ((3 \ 2) /\ 3) = ((3 /\ 3) \ 2) by XBOOLE_1: 49

              .= (3 \ 2);

              then

              reconsider z = (x /\ y) as Element of N by A104;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

              suppose x = 3 & y = 3;

              then

              reconsider z = (x /\ y) as Element of N;

              take z;

              z c= x & z c= y by XBOOLE_1: 17;

              hence z <= x & z <= y by YELLOW_1: 3;

              let w be Element of N;

              assume w <= x & w <= y;

              then w c= x & w c= y by YELLOW_1: 3;

              then w c= (x /\ y) by XBOOLE_1: 19;

              hence thesis by YELLOW_1: 3;

            end;

          end;

        end;

        hence thesis by A2;

      end;

    end

    theorem :: ROBBINS4:7

    

     Th7: the carrier of ( latt B_6 ) = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3}

    proof

       the RelStr of B_6 = ( LattPOSet ( latt B_6 )) by LATTICE3:def 15;

      hence thesis by YELLOW_1: 1;

    end;

    theorem :: ROBBINS4:8

    

     Th8: for a be set st a in the carrier of ( latt B_6 ) holds a c= ( Segm 3)

    proof

      let a be set;

      assume a in the carrier of ( latt B_6 );

      then a = 0 or a = ( Segm 1) or a = (3 \ 1) or a = ( Segm 2) or a = (3 \ 2) or a = 3 by Th7, ENUMSET1:def 4;

      hence thesis by NAT_1: 39;

    end;

    definition

      :: ROBBINS4:def4

      func Benzene -> strict OrthoLattStr means

      : Def4: the LattStr of it = ( latt B_6 ) & for x be Element of it , y be Subset of 3 st x = y holds (the Compl of it . x) = (y ` );

      existence

      proof

        defpred P[ set, set] means for y be Subset of 3 st $1 = y holds $2 = (y ` );

        set N = ( latt B_6 );

        set M = the carrier of N;

        set A = the L_join of N, B = the L_meet of N;

        

         A1: for x be Element of M holds ex y be Element of M st P[x, y]

        proof

          let x be Element of M;

          reconsider z = x as Subset of 3 by Th8;

          

           A2: ( Segm 2) c= ( Segm 3) by NAT_1: 39;

          

           A3: ( Segm 1) c= ( Segm 3) by NAT_1: 39;

          now

            per cases by Th7, ENUMSET1:def 4;

              suppose z = 0 ;

              hence (z ` ) in M by Th7, ENUMSET1:def 4;

            end;

              suppose z = 1;

              hence (z ` ) in M by Th7, ENUMSET1:def 4;

            end;

              suppose z = (3 \ 1);

              

              then (z ` ) = (3 /\ 1) by XBOOLE_1: 48

              .= 1 by A3, XBOOLE_1: 28;

              hence (z ` ) in M by Th7, ENUMSET1:def 4;

            end;

              suppose z = (3 \ 2);

              

              then (z ` ) = (3 /\ 2) by XBOOLE_1: 48

              .= 2 by A2, XBOOLE_1: 28;

              hence (z ` ) in M by Th7, ENUMSET1:def 4;

            end;

              suppose z = 2;

              hence (z ` ) in M by Th7, ENUMSET1:def 4;

            end;

              suppose z = 3;

              then (z ` ) = 0 by XBOOLE_1: 37;

              hence (z ` ) in M by Th7, ENUMSET1:def 4;

            end;

          end;

          then

          reconsider y = (z ` ) as Element of M;

          take y;

          thus thesis;

        end;

        ex f be Function of M, M st for x be Element of M holds P[x, (f . x)] from FUNCT_2:sch 3( A1);

        then

        consider C be UnOp of M such that

         A4: for x be Element of M, y be Subset of 3 st x = y holds (C . x) = (y ` );

        take OrthoLattStr (# M, A, B, C #);

        thus thesis by A4;

      end;

      uniqueness

      proof

        let A1,A2 be strict OrthoLattStr such that

         A5: the LattStr of A1 = ( latt B_6 ) and

         A6: for x be Element of A1, y be Subset of 3 st x = y holds (the Compl of A1 . x) = (y ` ) and

         A7: the LattStr of A2 = ( latt B_6 ) and

         A8: for x be Element of A2, y be Subset of 3 st x = y holds (the Compl of A2 . x) = (y ` );

        set f2 = the Compl of A2;

        set f1 = the Compl of A1;

        set M = the carrier of A1;

        for x be Element of M holds (f1 . x) = (f2 . x)

        proof

          let x be Element of M;

          reconsider y = x as Subset of 3 by A5, Th8;

          

          thus (f1 . x) = (y ` ) by A6

          .= (f2 . x) by A5, A7, A8;

        end;

        hence thesis by A5, A7, FUNCT_2: 63;

      end;

    end

    theorem :: ROBBINS4:9

    

     Th9: the carrier of Benzene = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3}

    proof

       the LattStr of Benzene = the LattStr of ( latt B_6 ) & ( LattPOSet ( latt B_6 )) = the RelStr of B_6 by Def4, LATTICE3:def 15;

      hence thesis by YELLOW_1: 1;

    end;

    theorem :: ROBBINS4:10

    

     Th10: the carrier of Benzene c= ( bool 3)

    proof

      let a be object;

      

       A1: 0 c= 3 & ( Segm 1) c= ( Segm 3) by NAT_1: 39;

      assume

       A2: a in the carrier of Benzene ;

      

       A3: ( Segm 2) c= ( Segm 3) & 3 c= 3 by NAT_1: 39;

      a = 0 or a = 1 or a = (3 \ 1) or a = 2 or a = (3 \ 2) or a = 3 by A2, Th9, ENUMSET1:def 4;

      hence thesis by A1, A3;

    end;

    theorem :: ROBBINS4:11

    

     Th11: for a be set st a in the carrier of Benzene holds a c= { 0 , 1, 2} by Th10, CARD_1: 51;

    registration

      cluster Benzene -> non empty;

      coherence by Th9;

      cluster Benzene -> Lattice-like;

      coherence

      proof

         the LattStr of Benzene = ( latt B_6 ) by Def4;

        hence thesis by ROBBINS3: 15;

      end;

    end

    theorem :: ROBBINS4:12

    

     Th12: ( LattPOSet the LattStr of Benzene ) = B_6

    proof

      ( LattPOSet the LattStr of Benzene ) = ( LattPOSet ( latt B_6 )) by Def4;

      hence thesis by LATTICE3:def 15;

    end;

    theorem :: ROBBINS4:13

    

     Th13: for a,b be Element of B_6 , x,y be Element of Benzene st a = x & b = y holds a <= b iff x [= y

    proof

      let a,b be Element of B_6 , x,y be Element of Benzene ;

      assume

       A1: a = x & b = y;

      hereby

        assume a <= b;

        then (x % ) <= (y % ) by A1, Th1, Th12;

        hence x [= y by LATTICE3: 7;

      end;

      assume x [= y;

      then (x % ) <= (y % ) by LATTICE3: 7;

      hence thesis by A1, Th1, Th12;

    end;

    theorem :: ROBBINS4:14

    

     Th14: for a,b be Element of B_6 , x,y be Element of Benzene st a = x & b = y holds (a "\/" b) = (x "\/" y) & (a "/\" b) = (x "/\" y)

    proof

      let a,b be Element of B_6 , x,y be Element of Benzene ;

      reconsider xy = (x "\/" y) as Element of B_6 by Th9, YELLOW_1: 1;

      assume that

       A1: a = x and

       A2: b = y;

      x [= (x "\/" y) by LATTICES: 5;

      then

       A3: a <= xy by A1, Th13;

      

       A4: for d be Element of B_6 st d >= a & d >= b holds xy <= d

      proof

        let d be Element of B_6 ;

        reconsider e = d as Element of Benzene by Th9, YELLOW_1: 1;

        assume d >= a & d >= b;

        then x [= e & y [= e by A1, A2, Th13;

        then (x "\/" y) [= e by FILTER_0: 6;

        hence thesis by Th13;

      end;

      y [= (x "\/" y) by LATTICES: 5;

      then

       A5: b <= xy by A2, Th13;

      reconsider xy = (x "/\" y) as Element of B_6 by Th9, YELLOW_1: 1;

      (x "/\" y) [= y by LATTICES: 6;

      then

       A6: xy <= b by A2, Th13;

      

       A7: for d be Element of B_6 st d <= a & d <= b holds xy >= d

      proof

        let d be Element of B_6 ;

        reconsider e = d as Element of Benzene by Th9, YELLOW_1: 1;

        assume d <= a & d <= b;

        then e [= x & e [= y by A1, A2, Th13;

        then e [= (x "/\" y) by FILTER_0: 7;

        hence thesis by Th13;

      end;

