The Mizar article:

On the Characterization of Modular and Distributive Lattices

by
Adam Naumowicz

Received April 3, 1998

Copyright (c) 1998 Association of Mizar Users

MML identifier: YELLOW11
[ MML identifier index ]


environ

 vocabulary ORDINAL1, BOOLE, RELAT_2, LATTICE3, ORDERS_1, LATTICES, WAYBEL_0,
      YELLOW_1, CAT_1, FILTER_2, WELLORD1, PRE_TOPC, YELLOW_0, FUNCT_1, SEQM_3,
      RELAT_1, ORDINAL2, MEASURE5, QUANTAL1, FINSET_1, BHSP_3, YELLOW11;
 notation TARSKI, XBOOLE_0, ENUMSET1, SUBSET_1, RELAT_1, FUNCT_1, FUNCT_2,
      PRE_TOPC, STRUCT_0, ORDERS_1, LATTICE3, ORDERS_3, YELLOW_0, YELLOW_1,
      YELLOW_2, WAYBEL_1, LATTICE5, FINSET_1, GROUP_1, WAYBEL_0, ORDINAL1;
 constructors LATTICE3, GROUP_1, ORDERS_3, WAYBEL_1, ENUMSET1;
 clusters STRUCT_0, LATTICE3, YELLOW_0, ORDERS_1, FINSET_1, YELLOW_1, RELSET_1,
      XBOOLE_0;
 requirements NUMERALS, REAL, SUBSET, BOOLE;
 definitions TARSKI, YELLOW_0, WAYBEL_1, FUNCT_1, WAYBEL_0, LATTICE3, XBOOLE_0;
 theorems WAYBEL_1, YELLOW_0, YELLOW_3, YELLOW_5, LATTICE3, STRUCT_0, TARSKI,
      FUNCT_2, WAYBEL_0, ZFMISC_1, FUNCT_1, ORDERS_1, YELLOW_1, ENUMSET1,
      CARD_1, GROUP_1, FINSET_1, CARD_5, ORDINAL1, XBOOLE_0, XBOOLE_1;
 schemes FUNCT_2, FINSET_1, XBOOLE_0;

begin

reserve x for set;

:: Preliminaries

theorem Th1:
 3 = {0,1,2}
  proof
   thus 3 = succ 2
         .= {0,1} \/ {2} by CARD_5:1,ORDINAL1:def 1
         .= {0,1,2} by ENUMSET1:43;
  end;

theorem Th2:
 2\1={1}
  proof
   thus 2\1 c= {1}
    proof
     let x be set;
     assume x in 2\1;
     then x in {0,1} & not x in {0} by CARD_5:1,XBOOLE_0:def 4;
     then (x=0 or x=1) & x <> 0 by TARSKI:def 1,def 2;
     hence thesis by TARSKI:def 1;
    end;
   let x be set;
   assume x in {1};
   then x = 1 by TARSKI:def 1;
   then x in {0,1} & not x in {0} by TARSKI:def 1,def 2;
   hence thesis by CARD_5:1,XBOOLE_0:def 4;
  end;

theorem Th3:
 3\1 = {1,2}
  proof
   thus 3\1 c= {1,2}
    proof
     let x;
     assume x in 3\1;
     then x in {0,1,2} & not x in {0} by Th1,CARD_5:1,XBOOLE_0:def 4;
     then (x=0 or x=1 or x=2) & x <> 0 by ENUMSET1:13,TARSKI:def 1;
     hence x in {1,2} by TARSKI:def 2;
    end;
   thus {1,2} c= 3\1
    proof
     let x;
     assume x in {1,2};
     then x=1 or x=2 by TARSKI:def 2;
     then x in {0,1,2} & not x in {0} by ENUMSET1:14,TARSKI:def 1;
     hence x in 3\1 by Th1,CARD_5:1,XBOOLE_0:def 4;
    end;
  end;

theorem Th4:
 3\2 = {2}
  proof
   thus 3\2 c= {2}
    proof
     let x;
     assume x in 3\2;
     then x in {0,1,2} & not x in {0,1} by Th1,CARD_5:1,XBOOLE_0:def 4;
     then (x=0 or x=1 or x=2) & (x <> 0 & x <> 1)
       by ENUMSET1:13,TARSKI:def 2;
     hence x in {2} by TARSKI:def 1;
    end;
   thus {2} c= 3\2
    proof
     let x;
     assume x in {2};
     then x=2 by TARSKI:def 1;
     then x in {0,1,2} & not x in {0,1} by ENUMSET1:14,TARSKI:def 2;
     hence x in 3\2 by Th1,CARD_5:1,XBOOLE_0:def 4;
    end;
  end;

Lm1:
 3\2 c= 3\1
  proof
   let x be set;
   assume x in 3\2;
   then x=2 by Th4,TARSKI:def 1;
   hence x in 3\1 by Th3,TARSKI:def 2;
  end;

begin:: Main part

theorem Th5:
 for L being antisymmetric reflexive with_infima with_suprema RelStr
 for a,b being Element of L holds a"/\"b = b iff a"\/"b = a
  proof
   let L be antisymmetric reflexive with_infima with_suprema RelStr;
   let a,b be Element of L;
   thus a"/\"b = b implies a"\/"b = a
    proof
     assume a"/\"b = b;
     then b <= a by YELLOW_0:23;
     hence a"\/"b = a by YELLOW_0:24;
    end;
    assume a"\/"b = a;
    then b <= a by YELLOW_0:22;
    hence a"/\"b = b by YELLOW_0:25;
  end;

theorem Th6:
 for L being LATTICE
 for a,b,c being Element of L holds (a"/\"b)"\/"(a"/\"c) <= a"/\"(b"\/"c)
  proof
   let L be LATTICE;
   let a,b,c be Element of L;
     b <= b"\/"c & c <= b"\/"c & a <= a by YELLOW_0:22;
   then a"/\"b <= a"/\"(b"\/"c) & a"/\"c <= a"/\"(b"\/"c) by YELLOW_3:2;
   hence thesis by YELLOW_5:9;
  end;

theorem Th7:
 for L being LATTICE
 for a,b,c being Element of L holds a"\/"(b"/\"c) <= (a"\/"b)"/\"(a"\/"c)
  proof
   let L be LATTICE;
   let a,b,c be Element of L;
     b"/\"c <= b & b"/\"c <= c & a <= a by YELLOW_0:23;
   then a"\/"(b"/\"c) <= a"\/"b & a"\/"(b"/\"c) <= a"\/"c by YELLOW_3:3;
   hence thesis by YELLOW_0:23;
  end;

theorem Th8:
 for L being LATTICE
 for a,b,c being Element of L holds a <= c implies a"\/"(b"/\"c) <= (a"\/"b)
"/\"c
  proof
   let L be LATTICE;
   let a,b,c be Element of L;
   assume
A1: a <= c;
A2: b"/\"c <= c & b"/\"c <= b & a <= a by YELLOW_0:23;
then A3: a"\/"(b"/\"c) <= c by A1,YELLOW_0:22;
     a"\/"(b"/\"c) <= a"\/"b by A2,YELLOW_3:3;
   hence thesis by A3,YELLOW_0:23;
  end;

definition
 func N_5 -> RelStr equals :Def1:
 InclPoset {0, 3 \ 1, 2, 3 \ 2, 3};
correctness;
end;

definition
 cluster N_5 -> strict reflexive transitive antisymmetric;
correctness by Def1;
 cluster N_5 -> with_infima with_suprema;
correctness
 proof
  set Z = {0, 3 \ 1, 2, 3 \ 2, 3};
  set N = InclPoset Z;
A1: Z <> {} by ENUMSET1:24;
A2:     N is with_suprema
         proof
            now
           let x,y be set;
           assume x in Z & y in Z;
then A3:     (x=0 or x=3\1 or x=2 or x=3\2 or x=3) &
           (y=0 or y=3\1 or y=2 or y=3\2 or y=3) by ENUMSET1:23;
A4:           (3\1) \/ 2 = {0,1,1,2} by Th3,CARD_5:1,ENUMSET1:45
                    .= {1,1,0,2} by ENUMSET1:110
                    .= {1,0,2} by ENUMSET1:71
                    .= {0,1,2} by ENUMSET1:99;
A5:           (3\1) \/ (3\2) = {1,2} by Th3,Th4,ZFMISC_1:14;
             3\1 c= 3 by XBOOLE_1:36;
then A6:           (3\1) \/ 3 = 3 by XBOOLE_1:12;
A7:           2 \/ (3\2) = 2 \/ 3 & 2 c= 3 by CARD_1:56,XBOOLE_1:39;
then A8:           2 \/ 3 = 3 by XBOOLE_1:12;
             3\2 c= 3 by XBOOLE_1:36;
           then (3\2) \/ 3 = 3 by XBOOLE_1:12;
           hence x \/ y in Z by A3,A4,A5,A6,A7,A8,Th1,Th3,ENUMSET1:24;
          end;
          hence thesis by A1,YELLOW_1:11;
         end;
          N is with_infima
         proof
          let x,y be Element of N;
A9:          Z = the carrier of N by YELLOW_1:1;
          thus ex z being Element of N st z <= x & z <= y &
          for z' being Element of N st z' <= x & z' <= y holds z' <= z
          proof
           per cases by A1,A9,ENUMSET1:23;
           suppose
         x = 0 & y = 0;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
         x = 0 & y = 3\1;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose x = 0 & y = 2;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose x = 0 & y = 3\2;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose x = 0 & y = 3;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose x = 3\1 & y = 0;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
         x = 3\1 & y = 3\1;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
A10:        x = 3\1 & y = 2;
             0 in Z by ENUMSET1:24;
           then 0 in the carrier of N by YELLOW_1:1;
           then reconsider z = 0 as Element of N;
           take z;
             z c= x & z c= y by XBOOLE_1:2;
           hence z <= x & z <= y by A1,YELLOW_1:3;
           let z' be Element of N;
             z' is Element of Z by YELLOW_1:1;
then A11:     z'=0 or z'=3\1 or z'=2 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
           assume z' <= x & z' <= y;
then A12:        z' c= 3\1 & z' c= 2 by A1,A10,YELLOW_1:3;
A13:       now
            assume z'= 3\1;
            then 2 in z' & not 2 in 2 by Th3,TARSKI:def 2;
            hence contradiction by A12;
           end;
A14:        now
            assume
            z'= 2;
            then 0 in z' & not 0 in 3\1 by Th3,CARD_5:1,TARSKI:def 2;
            hence contradiction by A12;
           end;
A15:       now
            assume z'= 3\2;
            then 2 in z' & not 2 in 2 by Th4,TARSKI:def 1;
            hence contradiction by A12;
           end;
             now
            assume z'= 3;
            then 2 in z' & not 2 in 2 by Th1,ENUMSET1:14;
            hence contradiction by A12;
           end;
           hence z' <= z by A1,A11,A13,A14,A15,YELLOW_1:3;

           suppose
A16:        x = 3\1 & y = 3\2;
             (3\1) /\ (3\2) = {2} by Th3,Th4,ZFMISC_1:19;
           then x /\ y in Z by A16,Th4,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
A17:       x = 3\1 & y = 3;
             (3\1) /\ 3 = (3 /\ 3) \ 1 by XBOOLE_1:49
                    .= 3\1;
           then x /\ y in Z by A17,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose x = 2 & y = 0;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
A18:       x = 2 & y = 3\1;
             0 in Z by ENUMSET1:24;
           then 0 in the carrier of N by YELLOW_1:1;
           then reconsider z = 0 as Element of N;
           take z;
             z c= x & z c= y by XBOOLE_1:2;
           hence z <= x & z <= y by A1,YELLOW_1:3;
           let z' be Element of N;
             z' is Element of Z by YELLOW_1:1;
then A19:     z'=0 or z'=3\1 or z'=2 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
           assume z' <= x & z' <= y;
then A20:        z' c= 3\1 & z' c= 2 by A1,A18,YELLOW_1:3;
A21:       now
            assume z'= 3\1;
            then 2 in z' & not 2 in 2 by Th3,TARSKI:def 2;
            hence contradiction by A20;
           end;
A22:        now
            assume
            z'= 2;
            then 0 in z' & not 0 in 3\1 by Th3,CARD_5:1,TARSKI:def 2;
            hence contradiction by A20;
           end;
A23:       now
            assume z'= 3\2;
            then 2 in z' & not 2 in 2 by Th4,TARSKI:def 1;
            hence contradiction by A20;
           end;
             now
            assume z'= 3;
            then 2 in z' & not 2 in 2 by Th1,ENUMSET1:14;
            hence contradiction by A20;
           end;
           hence z' <= z by A1,A19,A21,A22,A23,YELLOW_1:3;