      (x "/\" y) [= x by LATTICES: 6;

      then xy <= a by A1, Th13;

      hence thesis by A3, A5, A4, A6, A7, YELLOW_0: 22, YELLOW_0: 23;

    end;

    theorem :: ROBBINS4:15

    

     Th15: for a,b be Element of B_6 st a = (3 \ 1) & b = 2 holds (a "\/" b) = 3 & (a "/\" b) = 0

    proof

      3 in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} & 0 in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by ENUMSET1:def 4;

      then

      reconsider t = 3, z = 0 as Element of B_6 by YELLOW_1: 1;

      let a,b be Element of B_6 ;

      assume that

       A1: a = (3 \ 1) and

       A2: b = 2;

      ( Segm 2) c= ( Segm 3) by NAT_1: 39;

      then

       A3: b <= t by YELLOW_1: 3, A2;

      

       A4: the carrier of B_6 = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by YELLOW_1: 1;

      

       A5: for d be Element of B_6 st d >= a & d >= b holds t <= d

      proof

        let z9 be Element of B_6 ;

        assume that

         A6: z9 >= a and

         A7: z9 >= b;

        

         A8: ( Segm 2) c= z9 by A2, A7, YELLOW_1: 3;

         A9:

        now

          

           A10: 0 in 2 by CARD_1: 50, TARSKI:def 2;

          assume z9 = (3 \ 1);

          hence contradiction by A8, A10, TARSKI:def 2, YELLOW11: 3;

        end;

        

         A11: (3 \ 1) c= z9 by A1, A6, YELLOW_1: 3;

         A12:

        now

          assume z9 = 2;

          then

           A13: not 2 in z9;

          2 in (3 \ 1) by TARSKI:def 2, YELLOW11: 3;

          hence contradiction by A11, A13;

        end;

         A14:

        now

          

           A15: 1 in 2 by CARD_1: 50, TARSKI:def 2;

          assume z9 = (3 \ 2);

          hence contradiction by A8, A15, TARSKI:def 1, YELLOW11: 4;

        end;

        1 in 2 & 0 in 2 by TARSKI:def 2, CARD_1: 50;

        then 1 in z9 & 0 in z9 by A8;

        then z9 <> 1 & z9 <> 0 ;

        hence thesis by A4, A9, A12, A14, ENUMSET1:def 4;

      end;

      

       A16: for d be Element of B_6 st a >= d & b >= d holds d <= z

      proof

        let z9 be Element of B_6 ;

        assume that

         A17: a >= z9 and

         A18: b >= z9;

        

         A19: z9 c= (3 \ 1) by A1, A17, YELLOW_1: 3;

         A20:

        now

          assume z9 = 1;

          then 0 in z9 by CARD_1: 49, TARSKI:def 1;

          hence contradiction by A19, TARSKI:def 2, YELLOW11: 3;

        end;

        

         A21: z9 c= 2 by A2, A18, YELLOW_1: 3;

         A22:

        now

          assume z9 = (3 \ 1);

          then

           A23: 2 in z9 by TARSKI:def 2, YELLOW11: 3;

           not 2 in 2;

          hence contradiction by A21, A23;

        end;

         A24:

        now

          assume z9 = 3;

          then

           A25: 2 in z9 by CARD_1: 51, ENUMSET1:def 1;

           not 2 in 2;

          hence contradiction by A21, A25;

        end;

         A26:

        now

          assume z9 = (3 \ 2);

          then

           A27: 2 in z9 by TARSKI:def 1, YELLOW11: 4;

           not 2 in 2;

          hence contradiction by A21, A27;

        end;

        now

          assume z9 = 2;

          then 0 in z9 by CARD_1: 50, TARSKI:def 2;

          hence contradiction by A19, TARSKI:def 2, YELLOW11: 3;

        end;

        hence thesis by A4, A22, A26, A20, A24, ENUMSET1:def 4;

      end;

      z c= b;

      then

       A28: z <= b by YELLOW_1: 3;

      z c= a;

      then

       A29: z <= a by YELLOW_1: 3;

      a <= t by A1, YELLOW_1: 3;

      hence thesis by A3, A5, A29, A28, A16, YELLOW_0: 22, YELLOW_0: 23;

    end;

    theorem :: ROBBINS4:16

    

     Th16: for a,b be Element of B_6 st a = (3 \ 2) & b = 1 holds (a "\/" b) = 3 & (a "/\" b) = 0

    proof

      3 in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} & 0 in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by ENUMSET1:def 4;

      then

      reconsider t = 3, z = 0 as Element of B_6 by YELLOW_1: 1;

      let a,b be Element of B_6 ;

      assume that

       A1: a = (3 \ 2) and

       A2: b = 1;

      ( Segm 1) c= ( Segm 3) by NAT_1: 39;

      then

       A3: b <= t by YELLOW_1: 3, A2;

      

       A4: the carrier of B_6 = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by YELLOW_1: 1;

      

       A5: for d be Element of B_6 st d >= a & d >= b holds t <= d

      proof

        let z9 be Element of B_6 ;

        assume that

         A6: z9 >= a and

         A7: z9 >= b;

        

         A8: (3 \ 2) c= z9 by A1, A6, YELLOW_1: 3;

         A9:

        now

          

           A10: 2 in (3 \ 2) by TARSKI:def 1, YELLOW11: 4;

          assume z9 = 1;

          hence contradiction by A8, A10, CARD_1: 49, TARSKI:def 1;

        end;

         A11:

        now

          assume z9 = 2;

          then

           A12: not 2 in z9;

          2 in (3 \ 2) by TARSKI:def 1, YELLOW11: 4;

          hence contradiction by A8, A12;

        end;

        

         A13: 1 c= z9 by A2, A7, YELLOW_1: 3;

         A14:

        now

          

           A15: 0 in 1 by CARD_1: 49, TARSKI:def 1;

          assume z9 = (3 \ 2);

          hence contradiction by A13, A15, TARSKI:def 1, YELLOW11: 4;

        end;

         A16:

        now

          

           A17: 0 in 1 by CARD_1: 49, TARSKI:def 1;

          assume z9 = (3 \ 1);

          hence contradiction by A13, A17, TARSKI:def 2, YELLOW11: 3;

        end;

        z9 <> 0 by A13;

        hence thesis by A4, A14, A11, A16, A9, ENUMSET1:def 4;

      end;

      

       A18: for d be Element of B_6 st a >= d & b >= d holds d <= z

      proof

        let z9 be Element of B_6 ;

        assume that

         A19: a >= z9 and

         A20: b >= z9;

        

         A21: z9 c= (3 \ 2) by A1, A19, YELLOW_1: 3;

         A22:

        now

          assume z9 = 1;

          then 0 in z9 by CARD_1: 49, TARSKI:def 1;

          hence contradiction by A21, TARSKI:def 1, YELLOW11: 4;

        end;

        

         A23: z9 c= 1 by A2, A20, YELLOW_1: 3;

         A24:

        now

          assume z9 = (3 \ 2);

          then 2 in z9 by TARSKI:def 1, YELLOW11: 4;

          hence contradiction by A23, CARD_1: 49, TARSKI:def 1;

        end;

         A25:

        now

          assume z9 = (3 \ 1);

          then

           A26: 2 in z9 by TARSKI:def 2, YELLOW11: 3;

           not 2 in 1 by CARD_1: 50, TARSKI:def 2;

          hence contradiction by A23, A26;

        end;

         A27:

        now

          assume z9 = 3;

          then 2 in z9 by CARD_1: 51, ENUMSET1:def 1;

          hence contradiction by A23, CARD_1: 49, TARSKI:def 1;

        end;

        now

          assume z9 = 2;

          then 0 in z9 by CARD_1: 50, TARSKI:def 2;

          hence contradiction by A21, TARSKI:def 1, YELLOW11: 4;

        end;

        hence thesis by A4, A25, A24, A22, A27, ENUMSET1:def 4;

      end;

      z c= b;

      then

       A28: z <= b by YELLOW_1: 3;

      z c= a;

      then

       A29: z <= a by YELLOW_1: 3;

      a <= t by A1, YELLOW_1: 3;

      hence thesis by A3, A5, A29, A28, A18, YELLOW_0: 22, YELLOW_0: 23;

    end;

    theorem :: ROBBINS4:17

    

     Th17: for a,b be Element of B_6 st a = (3 \ 1) & b = 1 holds (a "\/" b) = 3 & (a "/\" b) = 0

    proof

      

       A1: the carrier of B_6 = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by YELLOW_1: 1;

      then

      reconsider z = 3 as Element of B_6 by ENUMSET1:def 4;

      

       A2: ( Segm 1) c= ( Segm 3) by NAT_1: 39;

      let x,y be Element of B_6 ;

      assume that

       A3: x = (3 \ 1) and

       A4: y = 1;

      

       A5: (1 \/ (3 \ 1)) = (1 \/ 3) by XBOOLE_1: 39

      .= 3 by A2, XBOOLE_1: 12;

      now

        thus x <= z & y <= z by A3, YELLOW_1: 3, A2, A4;

        let w be Element of B_6 ;

        assume x <= w & y <= w;

        then x c= w & y c= w by YELLOW_1: 3;

        then (x \/ y) c= w by XBOOLE_1: 8;

        hence z <= w by A3, A4, A5, YELLOW_1: 3;

      end;

      hence (x "\/" y) = 3 by YELLOW_0: 22;

      reconsider z = 0 as Element of B_6 by A1, ENUMSET1:def 4;

      x misses y by A3, A4, XBOOLE_1: 79;

      then

       A6: (x /\ y) = 0 by XBOOLE_0:def 7;

      now

        z c= x & z c= y;

        hence z <= x & z <= y by YELLOW_1: 3;

        let w be Element of B_6 ;

        assume w <= x & w <= y;

        then w c= x & w c= y by YELLOW_1: 3;

        then w c= (x /\ y) by XBOOLE_1: 19;

        hence w <= z by A6;

      end;

      hence thesis by YELLOW_0: 23;

    end;

    theorem :: ROBBINS4:18

    

     Th18: for a,b be Element of B_6 st a = (3 \ 2) & b = 2 holds (a "\/" b) = 3 & (a "/\" b) = 0

    proof

      

       A1: the carrier of B_6 = { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by YELLOW_1: 1;

      then

      reconsider z = 3 as Element of B_6 by ENUMSET1:def 4;

      

       A2: ( Segm 2) c= ( Segm 3) by NAT_1: 39;

      let x,y be Element of B_6 ;

      assume that

       A3: x = (3 \ 2) and

       A4: y = 2;

      

       A5: (2 \/ (3 \ 2)) = (2 \/ 3) by XBOOLE_1: 39

      .= 3 by A2, XBOOLE_1: 12;

      now

        thus x <= z & y <= z by A3, YELLOW_1: 3, A2, A4;

        let w be Element of B_6 ;

        assume x <= w & y <= w;

        then x c= w & y c= w by YELLOW_1: 3;

        then (x \/ y) c= w by XBOOLE_1: 8;

        hence z <= w by A3, A4, A5, YELLOW_1: 3;

      end;

      hence (x "\/" y) = 3 by YELLOW_0: 22;

      reconsider z = 0 as Element of B_6 by A1, ENUMSET1:def 4;

      x misses y by A3, A4, XBOOLE_1: 79;

      then

       A6: (x /\ y) = 0 by XBOOLE_0:def 7;

      now

        z c= x & z c= y;

        hence z <= x & z <= y by YELLOW_1: 3;

        let w be Element of B_6 ;

        assume w <= x & w <= y;

        then w c= x & w c= y by YELLOW_1: 3;

        then w c= (x /\ y) by XBOOLE_1: 19;

        hence w <= z by A6;

      end;

      hence thesis by YELLOW_0: 23;

    end;

    theorem :: ROBBINS4:19

    

     Th19: for a,b be Element of Benzene st a = (3 \ 1) & b = 2 holds (a "\/" b) = 3 & (a "/\" b) = 0

    proof

      let a,b be Element of Benzene ;

      assume

       A1: a = (3 \ 1) & b = 2;

      then a in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} & b in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by ENUMSET1:def 4;

      then

      reconsider aa = a, bb = b as Element of B_6 by YELLOW_1: 1;

      (aa "\/" bb) = 3 & (aa "/\" bb) = 0 by A1, Th15;

      hence thesis by Th14;

    end;

    theorem :: ROBBINS4:20

    for a,b be Element of Benzene st a = (3 \ 2) & b = 1 holds (a "\/" b) = 3

    proof

      let a,b be Element of Benzene ;

      assume

       A1: a = (3 \ 2) & b = 1;

      then a in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} & b in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by ENUMSET1:def 4;

      then

      reconsider aa = a, bb = b as Element of B_6 by YELLOW_1: 1;

      (aa "\/" bb) = 3 by A1, Th16;

      hence thesis by Th14;

    end;

    theorem :: ROBBINS4:21

    

     Th21: for a,b be Element of Benzene st a = (3 \ 1) & b = 1 holds (a "\/" b) = 3

    proof

      let a,b be Element of Benzene ;

      assume

       A1: a = (3 \ 1) & b = 1;

      then a in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} & b in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by ENUMSET1:def 4;

      then

      reconsider aa = a, bb = b as Element of B_6 by YELLOW_1: 1;

      (aa "\/" bb) = 3 by A1, Th17;

      hence thesis by Th14;

    end;

    theorem :: ROBBINS4:22

    

     Th22: for a,b be Element of Benzene st a = (3 \ 2) & b = 2 holds (a "\/" b) = 3

    proof

      let a,b be Element of Benzene ;

      assume

       A1: a = (3 \ 2) & b = 2;

      then a in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} & b in { 0 , 1, (3 \ 1), 2, (3 \ 2), 3} by ENUMSET1:def 4;

      then

      reconsider aa = a, bb = b as Element of B_6 by YELLOW_1: 1;

      (aa "\/" bb) = 3 by A1, Th18;

      hence thesis by Th14;

    end;

    theorem :: ROBBINS4:23

    

     Th23: for a be Element of Benzene holds (a = 0 implies (a ` ) = 3) & (a = 3 implies (a ` ) = 0 ) & (a = 1 implies (a ` ) = (3 \ 1)) & (a = (3 \ 1) implies (a ` ) = 1) & (a = 2 implies (a ` ) = (3 \ 2)) & (a = (3 \ 2) implies (a ` ) = 2)

    proof

      set B = Benzene ;

      let a be Element of Benzene ;

      reconsider c = a as Subset of 3 by Th10;

      

       A1: (a ` ) c= (c ` ) by Def4;

      

       A2: (a ` ) = (c ` ) by Def4;

      hence a = 0 implies (a ` ) = 3;

      

       A3: (a ` ) = {} or (a ` ) = { 0 } or (a ` ) = {1} or (a ` ) = {2} or (a ` ) = { 0 , 1} or (a ` ) = {1, 2} or (a ` ) = { 0 , 2} or (a ` ) = { 0 , 1, 2} by A2, YELLOW11: 1, ZFMISC_1: 118;

      thus a = 3 implies (a ` ) = 0

      proof

        assume

         A4: a = 3;

        then 1 in c by ENUMSET1:def 1, YELLOW11: 1;

        then

         A5: not 1 in (a ` ) by A1, XBOOLE_0:def 5;

        2 in c by A4, ENUMSET1:def 1, YELLOW11: 1;

        then

         A6: not 2 in (a ` ) by A1, XBOOLE_0:def 5;

         not 0 in (c ` ) by A4, XBOOLE_0:def 5;

        then not 0 in (a ` ) by Def4;

        hence thesis by A3, A5, A6, ENUMSET1:def 1, TARSKI:def 1, TARSKI:def 2;

      end;

      thus a = 1 implies (a ` ) = (3 \ 1) by A2;

      

       A7: 0 in 3 by ENUMSET1:def 1, YELLOW11: 1;

      thus a = (3 \ 1) implies (a ` ) = 1

      proof

        assume

         A8: a = (3 \ 1);

        then 1 in c by TARSKI:def 2, YELLOW11: 3;

        then

         A9: not 1 in (a ` ) by A1, XBOOLE_0:def 5;

        2 in c by A8, TARSKI:def 2, YELLOW11: 3;

        then

         A10: not 2 in (a ` ) by A1, XBOOLE_0:def 5;

         not 0 in c by A8, TARSKI:def 2, YELLOW11: 3;

        hence thesis by A7, A2, A3, A9, A10, CARD_1: 49, ENUMSET1:def 1, TARSKI:def 1, TARSKI:def 2, XBOOLE_0:def 5;

      end;

      thus a = 2 implies (a ` ) = (3 \ 2) by A2;

      assume

       A11: a = (3 \ 2);

      then 2 in c by TARSKI:def 1, YELLOW11: 4;

      then

       A12: not 2 in (a ` ) by A1, XBOOLE_0:def 5;