           suppose
        x = 2 & y = 2;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
A24:       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 A24,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
A25:       x = 2 & y = 3;
             2 c= 3 by CARD_1:56;
           then 2 /\ 3 = 2 by XBOOLE_1:28;
           then x /\ y in Z by A25,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose x = 3\2 & y = 0;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
           suppose
A26:       x = 3\2 & y = 3\1;
             (3\1) /\ (3\2) = {2} by Th3,Th4,ZFMISC_1:19;
           then x /\ y in Z by A26,Th4,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
           suppose
A27:       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 A27,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
           suppose
        x = 3\2 & y = 3\2;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose
A28:       x = 3\2 & y = 3;
             (3\2) /\ 3 = (3 /\ 3) \2 by XBOOLE_1:49
                    .= 3\2;
           then x /\ y in Z by A28,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;

           suppose x = 3 & y = 0;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
           suppose
A29:       x = 3 & y = 3\1;
             (3\1) /\ 3 = (3 /\ 3) \ 1 by XBOOLE_1:49
                    .= 3\1;
           then x /\ y in Z by A29,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
           suppose
A30:       x = 3 & y = 2;
             2 c= 3 by CARD_1:56;
           then 2 /\ 3 = 2 by XBOOLE_1:28;
           then x /\ y in Z by A30,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
           suppose
A31:       x = 3 & y = 3\2;
             (3\2) /\ 3 = (3 /\ 3) \2 by XBOOLE_1:49
                    .= 3\2;
           then x /\ y in Z by A31,ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
           suppose
        x = 3 & y = 3;
           then x /\ y in Z by ENUMSET1:24;
           then x /\ y in the carrier of N by YELLOW_1:1;
           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 A1,YELLOW_1:3;
           let w be Element of N;
           assume w <= x & w <= y;
           then w c= x & w c= y by A1,YELLOW_1:3;
           then w c= x /\ y by XBOOLE_1:19;
           hence thesis by A1,YELLOW_1:3;
          end;
         end;
        hence thesis by A2,Def1;
       end;
end;

definition
 func M_3 -> RelStr equals :Def2:
 InclPoset{ 0, 1, 2 \ 1, 3 \ 2, 3 };
 correctness;
end;

definition
 cluster M_3 -> strict reflexive transitive antisymmetric;
correctness by Def2;
 cluster M_3 -> with_infima with_suprema;
correctness
 proof
  set Z = { 0, 1, 2 \ 1, 3 \ 2, 3 };
  set N = InclPoset Z;
A1: Z <> {} by ENUMSET1:24;
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 being Element of N st x <= z & y <= z &
        for z' being Element of N st x <= z' & y <= z' holds z <= z'
    proof
     per cases by A1,A3,ENUMSET1:23;
     suppose
    x=0 & y=0;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=0 & y=1;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=0 & y=2\1;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=0 & y=3\2;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=0 & y=3;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=1 & y=0;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
    x=1 & y=1;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A4:   x=1 & y=2\1;
       3 in Z by ENUMSET1:24;
     then 3 in the carrier of N by YELLOW_1:1;
     then reconsider z = 3 as Element of N;
     take z;
       x c= z & y c= z
      proof
       thus x c= z
        proof
         let X be set;
         assume X in x; then X=0 by A4,CARD_5:1,TARSKI:def 1;
         hence X in z by Th1,ENUMSET1:14;
        end;
        let X be set;
        assume X in y; then X=1 by A4,Th2,TARSKI:def 1;
        hence X in z by Th1,ENUMSET1:14;
      end;
     hence x <= z & y <= z by A1,YELLOW_1:3;
     let z' be Element of N;
       z' is Element of Z by YELLOW_1:1;
     then A5: z'=0 or z'=1 or z'=2\1 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
     assume x <= z' & y <= z';
     then A6:  1 c= z' & 2\1 c= z' by A1,A4,YELLOW_1:3;
A7:  now
      assume A8: z'= 0;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A6,A8;
     end;
A9:  now
      assume A10: z'= 1;
        1 in 2\1 by Th2,TARSKI:def 1;
      then 1 in z' by A6;
      hence contradiction by A10;
     end;
A11: now
      assume A12: z'= 2\1;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A6,A12,Th2,TARSKI:def 1;
     end;
       now
      assume A13: z'= 3\2;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A6,A13,Th4,TARSKI:def 1;
     end;
     hence z <= z' by A1,A5,A7,A9,A11,YELLOW_1:3;

     suppose
A14:   x=1 & y=3\2;
       3 in Z by ENUMSET1:24;
     then 3 in the carrier of N by YELLOW_1:1;
     then reconsider z = 3 as Element of N;
     take z;
       x c= z & y c= z
      proof
       thus x c= z
        proof
         let X be set;
         assume X in x; then X=0 by A14,CARD_5:1,TARSKI:def 1;
         hence X in z by Th1,ENUMSET1:14;
        end;
        thus thesis by A14,XBOOLE_1:36;
      end;
     hence x <= z & y <= z by A1,YELLOW_1:3;
     let z' be Element of N;
       z' is Element of Z by YELLOW_1:1;
     then A15: z'=0 or z'=1 or z'=2\1 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
     assume x <= z' & y <= z';
     then A16:  1 c= z' & 3\2 c= z' by A1,A14,YELLOW_1:3;
A17:  now
      assume A18: z'= 0;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A16,A18;
     end;
A19:  now
      assume A20: z'= 1;
        2 in 3\2 by Th4,TARSKI:def 1;
      hence contradiction by A16,A20,CARD_5:1,TARSKI:def 1;
     end;
A21: now
      assume A22: z'= 2\1;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A16,A22,Th2,TARSKI:def 1;
     end;
       now
      assume A23: z'= 3\2;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A16,A23,Th4,TARSKI:def 1;
     end;
     hence z <= z' by A1,A15,A17,A19,A21,YELLOW_1:3;
     suppose
A24:   x=1 & y=3;
       1 c= 3
      proof
       let X be set;assume X in 1; then X=0 by CARD_5:1,TARSKI:def 1;
       hence thesis by Th1,ENUMSET1:14;
      end;
     then 1 \/ 3 = 3 by XBOOLE_1:12;
     then x \/ y in Z by A24,ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=2\1 & y=0;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A25:   x=2\1 & y=1;
       3 in Z by ENUMSET1:24;
     then 3 in the carrier of N by YELLOW_1:1;
     then reconsider z = 3 as Element of N;
     take z;
       x c= z & y c= z
      proof
       thus x c= z
        proof
         let X be set;
         assume X in x; then X=1 by A25,Th2,TARSKI:def 1;
         hence X in z by Th1,ENUMSET1:14;
        end;
        let X be set;
        assume X in y; then X=0 by A25,CARD_5:1,TARSKI:def 1;
        hence X in z by Th1,ENUMSET1:14;
      end;
     hence x <= z & y <= z by A1,YELLOW_1:3;
     let z' be Element of N;
       z' is Element of Z by YELLOW_1:1;
     then A26: z'=0 or z'=1 or z'=2\1 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
     assume x <= z' & y <= z';
     then A27:  1 c= z' & 2\1 c= z' by A1,A25,YELLOW_1:3;
A28:  now
      assume A29: z'= 0;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A27,A29;
     end;
A30:  now
      assume A31: z'= 1;
        1 in 2\1 by Th2,TARSKI:def 1;
      then 1 in z' by A27;
      hence contradiction by A31;
     end;
A32: now
      assume A33: z'= 2\1;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A27,A33,Th2,TARSKI:def 1;
     end;
       now
      assume A34: z'= 3\2;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A27,A34,Th4,TARSKI:def 1;
     end;
     hence z <= z' by A1,A26,A28,A30,A32,YELLOW_1:3;
     suppose
    x=2\1 & y=2\1;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A35:   x=2\1 & y=3\2;
       3 in Z by ENUMSET1:24;
     then 3 in the carrier of N by YELLOW_1:1;
     then reconsider z = 3 as Element of N;
     take z;
       x c= z & y c= z
      proof
       thus x c= z
        proof
         let X be set;
         assume X in x; then X=1 by A35,Th2,TARSKI:def 1;
         hence X in z by Th1,ENUMSET1:14;
        end;
        let X be set;
        assume X in y; then X=2 by A35,Th4,TARSKI:def 1;
        hence X in z by Th1,ENUMSET1:14;
      end;
     hence x <= z & y <= z by A1,YELLOW_1:3;
     let z' be Element of N;
       z' is Element of Z by YELLOW_1:1;
     then A36: z'=0 or z'=1 or z'=2\1 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
     assume x <= z' & y <= z';
     then A37:  2\1 c= z' & 3\2 c= z' by A1,A35,YELLOW_1:3;
A38:  now
      assume A39: z'= 0;
        1 in 2\1 by Th2,TARSKI:def 1;
      hence contradiction by A37,A39;
     end;
A40:  now
      assume A41: z'= 1;
        1 in 2\1 by Th2,TARSKI:def 1;
      then 1 in z' by A37;
      hence contradiction by A41;
     end;
A42: now
      assume A43: z'= 2\1;
        2 in 3\2 by Th4,TARSKI:def 1;
      hence contradiction by A37,A43,Th2,TARSKI:def 1;
     end;
       now
      assume A44: z'= 3\2;
        1 in 2\1 by Th2,TARSKI:def 1;
      hence contradiction by A37,A44,Th4,TARSKI:def 1;
     end;
     hence z <= z' by A1,A36,A38,A40,A42,YELLOW_1:3;
     suppose
A45:   x=2\1 & y=3;
       2\1 c= 3
      proof
       let X be set;assume X in 2\1; then X=1 by Th2,TARSKI:def 1;
       hence thesis by Th1,ENUMSET1:14;
      end;
     then (2\1) \/ 3 = 3 by XBOOLE_1:12;
     then x \/ y in Z by A45,ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=3\2 & y=0;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A46:   x=3\2 & y=1;
       3 in Z by ENUMSET1:24;
     then 3 in the carrier of N by YELLOW_1:1;
     then reconsider z = 3 as Element of N;
     take z;
       x c= z & y c= z
      proof
       thus x c= z by A46,XBOOLE_1:36;
       thus y c= z
        proof
         let X be set;
         assume X in y; then X=0 by A46,CARD_5:1,TARSKI:def 1;
         hence X in z by Th1,ENUMSET1:14;
        end;
      end;
     hence x <= z & y <= z by A1,YELLOW_1:3;
     let z' be Element of N;
       z' is Element of Z by YELLOW_1:1;
     then A47: z'=0 or z'=1 or z'=2\1 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
     assume x <= z' & y <= z';
     then A48:  1 c= z' & 3\2 c= z' by A1,A46,YELLOW_1:3;
A49:  now
      assume A50: z'= 0;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A48,A50;
     end;
A51:  now
      assume A52: z'= 1;
        2 in 3\2 by Th4,TARSKI:def 1;
      hence contradiction by A48,A52,CARD_5:1,TARSKI:def 1;
     end;
A53: now
      assume A54: z'= 2\1;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A48,A54,Th2,TARSKI:def 1;
     end;
       now
      assume A55: z'= 3\2;
        0 in 1 by CARD_5:1,TARSKI:def 1;
      hence contradiction by A48,A55,Th4,TARSKI:def 1;
     end;
     hence z <= z' by A1,A47,A49,A51,A53,YELLOW_1:3;
     suppose
A56:   x=3\2 & y=2\1;
       3 in Z by ENUMSET1:24;
     then 3 in the carrier of N by YELLOW_1:1;
     then reconsider z = 3 as Element of N;
     take z;
       x c= z & y c= z
      proof
       thus x c= z
        proof
         let X be set;
         assume X in x; then X=2 by A56,Th4,TARSKI:def 1;
         hence X in z by Th1,ENUMSET1:14;
        end;
        let X be set;
        assume X in y; then X=1 by A56,Th2,TARSKI:def 1;
        hence X in z by Th1,ENUMSET1:14;
      end;
     hence x <= z & y <= z by A1,YELLOW_1:3;
     let z' be Element of N;
       z' is Element of Z by YELLOW_1:1;
     then A57: z'=0 or z'=1 or z'=2\1 or z'=3\2 or z'=3 by A1,ENUMSET1:23;
     assume x <= z' & y <= z';
     then A58:  2\1 c= z' & 3\2 c= z' by A1,A56,YELLOW_1:3;
A59:  now
      assume A60: z'= 0;
        1 in 2\1 by Th2,TARSKI:def 1;
      hence contradiction by A58,A60;
     end;
A61:  now
      assume A62: z'= 1;
        1 in 2\1 by Th2,TARSKI:def 1;
      then 1 in z' by A58;
      hence contradiction by A62;
     end;
A63: now
      assume A64: z'= 2\1;
        2 in 3\2 by Th4,TARSKI:def 1;
      hence contradiction by A58,A64,Th2,TARSKI:def 1;
     end;
       now
      assume A65: z'= 3\2;
        1 in 2\1 by Th2,TARSKI:def 1;
      hence contradiction by A58,A65,Th4,TARSKI:def 1;
     end;
     hence z <= z' by A1,A57,A59,A61,A63,YELLOW_1:3;
     suppose
    x=3\2 & y=3\2;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A66:   x=3\2 & y=3;
       3\2 c= 3
      proof
       let X be set;assume X in 3\2; then X=2 by Th4,TARSKI:def 1;
       hence thesis by Th1,ENUMSET1:14;
      end;
     then 3\2 \/ 3 = 3 by XBOOLE_1:12;
     then x \/ y in Z by A66,ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose x=3 & y=0;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A67:   x=3 & y=1;
       1 c= 3
      proof
       let X be set;assume X in 1; then X=0 by CARD_5:1,TARSKI:def 1;
       hence thesis by Th1,ENUMSET1:14;
      end;
     then 1 \/ 3 = 3 by XBOOLE_1:12;
     then x \/ y in Z by A67,ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A68:   x=3 & y=2\1;
       2\1 c= 3
      proof
       let X be set;assume X in 2\1; then X=1 by Th2,TARSKI:def 1;
       hence thesis by Th1,ENUMSET1:14;
      end;
     then (2\1) \/ 3 = 3 by XBOOLE_1:12;
     then x \/ y in Z by A68,ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
A69:   x=3 & y=3\2;
       3\2 c= 3
      proof
       let X be set;assume X in 3\2; then X=2 by Th4,TARSKI:def 1;
       hence thesis by Th1,ENUMSET1:14;
      end;
     then 3\2 \/ 3 = 3 by XBOOLE_1:12;
     then x \/ y in Z by A69,ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
     suppose
    x=3 & y=3;
     then x \/ y in Z by ENUMSET1:24;
     then x \/ y in the carrier of N by YELLOW_1:1;
     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 A1,YELLOW_1:3;
     let w be Element of N;
     assume x <= w & y <= w;
     then x c= w & y c= w by A1,YELLOW_1:3;
     then x \/ y c= w by XBOOLE_1:8;
     hence thesis by A1,YELLOW_1:3;
    end;
 end;
      N is with_infima
     proof
        now
       let x,y be set;
       assume x in Z & y in Z;
       then A70: (x=0 or x=1 or x=2\1 or x=3\2 or x=3) &
       (y=0 or y=1 or y=2\1 or y=3\2 or y=3) by ENUMSET1:23;
             1 misses (2\1) by XBOOLE_1:79;
then A71:       1 /\ (2\1) = 0 by XBOOLE_0:def 7;
A72:       1 /\ (3\2) = 0
        proof
           now let x be set;
          assume x in 1 /\ (3\2);
          then x in 1 & x in (3\2) by XBOOLE_0:def 3;
          then x=0 & x=2 & 0<>2 by Th4,CARD_5:1,TARSKI:def 1;
          hence contradiction;
         end;
         hence thesis by XBOOLE_0:def 1;
        end;
         1 c= 3 by CARD_1:56;
then A73:       1 /\ 3 = 1 by XBOOLE_1:28;
A74:       (2\1) /\ (3\2) = 0
        proof
           now let x be set;
          assume x in (2\1) /\ (3\2);
          then x in (2\1) & x in (3\2) by XBOOLE_0:def 3;
          then x=1 & x=2 & 1<>2 by Th2,Th4,TARSKI:def 1;
          hence contradiction;
         end;
         hence thesis by XBOOLE_0:def 1;
        end;
         (2\1) c= 3
        proof
         let x be set;
         assume x in 2\1;
         then x = 1 by Th2,TARSKI:def 1;
         hence thesis by Th1,ENUMSET1:14;
        end;
       then A75:       (2\1) /\ 3 = 2\1 by XBOOLE_1:28;
         (3\2) c= 3 by XBOOLE_1:36;
        then (3\2) /\ 3 = 3\2 by XBOOLE_1:28;
       hence x /\ y in Z by A70,A71,A72,A73,A74,A75,ENUMSET1:24;
      end;
      hence thesis by A1,YELLOW_1:12;
     end;
 hence thesis by A2,Def2;
end;
end;