      1 in 3 & not 1 in c by A11, ENUMSET1:def 1, TARSKI:def 1, YELLOW11: 1, YELLOW11: 4;

      then

       A13: 1 in (a ` ) by A2, XBOOLE_0:def 5;

       not 0 in c by A11, TARSKI:def 1, YELLOW11: 4;

      then 0 in (a ` ) by A7, A2, XBOOLE_0:def 5;

      hence thesis by A3, A12, A13, CARD_1: 50, ENUMSET1:def 1, TARSKI:def 1, TARSKI:def 2;

    end;

    theorem :: ROBBINS4:24

    

     Th24: for a,b be Element of Benzene holds a [= b iff a c= b

    proof

      let a,b be Element of Benzene ;

      reconsider x = a, y = b as Element of B_6 by Th9, YELLOW_1: 1;

      hereby

        assume a [= b;

        then x <= y by Th13;

        hence a c= b by YELLOW_1: 3;

      end;

      assume a c= b;

      then x <= y by YELLOW_1: 3;

      hence thesis by Th13;

    end;

    theorem :: ROBBINS4:25

    

     Th25: for a,x be Element of Benzene st a = 0 holds (a "/\" x) = a

    proof

      let a,x be Element of Benzene ;

      assume a = 0 ;

      then a c= x;

      then a [= x by Th24;

      hence thesis by LATTICES: 4;

    end;

    theorem :: ROBBINS4:26

    

     Th26: for a,x be Element of Benzene st a = 0 holds (a "\/" x) = x

    proof

      let a,x be Element of Benzene ;

      assume a = 0 ;

      then a c= x;

      then a [= x by Th24;

      hence thesis;

    end;

    theorem :: ROBBINS4:27

    

     Th27: for a,x be Element of Benzene st a = 3 holds (a "\/" x) = a

    proof

      let a,x be Element of Benzene ;

      assume a = 3;

      then x c= a by Th11, YELLOW11: 1;

      then x [= a by Th24;

      hence thesis;

    end;

    registration

      cluster Benzene -> lower-bounded;

      coherence

      proof

        reconsider B = 0 as Element of Benzene by Th9, ENUMSET1:def 4;

        take B;

        for a be Element of Benzene holds (B "/\" a) = B & (a "/\" B) = B by Th25;

        hence thesis;

      end;

      cluster Benzene -> upper-bounded;

      coherence

      proof

        reconsider B = 3 as Element of Benzene by Th9, ENUMSET1:def 4;

        take B;

        for a be Element of Benzene holds (B "\/" a) = B & (a "\/" B) = B by Th27;

        hence thesis;

      end;

    end

    theorem :: ROBBINS4:28

    ( Top Benzene ) = 3

    proof

      reconsider x = 3 as Element of Benzene by Th9, ENUMSET1:def 4;

      for a be Element of Benzene holds (x "\/" a) = x & (a "\/" x) = x by Th27;

      hence thesis by LATTICES:def 17;

    end;

    theorem :: ROBBINS4:29

    

     Th29: ( Bottom Benzene ) = 0

    proof

      reconsider x = 0 as Element of Benzene by Th9, ENUMSET1:def 4;

      for a be Element of Benzene holds (x "/\" a) = x & (a "/\" x) = x by Th25;

      hence thesis by LATTICES:def 16;

    end;

    registration

      cluster Benzene -> involutive with_Top de_Morgan;

      coherence

      proof

        set B = Benzene ;

        for a be Element of B holds ((a ` ) ` ) = a

        proof

          let a be Element of B;

          per cases by Th9, ENUMSET1:def 4;

            suppose

             A1: a = 0 ;

            then (a ` ) = 3 by Th23;

            hence thesis by A1, Th23;

          end;

            suppose

             A2: a = 1;

            then (a ` ) = (3 \ 1) by Th23;

            hence thesis by A2, Th23;

          end;

            suppose

             A3: a = (3 \ 1);

            then (a ` ) = 1 by Th23;

            hence thesis by A3, Th23;

          end;

            suppose

             A4: a = 2;

            then (a ` ) = (3 \ 2) by Th23;

            hence thesis by A4, Th23;

          end;

            suppose

             A5: a = (3 \ 2);

            then (a ` ) = 2 by Th23;

            hence thesis by A5, Th23;

          end;

            suppose

             A6: a = 3;

            then (a ` ) = 0 by Th23;

            hence thesis by A6, Th23;

          end;

        end;

        hence

         A7: B is involutive;

        

         A8: for a be Element of B holds (a "\/" (a ` )) = 3

        proof

          let a be Element of B;

          per cases by Th9, ENUMSET1:def 4;

            suppose

             A9: a = 0 ;

            then (a ` ) = 3 by Th23;

            hence thesis by A9, Th26;

          end;

            suppose

             A10: a = 1;

            then (a ` ) = (3 \ 1) by Th23;

            hence thesis by A10, Th21;

          end;

            suppose

             A11: a = (3 \ 1);

            then (a ` ) = 1 by Th23;

            hence thesis by A11, Th21;

          end;

            suppose

             A12: a = 2;

            then (a ` ) = (3 \ 2) by Th23;

            hence thesis by A12, Th22;

          end;

            suppose

             A13: a = (3 \ 2);

            then (a ` ) = 2 by Th23;

            hence thesis by A13, Th22;

          end;

            suppose a = 3;

            hence thesis by Th27;

          end;

        end;

        thus B is with_Top

        proof

          let a,b be Element of B;

          (a "\/" (a ` )) = 3 by A8;

          hence thesis by A8;

        end;

        for a,b be Element of B holds a [= b implies (b ` ) [= (a ` )

        proof

          let a,b be Element of B;

          reconsider x = a, y = b as Subset of { 0 , 1, 2} by Th11;

          reconsider x, y as Subset of 3 by CARD_1: 51;

          assume a [= b;

          then x c= y by Th24;

          then

           A14: (y ` ) c= (x ` ) by SUBSET_1: 12;

          (a ` ) = (x ` ) & (b ` ) = (y ` ) by Def4;

          hence thesis by A14, Th24;

        end;

        hence B is de_Morgan by A7, Th4;

      end;

      cluster Benzene -> non orthomodular;

      coherence

      proof

         not for x,y be Element of Benzene st x [= y holds y = (x "\/" ((x ` ) "/\" y))

        proof

          set y = 2;

          set x = 1;

          reconsider x, y as Element of Benzene by Th9, ENUMSET1:def 4;

          for z be object holds z in 1 implies z in 2

          proof

            let z be object;

            assume z in 1;

            then z = 0 by CARD_1: 49, TARSKI:def 1;

            hence thesis by CARD_1: 50, TARSKI:def 2;

          end;

          then 1 c= 2;

          then

           A15: x [= y by Th24;

          (x ` ) = (3 \ 1) by Th23;

          then ((x ` ) "/\" y) = 0 by Th19;

          then (x "\/" ((x ` ) "/\" y)) = x by Th29;

          hence thesis by A15;

        end;

        hence thesis;

      end;

    end

    begin

    definition

      let L be Ortholattice, a,b be Element of L;

      :: ROBBINS4:def5

      pred a,b are_orthogonal means a [= (b ` );

    end

    notation

      let L be Ortholattice, a,b be Element of L;

      synonym a _|_ b for a,b are_orthogonal ;

    end

    theorem :: ROBBINS4:30

    a _|_ a iff a = ( Bottom L)

    proof

      thus a _|_ a implies a = ( Bottom L)

      proof

        assume a _|_ a;

        then a [= (a ` );

        then (a "/\" (a ` )) = a by LATTICES: 4;

        hence thesis by Th2;

      end;

      assume a = ( Bottom L);

      then (a "/\" (a ` )) = a;

      then a [= (a ` ) by LATTICES: 4;

      hence thesis;

    end;

    definition

      let L be Ortholattice;

      let a,b be Element of L;

      :: original: are_orthogonal

      redefine

      pred a,b are_orthogonal ;

      symmetry

      proof

        let a,b be Element of L;

        assume a _|_ b;

        then a [= (b ` );

        then ((b ` ) ` ) [= (a ` ) by Th4;

        then b [= (a ` ) by ROBBINS3:def 6;

        hence thesis;

      end;

    end

    theorem :: ROBBINS4:31

    a _|_ b & a _|_ c implies a _|_ (b "/\" c) & a _|_ (b "\/" c)

    proof

      assume a _|_ b;

      then

       A1: a [= (b ` );

      then

       A2: (a "/\" (c ` )) [= ((b ` ) "/\" (c ` )) by LATTICES: 9;

      assume

       A3: a _|_ c;

      (b ` ) [= ((b ` ) "\/" (c ` )) by LATTICES: 5;

      then a [= ((b ` ) "\/" (c ` )) by A1, LATTICES: 7;

      then a [= ((((b ` ) "\/" (c ` )) ` ) ` ) by ROBBINS3:def 6;

      then a [= ((b "/\" c) ` ) by ROBBINS1:def 23;

      hence a _|_ (b "/\" c);

      a [= (c ` ) by A3;

      then a [= ((b ` ) "/\" (c ` )) by A2, LATTICES: 4;

      then a [= ((((b ` ) ` ) "\/" ((c ` ) ` )) ` ) by ROBBINS1:def 23;

      then a [= ((b "\/" ((c ` ) ` )) ` ) by ROBBINS3:def 6;

      then a [= ((b "\/" c) ` ) by ROBBINS3:def 6;

      hence thesis;

    end;

    begin

    theorem :: ROBBINS4:32

    L is orthomodular iff for a,b be Element of L st (b ` ) [= a & (a "/\" b) = ( Bottom L) holds a = (b ` )

    proof

      thus L is orthomodular implies for a,b be Element of L st (b ` ) [= a & (a "/\" b) = ( Bottom L) holds a = (b ` )

      proof

        assume

         A1: L is orthomodular;

        let x,y be Element of L;

        assume

         A2: (y ` ) [= x;

        assume

         A3: (x "/\" y) = ( Bottom L);

        

        thus x = ((y ` ) "\/" (((y ` ) ` ) "/\" x)) by A1, A2

        .= ((y ` ) "\/" (y "/\" x)) by ROBBINS3:def 6

        .= (y ` ) by A3;

      end;

      assume

       A4: for a,b be Element of L st (b ` ) [= a & (a "/\" b) = ( Bottom L) holds a = (b ` );

      let x,y be Element of L;

      assume x [= y;

      then (x "\/" ((x ` ) "/\" y)) [= (y "\/" ((x ` ) "/\" y)) by FILTER_0: 1;

      then (x "\/" ((x ` ) "/\" y)) [= y by LATTICES:def 8;

      then

       A5: (((x "\/" ((x ` ) "/\" y)) ` ) ` ) [= y by ROBBINS3:def 6;

      (((x "\/" ((x ` ) "/\" y)) ` ) "/\" y) = (y "/\" ((((x ` ) ` ) "\/" ((x ` ) "/\" y)) ` )) by ROBBINS3:def 6

      .= (y "/\" ((((x ` ) ` ) "\/" ((((x ` ) "/\" y) ` ) ` )) ` )) by ROBBINS3:def 6

      .= (y "/\" ((x ` ) "/\" (((x ` ) "/\" y) ` ))) by ROBBINS1:def 23

      .= (y "/\" ((x ` ) "/\" (((((x ` ) ` ) "\/" (y ` )) ` ) ` ))) by ROBBINS1:def 23

      .= (y "/\" ((x ` ) "/\" (((x ` ) ` ) "\/" (y ` )))) by ROBBINS3:def 6

      .= (y "/\" ((x ` ) "/\" (x "\/" (y ` )))) by ROBBINS3:def 6

      .= ((y "/\" (x ` )) "/\" (x "\/" (y ` ))) by LATTICES:def 7

      .= ((((y ` ) "\/" ((x ` ) ` )) ` ) "/\" (x "\/" (y ` ))) by ROBBINS1:def 23

      .= (((x "\/" (y ` )) ` ) "/\" (x "\/" (y ` ))) by ROBBINS3:def 6

      .= ( Bottom L) by Th2;

      then (((x "\/" ((x ` ) "/\" y)) ` ) ` ) = y by A4, A5;

      hence thesis by ROBBINS3:def 6;

    end;

    theorem :: ROBBINS4:33

    L is orthomodular iff for a,b be Element of L st a _|_ b & (a "\/" b) = ( Top L) holds a = (b ` )

    proof

      thus L is orthomodular implies for a,b be Element of L st a _|_ b & (a "\/" b) = ( Top L) holds a = (b ` )

      proof

        assume

         A1: L is orthomodular;

        let x,y be Element of L;

        assume x _|_ y;

        then

         A2: x [= (y ` );

        assume

         A3: (x "\/" y) = ( Top L);

        

        thus (y ` ) = (x "\/" ((x ` ) "/\" (y ` ))) by A1, A2

        .= (x "\/" ((((x ` ) ` ) "\/" ((y ` ) ` )) ` )) by ROBBINS1:def 23

        .= (x "\/" ((x "\/" ((y ` ) ` )) ` )) by ROBBINS3:def 6

        .= (x "\/" ((x "\/" y) ` )) by ROBBINS3:def 6

        .= (x "\/" ((((x ` ) ` ) "\/" (x ` )) ` )) by A3, Th2

        .= (x "\/" ((x ` ) "/\" x)) by ROBBINS1:def 23

        .= x by LATTICES:def 8;

      end;

      assume

       A4: for a,b be Element of L st a _|_ b & (a "\/" b) = ( Top L) holds a = (b ` );

      let x,y be Element of L;

      assume x [= y;

      then (x "\/" ((x ` ) "/\" y)) [= (y "\/" ((x ` ) "/\" y)) by FILTER_0: 1;

      then (x "\/" ((x ` ) "/\" y)) [= y by LATTICES:def 8;

      then (x "\/" ((x ` ) "/\" y)) [= ((y ` ) ` ) by ROBBINS3:def 6;

      then

       A5: (x "\/" ((x ` ) "/\" y)) _|_ (y ` );

      ((y ` ) "\/" (x "\/" ((x ` ) "/\" y))) = (((y ` ) "\/" x) "\/" ((x ` ) "/\" y)) by LATTICES:def 5

      .= (((y ` ) "\/" ((x ` ) ` )) "\/" ((x ` ) "/\" y)) by ROBBINS3:def 6

      .= (((((y ` ) "\/" ((x ` ) ` )) ` ) ` ) "\/" ((x ` ) "/\" y)) by ROBBINS3:def 6

      .= (((y "/\" (x ` )) ` ) "\/" ((x ` ) "/\" y)) by ROBBINS1:def 23

      .= ( Top L) by Th2;

      then (x "\/" ((x ` ) "/\" y)) = ((y ` ) ` ) by A4, A5;

      hence thesis by ROBBINS3:def 6;

    end;

    theorem :: ROBBINS4:34

    

     Th34: L is orthomodular iff for a,b be Element of L st b [= a holds (a "/\" ((a ` ) "\/" b)) = b

    proof

      thus L is orthomodular implies for a,b be Element of L st b [= a holds (a "/\" ((a ` ) "\/" b)) = b

      proof

        assume

         A1: L is orthomodular;

        let a,b be Element of L;

        assume b [= a;

        then (a ` ) [= (b ` ) by Th4;

        

        then (b ` ) = ((a ` ) "\/" (((a ` ) ` ) "/\" (b ` ))) by A1

        .= ((a ` ) "\/" (a "/\" (b ` ))) by ROBBINS3:def 6

        .= ((a ` ) "\/" (((a ` ) "\/" ((b ` ) ` )) ` )) by ROBBINS1:def 23

        .= ((a ` ) "\/" (((a ` ) "\/" b) ` )) by ROBBINS3:def 6

        .= ((((a ` ) "\/" (((a ` ) "\/" b) ` )) ` ) ` ) by ROBBINS3:def 6

        .= ((a "/\" ((a ` ) "\/" b)) ` ) by ROBBINS1:def 23;

        then ((b ` ) ` ) = (a "/\" ((a ` ) "\/" b)) by ROBBINS3:def 6;

        hence thesis by ROBBINS3:def 6;

      end;

      assume

       A2: for a,b be Element of L st b [= a holds (a "/\" ((a ` ) "\/" b)) = b;

      let a,b be Element of L;

      assume a [= b;

      then (b ` ) [= (a ` ) by Th4;

      

      then (b ` ) = ((a ` ) "/\" (((a ` ) ` ) "\/" (b ` ))) by A2

      .= ((a ` ) "/\" (((((a ` ) ` ) "\/" (b ` )) ` ) ` )) by ROBBINS3:def 6

      .= ((a ` ) "/\" (((a ` ) "/\" b) ` )) by ROBBINS1:def 23

      .= ((((a ` ) ` ) "\/" ((((a ` ) "/\" b) ` ) ` )) ` ) by ROBBINS1:def 23

      .= ((a "\/" ((((a ` ) "/\" b) ` ) ` )) ` ) by ROBBINS3:def 6

      .= ((a "\/" ((a ` ) "/\" b)) ` ) by ROBBINS3:def 6;

      then ((b ` ) ` ) = (a "\/" ((a ` ) "/\" b)) by ROBBINS3:def 6;

      hence b = (a "\/" ((a ` ) "/\" b)) by ROBBINS3:def 6;

    end;

    theorem :: ROBBINS4:35

    L is orthomodular iff for a, b holds (a "/\" ((a ` ) "\/" (a "/\" b))) = (a "/\" b)

    proof

      thus L is orthomodular implies for a, b holds (a "/\" ((a ` ) "\/" (a "/\" b))) = (a "/\" b) by LATTICES: 6, Th34;

      assume

       A1: for a, b holds (a "/\" ((a ` ) "\/" (a "/\" b))) = (a "/\" b);

      for a, b holds b [= a implies (a "/\" ((a ` ) "\/" b)) = b

      proof

        let a, b;

        assume

         A2: b [= a;