theorem Th9:
for L being LATTICE holds
(ex K being full Sublattice of L st N_5,K are_isomorphic) iff
(ex a,b,c,d,e being Element of L st
(a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
a"/\"b = a & a"/\"c = a & c"/\"e = c & d"/\"e = d &
  b"/\"c = a & b"/\"d = b & c"/\"d = a & b"\/"c = e & c"\/"d = e))
 proof
  let L be LATTICE;
  set cn = the carrier of N_5;
A1: cn = {0, 3 \ 1, 2, 3 \ 2, 3} by Def1,YELLOW_1:1;
  then A2: 0 in cn & 3\1 in cn & 2 in cn & 3\2 in cn & 3 in cn by ENUMSET1:24;

  thus (ex K being full Sublattice of L st
  N_5,K are_isomorphic) implies
  (ex a,b,c,d,e being Element of L st
  (a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
  a"/\"b = a & a"/\"c = a & c"/\"e = c & d"/\"e = d &
   b"/\"c = a & b"/\"d = b & c"/\"d = a & b"\/"c = e & c"\/"d = e))
   proof
    given K being full Sublattice of L
    such that
A3:  N_5,K are_isomorphic;
    consider f being map of N_5,K such that
A4:  f is isomorphic by A3,WAYBEL_1:def 8;
A5: K is non empty by A4,WAYBEL_0:def 38;
    reconsider K as non empty SubRelStr of L by A4,WAYBEL_0:def 38;
A6: f is one-to-one monotone by A4,A5,WAYBEL_0:def 38;
    reconsider z = 0 as Element of N_5 by A2;
    reconsider tj = 3\1 as Element of N_5 by A2;
    reconsider dw = 2 as Element of N_5 by A2;
    reconsider td = 3\2 as Element of N_5 by A2;
    reconsider t = 3 as Element of N_5 by A2;
    reconsider cl = the carrier of L as non empty set;
    reconsider ck = the carrier of K as non empty set;
A7: ck = rng f by A4,WAYBEL_0:66;
    reconsider g=f as Function of cn,ck;
    reconsider a=g.z,b=g.td,c =g.dw,d=g.tj,e=g.t as Element of K
                                      ;
    reconsider ck as non empty Subset of cl by YELLOW_0:def 13;
      a in ck & b in ck & c in ck & d in ck & e in ck;
    then reconsider A=a,B=b,C=c,D=d,E=e as Element of L;
    take A,B,C,D,E;
    thus A<>B by A6,Th4,WAYBEL_1:def 1;
    thus A<>C by A6,WAYBEL_1:def 1;
    thus A<>D by A6,Th3,WAYBEL_1:def 1;
    thus A<>E by A6,WAYBEL_1:def 1;
      now
     assume f.td = f.dw;
     then A8:   td = dw by A5,A6,WAYBEL_1:def 1;
       2 in td by Th4,TARSKI:def 1;
     hence contradiction by A8;
    end;
    hence B<>C;
      now
     assume

A9:      f.td = f.tj;
       not 1 in td & 1 in tj by Th3,Th4,TARSKI:def 1,def 2;
     hence contradiction by A5,A6,A9,WAYBEL_1:def 1;
    end;
    hence B<>D;
      now
     assume
A10:      f.td = f.t;
       not 1 in td & 1 in t by Th1,Th4,ENUMSET1:14,TARSKI:def 1;
     hence contradiction by A5,A6,A10,WAYBEL_1:def 1;
    end;
    hence B<>E;
      now
     assume f.dw = f.tj;
     then A11:   dw = tj by A5,A6,WAYBEL_1:def 1;
       2 in tj by Th3,TARSKI:def 2;
     hence contradiction by A11;
    end;
    hence C<>D;
    thus C<>E by A6,WAYBEL_1:def 1;
      now
     assume
A12:     f.tj = f.t;
       not 0 in tj & 0 in t by Th1,Th3,ENUMSET1:14,TARSKI:def 2;
     hence contradiction by A5,A6,A12,WAYBEL_1:def 1;
    end;
    hence D<>E;
A13: {0, 3 \ 1, 2, 3 \ 2, 3} is non empty by ENUMSET1:24;
      z c= td by XBOOLE_1:2;
    then z <= td by A13,Def1,YELLOW_1:3;
    then a <= b by A4,WAYBEL_0:66;
    then A <= B by YELLOW_0:60;
    hence A "/\" B = A by YELLOW_0:25;
      z c= dw by XBOOLE_1:2;
    then z <= dw by A13,Def1,YELLOW_1:3;
    then a <= c by A4,WAYBEL_0:66;
    then A <= C by YELLOW_0:60;
    hence A "/\" C = A by YELLOW_0:25;

      dw c= t by CARD_1:56;
    then dw <= t by A13,Def1,YELLOW_1:3;
    then c <= e by A4,WAYBEL_0:66;
    then C <= E by YELLOW_0:60;
    hence C"/\"E = C by YELLOW_0:25;

      tj c= t by XBOOLE_1:36;
    then tj <= t by A13,Def1,YELLOW_1:3;
    then d <= e by A4,WAYBEL_0:66;
    then D <= E by YELLOW_0:60;
    hence D"/\"E = D by YELLOW_0:25;