        

        hence b = (a "/\" b) by LATTICES: 4

        .= (a "/\" ((a ` ) "\/" (a "/\" b))) by A1

        .= (a "/\" ((a ` ) "\/" b)) by A2, LATTICES: 4;

      end;

      hence thesis by Th34;

    end;

    theorem :: ROBBINS4:36

    

     Th36: L is orthomodular iff for a,b be Element of L holds (a "\/" b) = (((a "\/" b) "/\" a) "\/" ((a "\/" b) "/\" (a ` )))

    proof

      thus L is orthomodular implies for a,b be Element of L holds (a "\/" b) = (((a "\/" b) "/\" a) "\/" ((a "\/" b) "/\" (a ` )))

      proof

        assume

         A1: L is orthomodular;

        let a,b be Element of L;

        (a "\/" b) = (a "\/" ((a "\/" b) "/\" (a ` ))) by A1, Th6;

        hence thesis by LATTICES:def 9;

      end;

      assume

       A2: for a,b be Element of L holds (a "\/" b) = (((a "\/" b) "/\" a) "\/" ((a "\/" b) "/\" (a ` )));

      let x,y be Element of L;

      assume

       A3: x [= y;

      

      hence y = (x "\/" y)

      .= (((x "\/" y) "/\" x) "\/" ((x "\/" y) "/\" (x ` ))) by A2

      .= ((y "/\" x) "\/" ((x "\/" y) "/\" (x ` ))) by A3

      .= ((y "/\" x) "\/" (y "/\" (x ` ))) by A3

      .= (x "\/" ((x ` ) "/\" y)) by A3, LATTICES: 4;

    end;

    theorem :: ROBBINS4:37

    L is orthomodular iff for a, b st a [= b holds ((a "\/" b) "/\" (b "\/" (a ` ))) = ((a "/\" b) "\/" (b "/\" (a ` )))

    proof

      thus L is orthomodular implies for a, b st a [= b holds ((a "\/" b) "/\" (b "\/" (a ` ))) = ((a "/\" b) "\/" (b "/\" (a ` )))

      proof

        assume

         A1: L is orthomodular;

        let a, b;

        assume

         A2: a [= b;

        (a "/\" b) [= (a "\/" b) & (b "/\" (a ` )) [= (a "\/" b) by FILTER_0: 3, LATTICES: 6;

        then

         A3: ((a "/\" b) "\/" (b "/\" (a ` ))) [= (a "\/" b) by FILTER_0: 6;

        (a "/\" b) [= (b "\/" (a ` )) & (b "/\" (a ` )) [= (b "\/" (a ` )) by FILTER_0: 3, LATTICES: 6;

        then ((a "/\" b) "\/" (b "/\" (a ` ))) [= (b "\/" (a ` )) by FILTER_0: 6;

        then

         A4: ((a "/\" b) "\/" (b "/\" (a ` ))) [= ((a "\/" b) "/\" (b "\/" (a ` ))) by A3, FILTER_0: 7;

        

         A5: ((a "\/" b) "/\" (b "\/" (a ` ))) [= (a "\/" b) by LATTICES: 6;

        (a "\/" b) = (((a "\/" b) "/\" a) "\/" ((a "\/" b) "/\" (a ` ))) by A1, Th36

        .= ((b "/\" a) "\/" ((a "\/" b) "/\" (a ` ))) by A2

        .= ((b "/\" a) "\/" (b "/\" (a ` ))) by A2;

        hence thesis by A4, A5, LATTICES: 8;

      end;

      assume

       A6: for a, b st a [= b holds ((a "\/" b) "/\" (b "\/" (a ` ))) = ((a "/\" b) "\/" (b "/\" (a ` )));

      let a, b;

      assume

       A7: a [= b;

      

      then ((a "\/" b) "/\" (b "\/" (a ` ))) = ((a "/\" b) "\/" (b "/\" (a ` ))) by A6

      .= (a "\/" ((a ` ) "/\" b)) by A7, LATTICES: 4;

      

      hence (a "\/" ((a ` ) "/\" b)) = (b "/\" (b "\/" (a ` ))) by A7

      .= b by LATTICES:def 9;

    end;

    ::$Notion-Name

    theorem :: ROBBINS4:38

    for L be non empty OrthoLattStr holds L is Orthomodular_Lattice iff (for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a)) & (for a,b,c be Element of L holds (a "\/" b) = (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` )))) & for a,b be Element of L holds a = (a "\/" (b "/\" (b ` )))

    proof

      let L be non empty OrthoLattStr;

      thus L is Orthomodular_Lattice implies (for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a)) & (for a,b,c be Element of L holds (a "\/" b) = (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` )))) & for a,b be Element of L holds a = (a "\/" (b "/\" (b ` )))

      proof

        assume

         A1: L is Orthomodular_Lattice;

        hence for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a) by Th3;

        thus for a,b,c be Element of L holds (a "\/" b) = (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` )))

        proof

          let a,b,c be Element of L;

          ((a "\/" b) "/\" (a ` )) [= (a "\/" b) & ((a "\/" b) "/\" (a "\/" c)) [= (a "\/" b) by A1, LATTICES: 6;

          then

           A2: (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` ))) [= (a "\/" b) by A1, FILTER_0: 6;

          (a "/\" (a "\/" b)) [= ((a "\/" c) "/\" (a "\/" b)) by A1, LATTICES: 5, LATTICES: 9;

          then ((a "\/" b) "/\" a) [= ((a "\/" c) "/\" (a "\/" b)) by A1, LATTICES:def 6;

          then ((a "\/" b) "/\" a) [= ((a "\/" b) "/\" (a "\/" c)) by A1, LATTICES:def 6;

          then (((a "\/" b) "/\" (a ` )) "\/" ((a "\/" b) "/\" a)) [= (((a "\/" b) "/\" (a ` )) "\/" ((a "\/" b) "/\" (a "\/" c))) by A1, FILTER_0: 1;

          then

           A3: (((a "\/" b) "/\" a) "\/" ((a "\/" b) "/\" (a ` ))) [= (((a "\/" b) "/\" (a ` )) "\/" ((a "\/" b) "/\" (a "\/" c))) by A1, LATTICES:def 4;

          (a "\/" b) = (((a "\/" b) "/\" a) "\/" ((a "\/" b) "/\" (a ` ))) by A1, Th36;

          then (a "\/" b) [= (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` ))) by A1, A3, LATTICES:def 4;

          hence thesis by A1, A2, LATTICES: 8;

        end;

        thus thesis by A1, Th3;

      end;

      assume

       A4: for a,b,c be Element of L holds ((a "\/" b) "\/" c) = ((((c ` ) "/\" (b ` )) ` ) "\/" a);

      assume

       A5: for a,b,c be Element of L holds (a "\/" b) = (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` )));

      assume

       A6: for a,b be Element of L holds a = (a "\/" (b "/\" (b ` )));

      

       A7: for a,b be Element of L holds (a "\/" b) = (((a "\/" b) "/\" a) "\/" ((a "\/" b) "/\" (a ` )))

      proof

        let a,b be Element of L;

        set c = (a "/\" (a ` ));

        (a "\/" b) = (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` ))) by A5;

        hence thesis by A6;

      end;

      for a,c be Element of L holds a = (a "/\" (a "\/" c))

      proof

        let a,c be Element of L;

        set b = (a "/\" (a ` ));

        

        thus a = (a "\/" b) by A6

        .= (((a "\/" b) "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` ))) by A5