    thus B"/\"C = A
     proof
        B in the carrier of K & C in the carrier of K & ex_inf_of {B,C},L
                                  by YELLOW_0:21;
      then inf{B,C} in the carrier of K by YELLOW_0:def 16;
      then B"/\"C in rng f by A7,YELLOW_0:40;
      then consider x being set such that
A14:    x in dom f & B"/\"C = f.x by FUNCT_1:def 5;
        f is Function of the carrier of N_5,the carrier of K;
      then dom f = the carrier of N_5 by FUNCT_2:def 1;
      then reconsider x as Element of N_5 by A14;
A15:      x = z or x = td or x = dw or x = tj or x = t by A1,ENUMSET1:23;
A16:    now
       assume B"/\"C = B;
       then B <= C by YELLOW_0:25;
       then b <= c by YELLOW_0:61;
       then td <= dw by A4,WAYBEL_0:66;
       then A17:    td c= dw by A13,Def1,YELLOW_1:3;
         2 in td by Th4,TARSKI:def 1;
       then 2 in 2 by A17;
       hence contradiction;
      end;
A18:    now
       assume B"/\"C = C;
       then C <= B by YELLOW_0:25;
       then c <= b by YELLOW_0:61;
       then dw <= td by A4,WAYBEL_0:66;
       then A19:    dw c= td by A13,Def1,YELLOW_1:3;
         0 in dw & 0 <> 2 by CARD_5:1,TARSKI:def 2;
       hence contradiction by A19,Th4,TARSKI:def 1;
      end;
A20:    now
       assume B"/\"C = D;
       then D <= C by YELLOW_0:23;
       then d <= c by YELLOW_0:61;
       then tj <= dw by A4,WAYBEL_0:66;
       then A21:    tj c= dw by A13,Def1,YELLOW_1:3;
         2 in tj by Th3,TARSKI:def 2;
       then 2 in 2 by A21;
       hence contradiction;
      end;
        now
       assume B"/\"C = E;
       then E <= C by YELLOW_0:23;
       then e <= c by YELLOW_0:61;
       then t <= dw by A4,WAYBEL_0:66;
       then A22:    t c= dw by A13,Def1,YELLOW_1:3;
         2 in t by Th1,ENUMSET1:14;
       then 2 in 2 by A22;
       hence contradiction;
      end;
      hence thesis by A14,A15,A16,A18,A20;
     end;

      td <= tj by A13,Def1,Lm1,YELLOW_1:3;
    then b <= d by A4,WAYBEL_0:66;
    then B <= D by YELLOW_0:60;
    hence B"/\"D = B by YELLOW_0:25;

    thus C"/\"D = A
     proof
        C in the carrier of K & D in the carrier of K & ex_inf_of {C,D},L
                                  by YELLOW_0:21;
      then inf{C,D} in the carrier of K by YELLOW_0:def 16;
      then C"/\"D in rng f by A7,YELLOW_0:40;
      then consider x being set such that
A23:    x in dom f & C"/\"D = f.x by FUNCT_1:def 5;
        f is Function of the carrier of N_5,the carrier of K;
      then dom f = the carrier of N_5 by FUNCT_2:def 1;
      then reconsider x as Element of N_5 by A23;
A24:      x = z or x = td or x = dw or x = tj or x = t by A1,ENUMSET1:23;
A25:    now
       assume C"/\"D = B;
       then B <= C by YELLOW_0:23;
       then b <= c by YELLOW_0:61;
       then td <= dw by A4,WAYBEL_0:66;
       then A26:    td c= dw by A13,Def1,YELLOW_1:3;
         2 in td by Th4,TARSKI:def 1;
       then 2 in 2 by A26;
       hence contradiction;
      end;
A27:    now
       assume C"/\"D = C;
       then C <= D by YELLOW_0:25;
       then c <= d by YELLOW_0:61;
       then dw <= tj by A4,WAYBEL_0:66;
       then A28:    dw c= tj by A13,Def1,YELLOW_1:3;
         0 in dw & 0 <> 2 & 0 <> 1 by CARD_5:1,TARSKI:def 2;
       hence contradiction by A28,Th3,TARSKI:def 2;
      end;
A29:    now
       assume C"/\"D = D;
       then D <= C by YELLOW_0:23;
       then d <= c by YELLOW_0:61;
       then tj <= dw by A4,WAYBEL_0:66;
       then A30:    tj c= dw by A13,Def1,YELLOW_1:3;
         2 in tj by Th3,TARSKI:def 2;
       then 2 in 2 by A30;
       hence contradiction;
      end;
        now
       assume C"/\"D = E;
       then E <= C by YELLOW_0:23;
       then e <= c by YELLOW_0:61;
       then t <= dw by A4,WAYBEL_0:66;
       then A31:    t c= dw by A13,Def1,YELLOW_1:3;
         2 in t by Th1,ENUMSET1:14;
       then 2 in 2 by A31;
       hence contradiction;
      end;
      hence thesis by A23,A24,A25,A27,A29;
     end;

    thus B"\/"C = E
     proof
        B in the carrier of K & B in the carrier of K & ex_sup_of {B,C},L
                                  by YELLOW_0:20;
      then sup{B,C} in the carrier of K by YELLOW_0:def 17;
      then B"\/"C in rng f by A7,YELLOW_0:41;
      then consider x being set such that
A32:    x in dom f & B"\/"C = f.x by FUNCT_1:def 5;
        f is Function of the carrier of N_5,the carrier of K;
      then dom f = the carrier of N_5 by FUNCT_2:def 1;
      then reconsider x as Element of N_5 by A32;
A33:      x = z or x = td or x = dw or x = tj or x = t by A1,ENUMSET1:23;
A34:    now
       assume B"\/"C = B;
       then B >= C by YELLOW_0:24;
       then b >= c by YELLOW_0:61;
       then td >= dw by A4,WAYBEL_0:66;
       then A35:    dw c= td by A13,Def1,YELLOW_1:3;
         0 in dw & 0 <> 2 by CARD_5:1,TARSKI:def 2;
       hence contradiction by A35,Th4,TARSKI:def 1;
      end;
A36:    now
       assume B"\/"C = C;
       then C >= B by YELLOW_0:24;
       then c >= b by YELLOW_0:61;
       then dw >= td by A4,WAYBEL_0:66;
       then A37:    td c= dw by A13,Def1,YELLOW_1:3;
         2 in td by Th4,TARSKI:def 1;
       then 2 in 2 by A37;
       hence contradiction;
      end;
A38:    now
       assume B"\/"C = D;
       then D >= C by YELLOW_0:22;
       then d >= c by YELLOW_0:61;
       then tj >= dw by A4,WAYBEL_0:66;
       then A39:    dw c= tj by A13,Def1,YELLOW_1:3;
         0 in dw & 0 <> 1 & 0 <>2 by CARD_5:1,TARSKI:def 2;
       hence contradiction by A39,Th3,TARSKI:def 2;
      end;
        now
       assume B"\/"C = A;
       then A >= C by YELLOW_0:22;
       then a >= c by YELLOW_0:61;
       then z >= dw by A4,WAYBEL_0:66;
       then dw c= z by A13,Def1,YELLOW_1:3;
       hence contradiction by XBOOLE_1:3;
      end;
      hence thesis by A32,A33,A34,A36,A38;
     end;

    thus C"\/"D = E
     proof
        C in the carrier of K & D in the carrier of K & ex_sup_of {C,D},L
                                  by YELLOW_0:20;
      then sup{C,D} in the carrier of K by YELLOW_0:def 17;
      then C"\/"D in rng f by A7,YELLOW_0:41;
      then consider x being set such that
A40:    x in dom f & C"\/"D = f.x by FUNCT_1:def 5;
        f is Function of the carrier of N_5,the carrier of K;
      then dom f = the carrier of N_5 by FUNCT_2:def 1;
      then reconsider x as Element of N_5 by A40;
A41:      x = z or x = td or x = dw or x = tj or x = t by A1,ENUMSET1:23;
A42:    now
       assume C"\/"D = B;
       then B >= C by YELLOW_0:22;
       then b >= c by YELLOW_0:61;
       then td >= dw by A4,WAYBEL_0:66;
       then A43:    dw c= td by A13,Def1,YELLOW_1:3;
         0 in dw & 0 <> 2 by CARD_5:1,TARSKI:def 2;
       hence contradiction by A43,Th4,TARSKI:def 1;
      end;
A44:    now
       assume C"\/"D = C;
       then C >= D by YELLOW_0:24;
       then c >= d by YELLOW_0:61;
       then dw >= tj by A4,WAYBEL_0:66;
       then A45:    tj c= dw by A13,Def1,YELLOW_1:3;
         2 in tj & 2 <> 0 & 2 <> 1 by Th3,TARSKI:def 2;
       hence contradiction by A45,CARD_5:1,TARSKI:def 2;
      end;
A46:    now
       assume C"\/"D = D;
       then D >= C by YELLOW_0:22;
       then d >= c by YELLOW_0:61;
       then tj >= dw by A4,WAYBEL_0:66;
       then A47:    dw c= tj by A13,Def1,YELLOW_1:3;
         0 in dw & 0 <>1 & 0 <> 2 by CARD_5:1,TARSKI:def 2;
       hence contradiction by A47,Th3,TARSKI:def 2;
      end;
        now
       assume C"\/"D = A;
       then A >= C by YELLOW_0:22;
       then a >= c by YELLOW_0:61;
       then z >= dw by A4,WAYBEL_0:66;
       then dw c= z by A13,Def1,YELLOW_1:3;
       hence contradiction by XBOOLE_1:3;
      end;
      hence thesis by A40,A41,A42,A44,A46;
     end;
   end;
  thus (ex a,b,c,d,e being Element of L st
  (a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
  a"/\"b = a & a"/\"c = a & c"/\"e = c & d"/\"e = d &
   b"/\"c = a & b"/\"d = b & c"/\"d = a & b"\/"c = e & c"\/"d = e)) implies
  (ex K being full Sublattice of L
  st N_5,K are_isomorphic)
   proof
    given a,b,c,d,e being Element of L such that
A48:  (a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
      a"/\"b = a & a"/\"c = a & c"/\"e = c & d"/\"e = d &
     b"/\"c = a & b"/\"d = b & c"/\"d = a & b"\/"c = e & c"\/"d = e);