        .= ((a "/\" (a "\/" c)) "\/" ((a "\/" b) "/\" (a ` ))) by A6

        .= ((a "/\" (a "\/" c)) "\/" (a "/\" (a ` ))) by A6

        .= (a "/\" (a "\/" c)) by A6;

      end;

      then L is Ortholattice by A4, A6, Th3;

      hence thesis by A7, Th36;

    end;

    reserve L for join-Associative meet-Absorbing de_Morgan orthomodular Lattice-like non empty OrthoLattStr;

    reserve v0,v1,v2,v64,v65 for Element of L;

    registration

      cluster -> with_Top for join-Associative meet-Absorbing de_Morgan orthomodular Lattice-like non empty OrthoLattStr;

      coherence

      proof

        let L;

        deffunc c( Element of L) = ($1 ` );

        for x,y be Element of L holds (x "\/" c(x)) = (y "\/" c(y))

        proof

          

           A1: (v0 "\/" c("\/")) = v0

          proof

            (v0 "/\" v1) = c("\/") by ROBBINS1:def 23;

            hence thesis by ROBBINS3:def 3;

          end;

          

           A2: (v64 "\/" c(c)) = v64

          proof

            now

              let v64, v1;

              ( c(v64) "\/" c("\/")) = c(v64) by A1;

              hence (v64 "\/" c(c)) = v64 by A1;

            end;

            hence thesis;

          end;

          

           A3: (v0 "\/" c("\/")) = (v0 "\/" v1)

          proof

            ( c(v0) "/\" (v0 "\/" v1)) = c("\/") by ROBBINS1:def 23;

            hence thesis by Def2;

          end;

          

           A4: (v64 "\/" c("\/")) = v64

          proof

            ( c(v64) "\/" c("\/")) = ( c(v64) "\/" v1) by A3;

            hence thesis by A1;

          end;

          

           A5: (v64 "\/" v65) = (v65 "\/" (v64 "\/" c("\/")))

          proof

            (v65 "\/" c("\/")) = v65 by A4;

            hence thesis by ROBBINS3:def 1;

          end;

          

           A6: (v64 "\/" v65) = (v65 "\/" (v64 "\/" c(c)))

          proof

            (v65 "\/" c(c)) = v65 by A2;

            hence thesis by ROBBINS3:def 1;

          end;

          

           A7: (v64 "\/" ((v64 ` ) ` )) = (((((v64 ` ) ` ) ` ) ` ) "\/" v64)

          proof

            (((((v64 ` ) ` ) ` ) ` ) "\/" ((v64 ` ) ` )) = ((v64 ` ) ` ) by A2;

            hence thesis by A6;

          end;

          

           A8: v64 = (((((v64 ` ) ` ) ` ) ` ) "\/" v64)

          proof

            (v64 "\/" ((v64 ` ) ` )) = v64 by A2;

            hence thesis by A7;

          end;

          

           A9: ((((v65 ` ) ` ) ` ) "\/" (v65 ` )) = (((v65 ` ) ` ) ` )

          proof

            (((((v65 ` ) ` ) ` ) ` ) "\/" v65) = v65 by A8;

            hence thesis by A4;

          end;

          

           A10: (v65 ` ) = (((v65 ` ) ` ) ` )

          proof

            ((((v65 ` ) ` ) ` ) "\/" (v65 ` )) = (v65 ` ) by A2;

            hence thesis by A9;

          end;

          

           A11: ( c(c) "\/" c("\/")) = ( c(c) "\/" v65)

          proof

            ( c(c) "\/" v65) = v65 by A8;

            hence thesis by A3;

          end;

          

           A12: ( c(c) "\/" c("\/")) = ( c(c) "\/" v65)

          proof

            (((v65 ` ) ` ) ` ) = (v65 ` ) by A10;

            hence thesis by A11;

          end;

          

           A13: ( c(c) "\/" c("\/")) = ( c(c) "\/" v65)

          proof

            (((v65 ` ) ` ) ` ) = (v65 ` ) by A10;

            hence thesis by A12;

          end;

          

           A14: ( c(c) "\/" c("\/")) = ( c(c) "\/" v65)

          proof

            (((v65 ` ) ` ) ` ) = (v65 ` ) by A10;

            hence thesis by A13;

          end;

          

           A15: ( c(c) "\/" c("\/")) = ( c(c) "\/" v65)

          proof

            (((v65 ` ) ` ) ` ) = (v65 ` ) by A10;

            hence thesis by A14;

          end;

          

           A16: ( c(c) "\/" c("\/")) = v65

          proof

            (((v65 ` ) ` ) "\/" v65) = v65 by A2;

            hence thesis by A15;

          end;

          

           A17: ( c(c) "\/" c("\/")) = ((v0 ` ) ` )

          proof

            (((v0 ` ) ` ) ` ) = (v0 ` ) by A10;

            hence thesis by A4;

          end;

          

           A18: ((v0 ` ) ` ) = v0

          proof

            ( c(c) "\/" c("\/")) = ((v0 ` ) ` ) by A17;

            hence thesis by A16;

          end;

          

           A19: (v64 "\/" c("\/")) = (v64 "\/" (v1 "\/" c(c)))

          proof

            (v64 "\/" (v1 "\/" c(c))) = (v1 "\/" v64) by A6;

            hence thesis by A3;

          end;

          

           A20: (v64 "\/" c("\/")) = (v1 "\/" v64)

          proof

            (v64 "\/" (v1 "\/" ((v64 ` ) ` ))) = (v1 "\/" v64) by A6;

            hence thesis by A19;

          end;

          

           A21: (v0 "\/" c("\/")) = (v1 "\/" v0)

          proof

            ((v0 ` ) ` ) = v0 by A18;

            hence thesis by A20;

          end;

          

           A22: (v64 "\/" (v1 "\/" c(v64))) = ( c(v64) "\/" v64)

          proof

            ( c(v64) "\/" c("\/")) = (v1 "\/" c(v64)) by A21;

            hence thesis by A5;

          end;

          

           A23: ( c(v0) "\/" c("\/")) = (v0 ` )

          proof

            ((v0 ` ) ` ) = v0 by A18;

            hence thesis by A4;

          end;

          

           A24: ((v0 "\/" v1) "\/" c(v0)) = ( c("\/") "\/" (v0 "\/" v1))

          proof

            ((v0 ` ) "\/" c("\/")) = c(v0) by A23;

            hence thesis by A22;

          end;

          

           A25: (v0 "\/" (v1 "\/" c(v0))) = ( c("\/") "\/" (v0 "\/" v1))

          proof

            ((v0 "\/" v1) "\/" c(v0)) = (v0 "\/" (v1 "\/" c(v0))) by ROBBINS3:def 1;

            hence thesis by A24;

          end;

          

           A26: (v0 "\/" (v1 "\/" (v65 "\/" c("\/")))) = ( c("\/") "\/" (v0 "\/" v1))

          proof

            ((v0 "\/" v1) "\/" (v65 "\/" c("\/"))) = (v0 "\/" (v1 "\/" (v65 "\/" c("\/")))) by ROBBINS3:def 1;

            hence thesis by A22;

          end;

          

           A27: (v0 "\/" (v1 "\/" (v65 "\/" c("\/")))) = (v0 "\/" (v1 "\/" c(v0)))

          proof

            ( c("\/") "\/" (v0 "\/" v1)) = (v0 "\/" (v1 "\/" c(v0))) by A25;

            hence thesis by A26;

          end;

          

           A28: ( c("\/") "\/" (v0 "\/" v1)) = (v0 "\/" (v1 "\/" (v65 "\/" c("\/"))))

          proof

            ((v0 "\/" v1) "\/" (v65 "\/" c("\/"))) = (v0 "\/" (v1 "\/" (v65 "\/" c("\/")))) by ROBBINS3:def 1;

            hence thesis by A22;

          end;

          

           A29: ( c("\/") "\/" (v0 "\/" v1)) = (v0 "\/" (v1 "\/" c(v0)))

          proof

            now

              let v65, v1, v0;

              (v0 "\/" (v1 "\/" (v65 "\/" c("\/")))) = (v0 "\/" (v1 "\/" c(v0))) by A27;

              hence ( c("\/") "\/" (v0 "\/" v1)) = (v0 "\/" (v1 "\/" c(v0))) by A28;

            end;

            hence thesis;

          end;

          

           A30: (v2 "\/" (v1 "\/" c(v2))) = ((v1 "\/" v2) "\/" (v65 "\/" c("\/")))

          proof

            ( c("\/") "\/" (v2 "\/" v1)) = (v2 "\/" (v1 "\/" c(v2))) by A29;

            hence thesis by A22;

          end;

          

           A31: (v2 "\/" (v1 "\/" (v2 ` ))) = (v1 "\/" (v2 "\/" (v65 "\/" c("\/"))))

          proof

            ((v1 "\/" v2) "\/" (v65 "\/" c("\/"))) = (v1 "\/" (v2 "\/" (v65 "\/" c("\/")))) by ROBBINS3:def 1;

            hence thesis by A30;

          end;

          