    set ck = {a,b,c,d,e};
      now
     let x be set;
     assume x in ck;
     then x=a or x=b or x=c or x=d or x=e by ENUMSET1:23;
     hence x in the carrier of L;
    end;
    then reconsider ck as Subset of L by TARSKI:def 3;
    set K = subrelstr ck;
A49: the carrier of K = ck by YELLOW_0:def 15;
A50:    a in ck by ENUMSET1:24;
A51:  K is meet-inheriting
     proof
      let x,y be Element of L;
      assume
A52:      x in the carrier of K & y in the carrier of K & ex_inf_of {x,y},L;
      per cases by A49,A52,ENUMSET1:23;
      suppose x=a & y=a;
      then inf{x,y} = a"/\"a by YELLOW_0:40;
      then inf{x,y} = a by YELLOW_5:2;
      hence thesis by A49,ENUMSET1:24;
      suppose x=a & y=b;
      then inf{x,y} = a"/\"b by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=a & y=c;
      then inf{x,y} = a"/\"c by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose
A53:    x=a & y=d;
        a <= b & b <= d by A48,YELLOW_0:25;
      then a <= d by ORDERS_1:26;
      then a"/\"d = a by YELLOW_0:25;
      then inf {x,y} = a by A53,YELLOW_0:40;
      hence thesis by A49,ENUMSET1:24;
      suppose
A54:    x=a & y=e;
        a <= c & c <= e by A48,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then inf {x,y} = a by A54,YELLOW_0:40;
      hence thesis by A49,ENUMSET1:24;
      suppose x=b & y=a;
      then inf{x,y} = a"/\"b by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=b & y=b;
      then inf{x,y} = b"/\"b by YELLOW_0:40;
      then inf{x,y} = b by YELLOW_5:2;
      hence thesis by A49,ENUMSET1:24;
      suppose x=b & y=c;
      then inf{x,y} = b"/\"c by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=b & y=d;
      then inf{x,y} = b"/\"d by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose
A55:    x=b & y=e;
        b <= d & d <= e by A48,YELLOW_0:25;
      then b <= e by ORDERS_1:26;
      then b"/\"e = b by YELLOW_0:25;
      then inf {x,y} = b by A55,YELLOW_0:40;
      hence thesis by A49,ENUMSET1:24;
      suppose x=c & y=a;
      then inf{x,y} = a"/\"c by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=c & y=b;
      then inf{x,y} = b"/\"c by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=c & y=c;
      then inf{x,y} = c"/\"c by YELLOW_0:40;
      then inf{x,y} = c by YELLOW_5:2;
      hence thesis by A49,ENUMSET1:24;
      suppose x=c & y=d;
      then inf{x,y} = c"/\"d by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=c & y=e;
      then inf{x,y} = c"/\"e by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose
A56:    x=d & y=a;
        a <= b & b <= d by A48,YELLOW_0:25;
      then a <= d by ORDERS_1:26;
      then a"/\"d = a by YELLOW_0:25;
      then inf {x,y} = a by A56,YELLOW_0:40;
      hence thesis by A49,ENUMSET1:24;
      suppose x=d & y=b;
      then inf{x,y} = b"/\"d by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=d & y=c;
      then inf{x,y} = c"/\"d by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=d & y=d;
      then inf{x,y} = d"/\"d by YELLOW_0:40;
      then inf{x,y} = d by YELLOW_5:2;
      hence thesis by A49,ENUMSET1:24;
      suppose x=d & y=e;
      then inf{x,y} = d"/\"e by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose
A57:    x=e & y=a;
        a <= c & c <= e by A48,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then inf {x,y} = a by A57,YELLOW_0:40;
      hence thesis by A49,ENUMSET1:24;
      suppose
A58:    x=e & y=b;
        b <= d & d <= e by A48,YELLOW_0:25;
      then b <= e by ORDERS_1:26;
      then b"/\"e = b by YELLOW_0:25;
      then inf {x,y} = b by A58,YELLOW_0:40;
      hence thesis by A49,ENUMSET1:24;
      suppose x=e & y=c;
      then inf{x,y} = c"/\"e by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=e & y=d;
      then inf{x,y} = d"/\"e by YELLOW_0:40;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=e & y=e;
      then inf{x,y} = e"/\"e by YELLOW_0:40;
      then inf{x,y} = e by YELLOW_5:2;
      hence thesis by A49,ENUMSET1:24;
     end;
      K is join-inheriting
     proof
      let x,y be Element of L;
      assume
A59:      x in the carrier of K & y in the carrier of K & ex_sup_of {x,y},L;
      per cases by A49,A59,ENUMSET1:23;
      suppose x=a & y=a;
      then sup{x,y} = a"\/"a by YELLOW_0:41;
      then sup{x,y} = a by YELLOW_5:1;
      hence thesis by A49,ENUMSET1:24;
      suppose x=a & y=b;
      then x"\/"y = b by A48,Th5;
      then sup{x,y} = b by YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose x=a & y=c;
      then x"\/"y = c by A48,Th5;
      then sup{x,y} = c by YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A60:    x=a & y=d;
        a <= b & b <= d by A48,YELLOW_0:25;
      then a <= d by ORDERS_1:26;
      then a"/\"d = a by YELLOW_0:25;
      then a"\/"d = d by Th5;
      then sup {x,y} = d by A60,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A61:    x=a & y=e;
        a <= c & c <= e by A48,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then a"\/"e = e by Th5;
      then sup {x,y} = e by A61,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A62:    x=b & y=a;
        a"\/"b = b by A48,Th5;
      then sup{x,y} = b by A62,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose x=b & y=b;
      then sup{x,y} = b"\/"b by YELLOW_0:41;
      then sup{x,y} = b by YELLOW_5:1;
      hence thesis by A49,ENUMSET1:24;
      suppose x=b & y=c;
      then sup{x,y} = b"\/"c by YELLOW_0:41;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose
A63:    x=b & y=d;
        b"\/"d = d by A48,Th5;
      then sup{x,y} = d by A63,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A64:    x=b & y=e;
        b <= d & d <= e by A48,YELLOW_0:25;
      then b <= e by ORDERS_1:26;
      then b"/\"e = b by YELLOW_0:25;
      then b"\/"e = e by Th5;
      then sup {x,y} = e by A64,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A65:    x=c & y=a;
        c"\/"a = c by A48,Th5;
      then sup{x,y} = c by A65,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose x=c & y=b;
      then sup{x,y} = b"\/"c by YELLOW_0:41;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=c & y=c;
      then sup{x,y} = c"\/"c by YELLOW_0:41;
      then sup{x,y} = c by YELLOW_5:1;
      hence thesis by A49,ENUMSET1:24;
      suppose x=c & y=d;
      then sup{x,y} = c"\/"d by YELLOW_0:41;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose
A66:    x=c & y=e;
        c"\/"e = e by A48,Th5;
      then sup{x,y} = e by A66,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A67:    x=d & y=a;
        a <= b & b <= d by A48,YELLOW_0:25;
      then a <= d by ORDERS_1:26;
      then a"/\"d = a by YELLOW_0:25;
      then a"\/"d = d by Th5;
      then sup {x,y} = d by A67,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A68:    x=d & y=b;
        b"\/"d = d by A48,Th5;
      then sup{x,y} = d by A68,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose x=d & y=c;
      then sup{x,y} = c"\/"d by YELLOW_0:41;
      hence thesis by A48,A49,ENUMSET1:24;
      suppose x=d & y=d;
      then sup{x,y} = d"\/"d by YELLOW_0:41;
      then sup{x,y} = d by YELLOW_5:1;
      hence thesis by A49,ENUMSET1:24;
      suppose
A69:    x=d & y=e;
        d"\/"e = e by A48,Th5;
      then sup{x,y} = e by A69,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A70:    x=e & y=a;
        a <= c & c <= e by A48,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then a"\/"e = e by Th5;
      then sup {x,y} = e by A70,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A71:    x=e & y=b;
        b <= d & d <= e by A48,YELLOW_0:25;
      then b <= e by ORDERS_1:26;
      then b"/\"e = b by YELLOW_0:25;
      then b"\/"e = e by Th5;
      then sup {x,y} = e by A71,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A72:    x=e & y=c;
        c"\/"e = e by A48,Th5;
      then sup{x,y} = e by A72,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose
A73:    x=e & y=d;
        d"\/"e = e by A48,Th5;
      then sup{x,y} = e by A73,YELLOW_0:41;
      hence thesis by A49,ENUMSET1:24;
      suppose x=e & y=e;
      then sup{x,y} = e"\/"e by YELLOW_0:41;
      then sup{x,y} = e by YELLOW_5:1;
      hence thesis by A49,ENUMSET1:24;
     end;
    then reconsider K as non empty full Sublattice of L
           by A49,A50,A51,STRUCT_0:def 1;
    take K;
    thus N_5,K are_isomorphic
     proof
      reconsider z = 0 as Element of N_5 by A2;
      reconsider tj = 3\1 as Element of N_5 by A2;
      reconsider dw = 2 as Element of N_5 by A2;
      reconsider td = 3\2 as Element of N_5 by A2;
      reconsider t = 3 as Element of N_5 by A2;

A74: now
       assume
    A75: tj=dw;
         2 in tj by Th3,TARSKI:def 2;
       hence contradiction by A75;
      end;
A76: now
       assume
    A77: tj=td;
         not 1 in td & 1 in tj by Th3,Th4,TARSKI:def 1,def 2;
       hence contradiction by A77;
      end;
A78:  now
       assume
    A79: tj=t;
         not 0 in tj & 0 in t by Th1,Th3,ENUMSET1:14,TARSKI:def 2;
       hence contradiction by A79;
      end;
A80: now
       assume
    A81: dw=td; 2 in td by Th4,TARSKI:def 1;
       hence contradiction by A81;
      end;
A82:  now
       assume
    A83: td=t;
         not 1 in td & 1 in t by Th1,Th4,ENUMSET1:14,TARSKI:def 1;
       hence contradiction by A83;
      end;
      defpred P[set,set] means
      for X being Element of N_5 st X=$1 holds
     ((X = z implies $2 = a) &
      (X = td implies $2 = b) &
      (X = dw implies $2 = c) &
      (X = tj implies $2 = d) &
      (X = t implies $2 = e));

A84:   for x being set st x in cn ex y being set st y in ck & P[x,y]
       proof
        let x be set;
        assume
A85:         x in cn;
        per cases by A1,A85,ENUMSET1:23;
        suppose
A86:      x = 0;
        take y=a;
        thus y in ck by ENUMSET1:24;
        let X be Element of N_5;
        thus thesis by A86,Th3,Th4;
        suppose
A87:      x=3\1;
        take y=d;
        thus y in ck by ENUMSET1:24;
        let X be Element of N_5;
        thus thesis by A74,A76,A78,A87,Th3;
        suppose
A88:      x = 2;
        take y=c;
        thus y in ck by ENUMSET1:24;
        let X be Element of N_5;
        thus thesis by A74,A80,A88;
        suppose
A89:      x = 3 \ 2;
        take y=b;
        thus y in ck by ENUMSET1:24;
        let X be Element of N_5;
        thus thesis by A76,A80,A82,A89,Th4;
        suppose
A90:      x = 3;
        take y=e;
        thus y in ck by ENUMSET1:24;
        let X be Element of N_5;
        thus thesis by A78,A82,A90;
       end;
      consider f being Function of cn,ck such that
A91:    for x being set st x in cn holds P[x,f.x] from FuncEx1(A84);
      reconsider f as map of N_5,K by A49;
      take f;
A92:  f is one-to-one
       proof
          now
         let x,y be Element of N_5;
         assume
A93:      f.x = f.y;
         thus x=y
          proof
           per cases by A1,ENUMSET1:23;
           suppose x = z & y = z;hence thesis;
           suppose x = tj & y = tj;hence thesis;
           suppose x = td & y = td;hence thesis;
           suppose x = dw & y = dw;hence thesis;
           suppose x = t & y = t;hence thesis;
           suppose x = z & y = tj;
           then f.x=a & f.y=d by A91;
           hence thesis by A48,A93;
           suppose x = z & y = dw;
           then f.x=a & f.y=c by A91;
           hence thesis by A48,A93;
           suppose x = z & y = td;
           then f.x=a & f.y=b by A91;
           hence thesis by A48,A93;
           suppose x = z & y = t;
           then f.x=a & f.y=e by A91;
           hence thesis by A48,A93;
           suppose x = tj & y = z;
           then f.x=d & f.y=a by A91;
           hence thesis by A48,A93;
           suppose x = tj & y = dw;
           then f.x=d & f.y=c by A91;
           hence thesis by A48,A93;
           suppose x = tj & y = td;
           then f.x=d & f.y=b by A91;
           hence thesis by A48,A93;
           suppose x = tj & y = t;
           then f.x=d & f.y=e by A91;
           hence thesis by A48,A93;
           suppose x = dw & y = z;
           then f.x=c & f.y=a by A91;
           hence thesis by A48,A93;
           suppose x = dw & y = tj;
           then f.x=c & f.y=d by A91;
           hence thesis by A48,A93;
           suppose x = dw & y = td;
           then f.x=c & f.y=b by A91;
           hence thesis by A48,A93;
           suppose x = dw & y = t;
           then f.x=c & f.y=e by A91;
           hence thesis by A48,A93;
           suppose x = td & y = z;
           then f.x=b & f.y=a by A91;
           hence thesis by A48,A93;
           suppose x = td & y = tj;
           then f.x=b & f.y=d by A91;
           hence thesis by A48,A93;
           suppose x = td & y = dw;
           then f.x=b & f.y=c by A91;
           hence thesis by A48,A93;
           suppose x = td & y = t;
           then f.x=b & f.y=e by A91;
           hence thesis by A48,A93;
           suppose x = t & y = z;
           then f.x=e & f.y=a by A91;
           hence thesis by A48,A93;
           suppose x = t & y = tj;
           then f.x=e & f.y=d by A91;
           hence thesis by A48,A93;
           suppose x = t & y = dw;
           then f.x=e & f.y=c by A91;
           hence thesis by A48,A93;
           suppose x = t & y = td;
           then f.x=e & f.y=b by A91;
           hence thesis by A48,A93;
          end;
        end;
        hence thesis by WAYBEL_1:def 1;
       end;
A94: dom f = the carrier of N_5 by FUNCT_2:def 1;
A95: rng f = ck
       proof
        thus rng f c= ck
         proof
          let y be set;
          assume y in rng f;
          then consider x being set such that
A96:        x in dom f & y=f.x by FUNCT_1:def 5;
            x in the carrier of N_5 by A96,FUNCT_2:def 1;
          then reconsider x as Element of N_5;
            (x = z or x = tj or x = dw or x = td or x = t) by A1,ENUMSET1:23;
          then y=a or y=d or y=c or y=b or y=e by A91,A96;
          hence thesis by ENUMSET1:24;
         end;
        thus ck c= rng f
         proof
          let y be set;
          assume
A97:          y in ck;
          per cases by A97,ENUMSET1:23;
          suppose
A98:        y=a;
            z in dom f & a = f.z by A91,A94;
          hence y in rng f by A98,FUNCT_1:def 5;
          suppose
A99:        y=b;
            td in dom f & b=f.td by A91,A94;
          hence y in rng f by A99,FUNCT_1:def 5;
          suppose
A100:        y=c;
            dw in dom f & c = f.dw by A91,A94;
          hence y in rng f by A100,FUNCT_1:def 5;
          suppose
A101:        y=d;
            tj in dom f & d=f.tj by A91,A94;
          hence y in rng f by A101,FUNCT_1:def 5;
          suppose
A102:        y=e;
            t in dom f & e=f.t by A91,A94;
          hence y in rng f by A102,FUNCT_1:def 5;
         end;
       end;
        for x,y being Element of N_5 holds x <= y iff f.x <= f.y
       proof
        let x,y be Element of N_5;
A103:     {0, 3 \ 1, 2, 3 \ 2, 3} is non empty by ENUMSET1:24;
        thus x <= y implies f.x <= f.y
         proof
          assume
A104:       x <= y;
          per cases by A1,ENUMSET1:23;
          suppose x=z & y=z;hence thesis;
          suppose x=z & y=td;
          then A105:       f.x = a & f.y = b by A91;
            a in the carrier of K & b in the carrier of K by A49,ENUMSET1:24;
          then reconsider A=a,B=b as Element of K;
            a <= b & A in the carrier of K & B in the carrier of K
                                          by A48,YELLOW_0:25;
          hence f.x <= f.y by A105,YELLOW_0:61;
          suppose x=z & y=dw;
          then A106:       f.x = a & f.y = c by A91;
            a in the carrier of K & c in the carrier of K by A49,ENUMSET1:24;
          then reconsider A=a,C=c as Element of K;
            a <= c & A in the carrier of K & C in the carrier of K
                                          by A48,YELLOW_0:25;
          hence f.x <= f.y by A106,YELLOW_0:61;
          suppose x=z & y=tj;
          then A107:       f.x = a & f.y = d by A91;
            a in the carrier of K & d in the carrier of K by A49,ENUMSET1:24;
          then reconsider A=a,D=d as Element of K;
            a <= b & b <= d by A48,YELLOW_0:25;
          then a <= d & A in the carrier of K & D in the carrier of K
                                          by ORDERS_1:26;
          hence f.x <= f.y by A107,YELLOW_0:61;
          suppose x=z & y=t;
          then A108:       f.x = a & f.y = e by A91;
            a in the carrier of K & e in the carrier of K by A49,ENUMSET1:24;
          then reconsider A=a,E=e as Element of K;
            a <= c & c <= e by A48,YELLOW_0:25;
          then a <= e & A in the carrier of K & E in the carrier of K
                                          by ORDERS_1:26;
          hence f.x <= f.y by A108,YELLOW_0:61;
          suppose x=td & y=z;
          then td c= z by A103,A104,Def1,YELLOW_1:3;
          hence thesis by Th4,XBOOLE_1:3;
          suppose x=td & y=td;hence thesis;
          suppose
A109:        x=td & y=dw;
            2 in td & not 2 in dw by Th4,TARSKI:def 1;
          then not td c= dw;
          hence thesis by A103,A104,A109,Def1,YELLOW_1:3;
          suppose x=td & y=z;
          then td c= z by A103,A104,Def1,YELLOW_1:3;
          hence thesis by Th4,XBOOLE_1:3;
          suppose x=td & y=tj;
          then A110:       f.x = b & f.y = d by A91;
            b in the carrier of K & d in the carrier of K by A49,ENUMSET1:24;
          then reconsider D=d,B=b as Element of K;
            b <= d & B in the carrier of K & D in the carrier of K
                                          by A48,YELLOW_0:25;
          hence f.x <= f.y by A110,YELLOW_0:61;
          suppose x=td & y=t;
          then A111:       f.x = b & f.y = e by A91;
            b in the carrier of K & e in the carrier of K by A49,ENUMSET1:24;
          then reconsider B=b,E=e as Element of K;
            b <= d & d <= e by A48,YELLOW_0:25;
          then b <= e & B in the carrier of K & E in the carrier of K
                                          by ORDERS_1:26;
          hence f.x <= f.y by A111,YELLOW_0:61;
          suppose x=dw & y=z;
          then dw c= z by A103,A104,Def1,YELLOW_1:3;
          hence thesis by XBOOLE_1:3;
          suppose
A112:        x=dw & y=td;
            0 in dw & not 0 in td by Th4,CARD_5:1,TARSKI:def 1,def 2;
          then not dw c= td;
          hence thesis by A103,A104,A112,Def1,YELLOW_1:3;
          suppose x=dw & y=dw;hence thesis;
          suppose
A113:        x=dw & y=tj;
            0 in dw & not 0 in tj by Th3,CARD_5:1,TARSKI:def 2;
          then not dw c= tj;
          hence thesis by A103,A104,A113,Def1,YELLOW_1:3;
          suppose x=dw & y=t;
          then A114:       f.x = c & f.y = e by A91;
            c in the carrier of K & e in the carrier of K by A49,ENUMSET1:24;
          then reconsider C=c,E=e as Element of K;
            c <= e & C in the carrier of K & E in the carrier of K
                                          by A48,YELLOW_0:25;
          hence f.x <= f.y by A114,YELLOW_0:61;
          suppose x=tj & y=z;
          then tj c= z by A103,A104,Def1,YELLOW_1:3;
          hence thesis by Th3,XBOOLE_1:3;
          suppose
A115:        x=tj & y=td;
            1 in tj & not 1 in td by Th3,Th4,TARSKI:def 1,def 2;
          then not tj c= td;
          hence thesis by A103,A104,A115,Def1,YELLOW_1:3;
          suppose
A116:        x=tj & y=dw;
            2 in tj & not 2 in dw by Th3,TARSKI:def 2;
          then not tj c= dw;
          hence thesis by A103,A104,A116,Def1,YELLOW_1:3;
          suppose x=tj & y=tj;hence thesis;
          suppose x=tj & y=t;
          then A117:       f.x = d & f.y = e by A91;
            d in the carrier of K & e in the carrier of K by A49,ENUMSET1:24;
          then reconsider D=d,E=e as Element of K;
            d <= e & D in the carrier of K & E in the carrier of K
                                          by A48,YELLOW_0:25;
          hence f.x <= f.y by A117,YELLOW_0:61;
          suppose x=t & y=z;
          then t c= z by A103,A104,Def1,YELLOW_1:3;
          hence thesis by XBOOLE_1:3;
          suppose
A118:        x=t & y=td;
            0 in t & not 0 in td by Th1,Th4,ENUMSET1:14,TARSKI:def 1;
          then not t c= td;
          hence thesis by A103,A104,A118,Def1,YELLOW_1:3;
          suppose
A119:        x=t & y=dw;
            2 in t & not 2 in dw by Th1,ENUMSET1:14;
          then not t c= dw;
          hence thesis by A103,A104,A119,Def1,YELLOW_1:3;
          suppose
A120:        x=t & y=tj;
            0 in t & not 0 in tj by Th1,Th3,ENUMSET1:14,TARSKI:def 2;
          then not t c= tj;
          hence thesis by A103,A104,A120,Def1,YELLOW_1:3;
          suppose x=t & y=t;hence thesis;
         end;
        thus f.x <= f.y implies x <= y
         proof
          assume
A121:       f.x <= f.y;
A122:          f.x in ck & f.y in ck by A94,A95,FUNCT_1:def 5;
          per cases by A122,ENUMSET1:23;
          suppose f.x = a & f.y = a;
          hence x <= y by A92,WAYBEL_1:def 1;
          suppose A123: f.x = a & f.y = b;
            f.z = a & f.td = b by A91;
          then z=x & td = y by A92,A123,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A103,Def1,YELLOW_1:3;
          suppose A124: f.x = a & f.y = c;
            f.z = a & f.dw = c by A91;
          then z=x & dw = y by A92,A124,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A103,Def1,YELLOW_1:3;
          suppose A125: f.x = a & f.y = d;
            f.z = a & f.tj = d by A91;
          then z=x & tj = y by A92,A125,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A103,Def1,YELLOW_1:3;
          suppose A126: f.x = a & f.y = e;
            f.z = a & f.t = e by A91;
          then z=x & t = y by A92,A126,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A103,Def1,YELLOW_1:3;
          suppose f.x = b & f.y = a;
          then b <= a by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = b & f.y = b;
          hence x <= y by A92,WAYBEL_1:def 1;
          suppose f.x = b & f.y = c;
          then b <= c by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose A127: f.x = b & f.y = d;
            f.td = b & f.tj = d by A91;
          then x=td & y=tj & 1 c= 2 by A92,A127,CARD_1:56,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:34;
          hence x <= y by A103,Def1,YELLOW_1:3;
          suppose A128: f.x = b & f.y = e;
A129:      td c= t
           proof
            let X be set;
            assume X in td;
            then X = 2 by Th4,TARSKI:def 1;
            hence thesis by Th1,ENUMSET1:14;
           end;
            f.td = b & f.t = e by A91;
          then td=x & t = y by A92,A128,WAYBEL_1:def 1;
          hence x <= y by A103,A129,Def1,YELLOW_1:3;
          suppose f.x = c & f.y = a;
          then c <= a by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = c & f.y = b;
          then c <= b by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = c & f.y = c;
          hence x <= y by A92,WAYBEL_1:def 1;
          suppose f.x = c & f.y = d;
          then c <= d by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose A130: f.x = c & f.y = e;
A131:      dw c= t
           proof
            let X be set;
            assume X in dw;
            then X=0 or X=1 by CARD_5:1,TARSKI:def 2;
            hence thesis by Th1,ENUMSET1:14;
           end;
            f.dw = c & f.t = e by A91;
          then dw=x & t = y by A92,A130,WAYBEL_1:def 1;
          hence x <= y by A103,A131,Def1,YELLOW_1:3;
          suppose f.x = d & f.y = a;
          then d <= a & a <= b by A48,A121,YELLOW_0:25,60;
          then d <= b by ORDERS_1:26;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = d & f.y = b;
          then d <= b by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = d & f.y = c;
          then d <= c by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = d & f.y = d;
          hence x <= y by A92,WAYBEL_1:def 1;
          suppose A132: f.x = d & f.y = e;
A133:      tj c= t
           proof
            let X be set;
            assume X in tj;
            then X=2 or X=1 by Th3,TARSKI:def 2;
            hence thesis by Th1,ENUMSET1:14;
           end;
            f.tj = d & f.t = e by A91;
          then tj=x & t = y by A92,A132,WAYBEL_1:def 1;
          hence x <= y by A103,A133,Def1,YELLOW_1:3;
          suppose f.x = e & f.y = a;
          then A134:        e <= a by A121,YELLOW_0:60;
            a <= b & b <= d & d <= e by A48,YELLOW_0:25;
          then a <= d & d <= e by ORDERS_1:26;
          then a <= e by ORDERS_1:26;
          hence x <= y by A48,A134,ORDERS_1:25;
          suppose f.x = e & f.y = b;
          then A135:        e <= b by A121,YELLOW_0:60;
            b <= d & d <= e by A48,YELLOW_0:25;
          then b <= e by ORDERS_1:26;
          hence x <= y by A48,A135,ORDERS_1:25;
          suppose f.x = e & f.y = c;
          then e <= c by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = e & f.y = d;
          then e <= d by A121,YELLOW_0:60;
          hence x <= y by A48,YELLOW_0:25;
          suppose f.x = e & f.y = e;
          hence x <= y by A92,WAYBEL_1:def 1;
         end;
       end;
      hence f is isomorphic by A49,A92,A95,WAYBEL_0:66;
     end;
   end;
 end;