           A32: (v2 "\/" (v1 "\/" (v2 ` ))) = (v1 "\/" (v2 "\/" (v1 ` )))

          proof

            now

              let v65, v2, v1;

              (v1 "\/" (v2 "\/" (v65 "\/" c("\/")))) = (v1 "\/" (v2 "\/" c(v1))) by A27;

              hence (v2 "\/" (v1 "\/" c(v2))) = (v1 "\/" (v2 "\/" c(v1))) by A31;

            end;

            hence thesis;

          end;

          

           A33: (v0 "\/" (v0 ` )) = (v1 "\/" (v0 "\/" (v1 ` )))

          proof

            (v0 "\/" (v1 "\/" (v0 ` ))) = (v0 "\/" (v0 ` )) by A22;

            hence thesis by A32;

          end;

          let v1, v0;

          (v1 "\/" (v0 "\/" (v1 ` ))) = (v1 "\/" (v1 ` )) by A22;

          hence thesis by A33;

        end;

        hence thesis;

      end;

    end

    theorem :: ROBBINS4:39

    for L be non empty OrthoLattStr holds L is Orthomodular_Lattice iff L is join-Associative meet-Absorbing de_Morgan Orthomodular

    proof

      let L be non empty OrthoLattStr;

      thus L is Orthomodular_Lattice implies L is join-Associative meet-Absorbing de_Morgan Orthomodular;

      assume

       A1: L is join-Associative;

      assume

       A2: L is meet-Absorbing;

      assume

       A3: L is de_Morgan;

      

       A4: for x,y be Element of L holds x = (x "\/" (((x ` ) "\/" (y ` )) ` ))

      proof

        let x,y be Element of L;

        

        thus x = (x "\/" (x "/\" y)) by A2

        .= (x "\/" (((x ` ) "\/" (y ` )) ` )) by A3;

      end;

      

       A5: for x be Element of L holds x = (x "\/" ((x ` ) ` ))

      proof

        let x be Element of L;

        

        thus x = (x "\/" (((x ` ) "\/" ((((x ` ) ` ) "\/" ((x ` ) ` )) ` )) ` )) by A4

        .= (x "\/" (((x ` ) "\/" ((x ` ) "/\" (x ` ))) ` )) by A3

        .= (x "\/" ((x ` ) ` )) by A2;

      end;

      assume

       A6: L is Orthomodular;

      

       A7: for x,y be Element of L holds (x "\/" y) = (x "\/" ((((x ` ) ` ) "\/" ((x "\/" y) ` )) ` ))

      proof

        let x,y be Element of L;

        

        thus (x "\/" y) = (x "\/" ((x ` ) "/\" (x "\/" y))) by A6

        .= (x "\/" ((((x ` ) ` ) "\/" ((x "\/" y) ` )) ` )) by A3;

      end;

      

       A8: for x,y be Element of L holds (x "\/" (((x ` ) "\/" y) ` )) = x

      proof

        let x,y be Element of L;

        

        thus (x "\/" (((x ` ) "\/" y) ` )) = (x "\/" (((x ` ) "\/" (((((x ` ) ` ) ` ) "\/" (((x ` ) "\/" y) ` )) ` )) ` )) by A7

        .= x by A4;

      end;

      

       A9: for x,y be Element of L holds (x "\/" (y "\/" ((x ` ) ` ))) = (y "\/" x)

      proof

        let x,y be Element of L;

        (y "\/" x) = (y "\/" (x "\/" ((x ` ) ` ))) by A5;

        hence thesis by A1;

      end;

      

       A10: for x,y be Element of L holds (x "\/" ((y "\/" (x ` )) ` )) = x

      proof

        let x,y be Element of L;

        

        thus (x "\/" ((y "\/" (x ` )) ` )) = (x "\/" (((x ` ) "\/" (y "\/" (((x ` ) ` ) ` ))) ` )) by A9

        .= x by A8;

      end;

      

       A11: for x be Element of L holds ((x ` ) "\/" (x ` )) = (x ` )

      proof

        let x be Element of L;

        

        thus (x ` ) = ((x ` ) "\/" ((x "\/" ((x ` ) ` )) ` )) by A10

        .= ((x ` ) "\/" (x ` )) by A5;

      end;

      

       A12: for x be Element of L holds (((x ` ) ` ) "\/" x) = x

      proof

        let x be Element of L;

        (((x ` ) ` ) "\/" x) = (x "\/" (((x ` ) ` ) "\/" ((x ` ) ` ))) by A9

        .= (x "\/" ((x ` ) ` )) by A11;

        hence thesis by A5;

      end;

      

       A13: for x be Element of L holds (((((x ` ) ` ) ` ) ` ) "\/" x) = x

      proof

        let x be Element of L;

        (((((x ` ) ` ) ` ) ` ) "\/" x) = (x "\/" (((((x ` ) ` ) ` ) ` ) "\/" ((x ` ) ` ))) by A9

        .= (x "\/" ((x ` ) ` )) by A12;

        hence thesis by A5;

      end;

      

       A14: for x be Element of L holds (((x ` ) ` ) ` ) = (x ` )

      proof

        let x be Element of L;

        (((x ` ) ` ) ` ) = ((((x ` ) ` ) ` ) "\/" ((((((x ` ) ` ) ` ) ` ) "\/" x) ` )) by A8

        .= ((((x ` ) ` ) ` ) "\/" (x ` )) by A13;

        hence thesis by A12;

      end;

      

       A15: for x,y be Element of L holds (((x ` ) ` ) "\/" ((y "\/" (x ` )) ` )) = ((x ` ) ` )

      proof

        let x,y be Element of L;

        ((x ` ) ` ) = (((x ` ) ` ) "\/" ((y "\/" (((x ` ) ` ) ` )) ` )) by A10;

        hence thesis by A14;

      end;

      

       A16: for x be Element of L holds (((x ` ) ` ) "\/" ((((x ` ) ` ) "\/" (x ` )) ` )) = x

      proof

        let x be Element of L;

        x = (((((x ` ) ` ) ` ) ` ) "\/" x) by A13

        .= (((((x ` ) ` ) ` ) ` ) "\/" ((((((((x ` ) ` ) ` ) ` ) ` ) ` ) "\/" ((((((x ` ) ` ) ` ) ` ) "\/" x) ` )) ` )) by A7

        .= (((((x ` ) ` ) ` ) ` ) "\/" ((((((((x ` ) ` ) ` ) ` ) ` ) ` ) "\/" (x ` )) ` )) by A13

        .= (((x ` ) ` ) "\/" ((((((((x ` ) ` ) ` ) ` ) ` ) ` ) "\/" (x ` )) ` )) by A14

        .= (((x ` ) ` ) "\/" ((((((x ` ) ` ) ` ) ` ) "\/" (x ` )) ` )) by A14;

        hence thesis by A14;

      end;

      

       A17: for x be Element of L holds ((x ` ) ` ) = x

      proof

        let x be Element of L;

        

        thus x = (((x ` ) ` ) "\/" ((((x ` ) ` ) "\/" (x ` )) ` )) by A16

        .= ((x ` ) ` ) by A15;

      end;

      

       A18: L is join-absorbing

      proof

        let a,b be Element of L;

        (a "/\" (a "\/" b)) = (((a ` ) "\/" ((a "\/" b) ` )) ` ) by A3

        .= (((a ` ) "\/" ((((a ` ) ` ) "\/" b) ` )) ` ) by A17

        .= ((a ` ) ` ) by A8

        .= a by A17;

        hence thesis;

      end;

      L is meet-Associative

      proof

        let a,b,c be Element of L;

        

        thus (a "/\" (b "/\" c)) = (a "/\" (((b ` ) "\/" (c ` )) ` )) by A3

        .= (((a ` ) "\/" ((((b ` ) "\/" (c ` )) ` ) ` )) ` ) by A3

        .= (((a ` ) "\/" ((b ` ) "\/" (c ` ))) ` ) by A17

        .= (((b ` ) "\/" ((a ` ) "\/" (c ` ))) ` ) by A1

        .= (((b ` ) "\/" ((((a ` ) "\/" (c ` )) ` ) ` )) ` ) by A17

        .= (((b ` ) "\/" ((a "/\" c) ` )) ` ) by A3

        .= (b "/\" (a "/\" c)) by A3;

      end;

      then

      reconsider L9 = L as Lattice-like non empty OrthoLattStr by A1, A2, A18;

      reconsider L9 as join-Associative meet-Absorbing de_Morgan Orthomodular Lattice-like non empty OrthoLattStr by A3, A6;

      L9 is with_Top;

      hence thesis by A17, ROBBINS3:def 6;

    end;