theorem Th10:
for L being LATTICE holds
(ex K being full Sublattice of L st M_3,K are_isomorphic) iff
ex a,b,c,d,e being Element of L st
(a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
a"/\"b = a & a"/\"c = a & a"/\"d = a & b"/\"e = b & c"/\"e = c & d"/\"e = d &
  b"/\"c = a & b"/\"d = a & c"/\"d = a & b"\/"c = e & b"\/"d = e & c"\/"d = e)
 proof
  let L be LATTICE;
  set cn = the carrier of M_3;
A1: cn = {0, 1, 2 \ 1 , 3 \ 2, 3} by Def2,YELLOW_1:1;
  then A2: 0 in cn & 1 in cn & 2\1 in cn & 3\2 in cn & 3 in cn by ENUMSET1:24;

  thus (ex K being full Sublattice of L st
  M_3,K are_isomorphic) implies
  ex a,b,c,d,e being Element of L st
(a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
a"/\"b = a & a"/\"c = a & a"/\"d = a & b"/\"e = b & c"/\"e = c & d"/\"e = d &
b"/\"c = a & b"/\"d = a & c"/\"d = a & b"\/"c = e & b"\/"d = e & c"\/"d = e)
   proof
    given K being full Sublattice of L such that
A3:  M_3,K are_isomorphic;
    consider f being map of M_3,K such that
A4:  f is isomorphic by A3,WAYBEL_1:def 8;
A5: K is non empty by A4,WAYBEL_0:def 38;
    reconsider K as non empty SubRelStr of L by A4,WAYBEL_0:def 38;
A6: f is one-to-one monotone by A4,A5,WAYBEL_0:def 38;
    reconsider z = 0 as Element of M_3 by A2;
    reconsider j = 1 as Element of M_3 by A2;
    reconsider dj = 2\1 as Element of M_3 by A2;
    reconsider td = 3\2 as Element of M_3 by A2;
    reconsider t = 3 as Element of M_3 by A2;
    reconsider cl = the carrier of L as non empty set;
    reconsider ck = the carrier of K as non empty set;
A7: ck = rng f by A4,WAYBEL_0:66;
    reconsider g=f as Function of cn,ck;
    reconsider a=g.z,b=g.j,c =g.dj,d=g.td,e=g.t as Element of K
                                      ;
    reconsider ck as non empty Subset of cl by YELLOW_0:def 13;
      a in ck & b in ck & c in ck & d in ck & e in ck;
    then reconsider A=a,B=b,C=c,D=d,E=e as Element of L;
    take A,B,C,D,E;
    thus A<>B by A6,WAYBEL_1:def 1;
    thus A<>C by A6,Th2,WAYBEL_1:def 1;
    thus A<>D by A6,Th4,WAYBEL_1:def 1;
    thus A<>E by A6,WAYBEL_1:def 1;
      now
     assume f.j = f.dj;
     then j = dj by A5,A6,WAYBEL_1:def 1;
     then 1 in 1 by Th2,TARSKI:def 1;
     hence contradiction;
    end;
    hence B<>C;
      now
     assume f.j = f.td;
     then A8:   j = td by A5,A6,WAYBEL_1:def 1;
       0 in j & 0 <> 2 by CARD_5:1,TARSKI:def 1;
     hence contradiction by A8,Th4,TARSKI:def 1;
    end;
    hence B<>D;
    thus B<>E by A6,WAYBEL_1:def 1;
      now
     assume f.dj = f.td;
     then A9:   dj = td by A5,A6,WAYBEL_1:def 1;
       1 in dj & 1 <> 2 by Th2,TARSKI:def 1;
     hence contradiction by A9,Th4,TARSKI:def 1;
    end;
    hence C<>D;
      now
     assume f.dj = f.t;
     then A10:   dj = t by A5,A6,WAYBEL_1:def 1;
       0 in t & 0 <> 1 by Th1,ENUMSET1:14;
     hence contradiction by A10,Th2,TARSKI:def 1;
    end;
    hence C<>E;
      now
     assume f.td = f.t;
     then A11:   td = t by A5,A6,WAYBEL_1:def 1;
       0 in t & 0 <> 2 by Th1,ENUMSET1:14;
     hence contradiction by A11,Th4,TARSKI:def 1;
    end;
    hence D<>E;
A12: {0, 1, 2 \ 1 , 3 \ 2, 3} is non empty by ENUMSET1:24;
      z c= j by XBOOLE_1:2;
    then z <= j by A12,Def2,YELLOW_1:3;
    then a <= b by A4,WAYBEL_0:66;
    then A <= B by YELLOW_0:60;
    hence A "/\" B = A by YELLOW_0:25;
      z c= dj by XBOOLE_1:2;
    then z <= dj by A12,Def2,YELLOW_1:3;
    then a <= c by A4,WAYBEL_0:66;
    then A <= C by YELLOW_0:60;
    hence A "/\" C = A by YELLOW_0:25;

      z c= td by XBOOLE_1:2;
    then z <= td by A12,Def2,YELLOW_1:3;
    then a <= d by A4,WAYBEL_0:66;
    then A <= D by YELLOW_0:60;
    hence A "/\" D = A by YELLOW_0:25;

      j c= t by CARD_1:56;
    then j <= t by A12,Def2,YELLOW_1:3;
    then b <= e by A4,WAYBEL_0:66;
    then B <= E by YELLOW_0:60;
    hence B "/\" E = B by YELLOW_0:25;

      dj c= t
     proof
      let x be set;
      assume x in dj; then x=1 by Th2,TARSKI:def 1;
      hence thesis by Th1,ENUMSET1:14;
     end;
    then dj <= t by A12,Def2,YELLOW_1:3;
    then c <= e by A4,WAYBEL_0:66;
    then C <= E by YELLOW_0:60;
    hence C"/\"E = C by YELLOW_0:25;

      td c= t
     proof
      let x be set;
      assume x in td; then x=2 by Th4,TARSKI:def 1;
      hence thesis by Th1,ENUMSET1:14;
     end;
    then td <= t by A12,Def2,YELLOW_1:3;
    then d <= e by A4,WAYBEL_0:66;
    then D <= E by YELLOW_0:60;
    hence D"/\"E = D by YELLOW_0:25;

    thus B"/\"C = A
     proof
        B in the carrier of K & C in the carrier of K & ex_inf_of {B,C},L
                                  by YELLOW_0:21;
      then inf{B,C} in the carrier of K by YELLOW_0:def 16;
      then B"/\"C in rng f by A7,YELLOW_0:40;
      then consider x being set such that
A13:    x in dom f & B"/\"C = f.x by FUNCT_1:def 5;
        f is Function of the carrier of M_3,the carrier of K;
      then dom f = the carrier of M_3 by FUNCT_2:def 1;
      then reconsider x as Element of M_3 by A13;
A14:      x = z or x = j or x = dj or x = td or x = t by A1,ENUMSET1:23;
A15:    now
       assume B"/\"C = B;
       then B <= C by YELLOW_0:25;
       then b <= c by YELLOW_0:61;
       then j <= dj by A4,WAYBEL_0:66;
       then A16:    j c= dj by A12,Def2,YELLOW_1:3;
         0 in j by CARD_5:1,TARSKI:def 1;
       hence contradiction by A16,Th2,TARSKI:def 1;
      end;
A17:    now
       assume B"/\"C = C;
       then C <= B by YELLOW_0:25;
       then c <= b by YELLOW_0:61;
       then dj <= j by A4,WAYBEL_0:66;
       then A18:    dj c= j by A12,Def2,YELLOW_1:3;
         1 in dj & 0 <> 1 by Th2,TARSKI:def 1;
       hence contradiction by A18,CARD_5:1,TARSKI:def 1;
      end;
A19:    now
       assume B"/\"C = D;
       then D <= C by YELLOW_0:23;
       then d <= c by YELLOW_0:61;
       then td <= dj by A4,WAYBEL_0:66;
       then A20:    td c= dj by A12,Def2,YELLOW_1:3;
         2 in td by Th4,TARSKI:def 1;
       hence contradiction by A20,Th2,TARSKI:def 1;
      end;
        now
       assume B"/\"C = E;
       then E <= C by YELLOW_0:23;
       then e <= c by YELLOW_0:61;
       then t <= dj by A4,WAYBEL_0:66;
       then A21:    t c= dj by A12,Def2,YELLOW_1:3;
         2 in t by Th1,ENUMSET1:14;
       hence contradiction by A21,Th2,TARSKI:def 1;
      end;
      hence thesis by A13,A14,A15,A17,A19;
     end;

    thus B"/\"D = A
     proof
        B in the carrier of K & D in the carrier of K & ex_inf_of {B,D},L
                                  by YELLOW_0:21;
      then inf{B,D} in the carrier of K by YELLOW_0:def 16;
      then B"/\"D in rng f by A7,YELLOW_0:40;
      then consider x being set such that
A22:    x in dom f & B"/\"D = f.x by FUNCT_1:def 5;
        f is Function of the carrier of M_3,the carrier of K;
      then dom f = the carrier of M_3 by FUNCT_2:def 1;
      then reconsider x as Element of M_3 by A22;
A23:      x = z or x = j or x = dj or x = td or x = t by A1,ENUMSET1:23;
A24:    now
       assume B"/\"D = B;
       then B <= D by YELLOW_0:25;
       then b <= d by YELLOW_0:61;
       then j <= td by A4,WAYBEL_0:66;
       then A25:    j c= td by A12,Def2,YELLOW_1:3;
         0 in j by CARD_5:1,TARSKI:def 1;
       hence contradiction by A25,Th4,TARSKI:def 1;
      end;
A26:    now
       assume B"/\"D = C;
       then C <= B by YELLOW_0:23;
       then c <= b by YELLOW_0:61;
       then dj <= j by A4,WAYBEL_0:66;
       then A27:    dj c= j by A12,Def2,YELLOW_1:3;
         1 in dj & 0 <> 1 by Th2,TARSKI:def 1;
       hence contradiction by A27,CARD_5:1,TARSKI:def 1;
      end;
A28:    now
       assume B"/\"D = D;
       then D <= B by YELLOW_0:23;
       then d <= b by YELLOW_0:61;
       then td <= j by A4,WAYBEL_0:66;
       then A29:    td c= j by A12,Def2,YELLOW_1:3;
         2 in td by Th4,TARSKI:def 1;
       hence contradiction by A29,CARD_5:1,TARSKI:def 1;
      end;
        now
       assume B"/\"D = E;
       then E <= B by YELLOW_0:23;
       then e <= b by YELLOW_0:61;
       then t <= j by A4,WAYBEL_0:66;
       then A30:    t c= j by A12,Def2,YELLOW_1:3;
         2 in t by Th1,ENUMSET1:14;
       hence contradiction by A30,CARD_5:1,TARSKI:def 1;
      end;
      hence thesis by A22,A23,A24,A26,A28;
     end;

    thus C"/\"D = A
     proof
        C in the carrier of K & D in the carrier of K & ex_inf_of {C,D},L
                                  by YELLOW_0:21;
      then inf{C,D} in the carrier of K by YELLOW_0:def 16;
      then C"/\"D in rng f by A7,YELLOW_0:40;
      then consider x being set such that
A31:    x in dom f & C"/\"D = f.x by FUNCT_1:def 5;
        f is Function of the carrier of M_3,the carrier of K;
      then dom f = the carrier of M_3 by FUNCT_2:def 1;
      then reconsider x as Element of M_3 by A31;
A32:      x = z or x = j or x = dj or x = td or x = t by A1,ENUMSET1:23;
A33:    now
       assume C"/\"D = B;
       then B <= C by YELLOW_0:23;
       then b <= c by YELLOW_0:61;
       then j <= dj by A4,WAYBEL_0:66;
       then A34:    j c= dj by A12,Def2,YELLOW_1:3;
         0 in j by CARD_5:1,TARSKI:def 1;
       hence contradiction by A34,Th2,TARSKI:def 1;
      end;
A35:    now
       assume C"/\"D = C;
       then C <= D by YELLOW_0:25;
       then c <= d by YELLOW_0:61;
       then dj <= td by A4,WAYBEL_0:66;
       then A36:    dj c= td by A12,Def2,YELLOW_1:3;
         1 in dj & 1 <> 2 by Th2,TARSKI:def 1;
       hence contradiction by A36,Th4,TARSKI:def 1;
      end;
A37:    now
       assume C"/\"D = D;
       then D <= C by YELLOW_0:23;
       then d <= c by YELLOW_0:61;
       then td <= dj by A4,WAYBEL_0:66;
       then A38:    td c= dj by A12,Def2,YELLOW_1:3;
         2 in td by Th4,TARSKI:def 1;
       hence contradiction by A38,Th2,TARSKI:def 1;
      end;
        now
       assume C"/\"D = E;
       then E <= C by YELLOW_0:23;
       then e <= c by YELLOW_0:61;
       then t <= dj by A4,WAYBEL_0:66;
       then A39:    t c= dj by A12,Def2,YELLOW_1:3;
         2 in t by Th1,ENUMSET1:14;
       hence contradiction by A39,Th2,TARSKI:def 1;
      end;
      hence thesis by A31,A32,A33,A35,A37;
     end;

    thus B"\/"C = E
     proof
        B in the carrier of K & B in the carrier of K & ex_sup_of {B,C},L
                                  by YELLOW_0:20;
      then sup{B,C} in the carrier of K by YELLOW_0:def 17;
      then B"\/"C in rng f by A7,YELLOW_0:41;
      then consider x being set such that
A40:    x in dom f & B"\/"C = f.x by FUNCT_1:def 5;
        f is Function of the carrier of M_3,the carrier of K;
      then dom f = the carrier of M_3 by FUNCT_2:def 1;
      then reconsider x as Element of M_3 by A40;
A41:      x = z or x = j or x = dj or x = td or x = t by A1,ENUMSET1:23;
A42:    now
       assume B"\/"C = B;
       then B >= C by YELLOW_0:24;
       then b >= c by YELLOW_0:61;
       then j >= dj by A4,WAYBEL_0:66;
       then A43:    dj c= j by A12,Def2,YELLOW_1:3;
         1 in dj & 0 <> 1 by Th2,TARSKI:def 1;
       hence contradiction by A43,CARD_5:1,TARSKI:def 1;
      end;
A44:    now
       assume B"\/"C = C;
       then C >= B by YELLOW_0:24;
       then c >= b by YELLOW_0:61;
       then dj >= j by A4,WAYBEL_0:66;
       then A45:    j c= dj by A12,Def2,YELLOW_1:3;
         0 in j by CARD_5:1,TARSKI:def 1;
       hence contradiction by A45,Th2,TARSKI:def 1;
      end;
A46:    now
       assume B"\/"C = D;
       then D >= C by YELLOW_0:22;
       then d >= c by YELLOW_0:61;
       then td >= dj by A4,WAYBEL_0:66;
       then A47:    dj c= td by A12,Def2,YELLOW_1:3;
         1 in dj & 2 <> 1 by Th2,TARSKI:def 1;
       hence contradiction by A47,Th4,TARSKI:def 1;
      end;
        now
       assume B"\/"C = A;
       then A >= C by YELLOW_0:22;
       then a >= c by YELLOW_0:61;
       then z >= dj by A4,WAYBEL_0:66;
       then dj c= z by A12,Def2,YELLOW_1:3;
       hence contradiction by Th2,XBOOLE_1:3;
      end;
      hence thesis by A40,A41,A42,A44,A46;
     end;

    thus B"\/"D = E
     proof
        B in the carrier of K & D in the carrier of K & ex_sup_of {B,D},L
                                  by YELLOW_0:20;
      then sup{B,D} in the carrier of K by YELLOW_0:def 17;
      then B"\/"D in rng f by A7,YELLOW_0:41;
      then consider x being set such that
A48:    x in dom f & B"\/"D = f.x by FUNCT_1:def 5;
        f is Function of the carrier of M_3,the carrier of K;
      then dom f = the carrier of M_3 by FUNCT_2:def 1;
      then reconsider x as Element of M_3 by A48;
A49:      x = z or x = j or x = dj or x = td or x = t by A1,ENUMSET1:23;
A50:    now
       assume B"\/"D = B;
       then B >= D by YELLOW_0:22;
       then b >= d by YELLOW_0:61;
       then j >= td by A4,WAYBEL_0:66;
       then A51:    td c= j by A12,Def2,YELLOW_1:3;
         2 in td & 2 <> 0 by Th4,TARSKI:def 1;
       hence contradiction by A51,CARD_5:1,TARSKI:def 1;
      end;
A52:    now
       assume B"\/"D = C;
       then C >= D by YELLOW_0:22;
       then c >= d by YELLOW_0:61;
       then dj >= td by A4,WAYBEL_0:66;
       then A53:    td c= dj by A12,Def2,YELLOW_1:3;
         2 in td & 2 <> 1 by Th4,TARSKI:def 1;
       hence contradiction by A53,Th2,TARSKI:def 1;
      end;
A54:    now
       assume B"\/"D = D;
       then D >= B by YELLOW_0:22;
       then d >= b by YELLOW_0:61;
       then td >= j by A4,WAYBEL_0:66;
       then A55:    j c= td by A12,Def2,YELLOW_1:3;
         0 in j & 0 <> 2 by CARD_5:1,TARSKI:def 1;
       hence contradiction by A55,Th4,TARSKI:def 1;
      end;
        now
       assume B"\/"D = A;
       then A >= B by YELLOW_0:22;
       then a >= b by YELLOW_0:61;
       then z >= j by A4,WAYBEL_0:66;
       then j c= z by A12,Def2,YELLOW_1:3;
       hence contradiction by XBOOLE_1:3;
      end;
      hence thesis by A48,A49,A50,A52,A54;
     end;

    thus C"\/"D = E
     proof
        C in the carrier of K & D in the carrier of K & ex_sup_of {C,D},L
                                  by YELLOW_0:20;
      then sup{C,D} in the carrier of K by YELLOW_0:def 17;
      then C"\/"D in rng f by A7,YELLOW_0:41;
      then consider x being set such that
A56:    x in dom f & C"\/"D = f.x by FUNCT_1:def 5;
        f is Function of the carrier of M_3,the carrier of K;
      then dom f = the carrier of M_3 by FUNCT_2:def 1;
      then reconsider x as Element of M_3 by A56;
A57:      x = z or x = j or x = dj or x = td or x = t by A1,ENUMSET1:23;
A58:    now
       assume C"\/"D = B;
       then B >= C by YELLOW_0:22;
       then b >= c by YELLOW_0:61;
       then j >= dj by A4,WAYBEL_0:66;
       then A59:    dj c= j by A12,Def2,YELLOW_1:3;
         1 in dj by Th2,TARSKI:def 1;
       then 1 in 1 by A59;
       hence contradiction;
      end;
A60:    now
       assume C"\/"D = C;
       then C >= D by YELLOW_0:24;
       then c >= d by YELLOW_0:61;
       then dj >= td by A4,WAYBEL_0:66;
       then A61:    td c= dj by A12,Def2,YELLOW_1:3;
         2 in td & 2 <> 1 by Th4,TARSKI:def 1;
       hence contradiction by A61,Th2,TARSKI:def 1;
      end;
A62:    now
       assume C"\/"D = D;
       then D >= C by YELLOW_0:22;
       then d >= c by YELLOW_0:61;
       then td >= dj by A4,WAYBEL_0:66;
       then A63:    dj c= td by A12,Def2,YELLOW_1:3;
         1 in dj & 1 <> 2 by Th2,TARSKI:def 1;
       hence contradiction by A63,Th4,TARSKI:def 1;
      end;
        now
       assume C"\/"D = A;
       then A >= C by YELLOW_0:22;
       then a >= c by YELLOW_0:61;
       then z >= dj by A4,WAYBEL_0:66;
       then dj c= z by A12,Def2,YELLOW_1:3;
       hence contradiction by Th2,XBOOLE_1:3;
      end;
      hence thesis by A56,A57,A58,A60,A62;
     end;

   end;
  thus (ex a,b,c,d,e being Element of L st
  (a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
  a"/\"b = a & a"/\"c = a & a"/\"d = a & b"/\"e = b & c"/\"e = c & d"/\"e = d &
  b"/\"c = a & b"/\"d = a & c"/\"d = a & b"\/"c = e & b"\/"d = e & c"\/"
d = e)) implies
  ex K being full Sublattice of L st
  M_3,K are_isomorphic
   proof
    given a,b,c,d,e being Element of L such that
A64:  a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
    a"/\"b = a & a"/\"c = a & a"/\"d = a & b"/\"e = b & c"/\"e = c & d"/\"
e = d &
    b"/\"c = a & b"/\"d = a & c"/\"d = a & b"\/"c = e & b"\/"d = e & c"\/"
d = e;

    set ck = {a,b,c,d,e};
      now
     let x be set;
     assume x in ck;
     then x=a or x=b or x=c or x=d or x=e by ENUMSET1:23;
     hence x in the carrier of L;
    end;
    then reconsider ck as Subset of L by TARSKI:def 3;
    set K = subrelstr ck;
A65: the carrier of K = ck by YELLOW_0:def 15;
A66:    a in ck by ENUMSET1:24;
A67:  K is meet-inheriting
     proof
      let x,y be Element of L;
      assume
A68:      x in the carrier of K & y in the carrier of K & ex_inf_of {x,y},L;
      per cases by A65,A68,ENUMSET1:23;
      suppose x=a & y=a;
      then inf{x,y} = a"/\"a by YELLOW_0:40;
      then inf{x,y} = a by YELLOW_5:2;
      hence thesis by A65,ENUMSET1:24;
      suppose x=a & y=b;
      then inf{x,y} = a"/\"b by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=a & y=c;
      then inf{x,y} = a"/\"c by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=a & y=d;
      then inf{x,y} = a"/\"d by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose
A69:    x=a & y=e;
        a <= c & c <= e by A64,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then inf {x,y} = a by A69,YELLOW_0:40;
      hence thesis by A65,ENUMSET1:24;
      suppose x=b & y=a;
      then inf{x,y} = a"/\"b by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=b & y=b;
      then inf{x,y} = b"/\"b by YELLOW_0:40;
      then inf{x,y} = b by YELLOW_5:2;
      hence thesis by A65,ENUMSET1:24;
      suppose x=b & y=c;
      then inf{x,y} = b"/\"c by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=b & y=d;
      then inf{x,y} = b"/\"d by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=b & y=e;
      then inf{x,y} = b"/\"e by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=c & y=a;
      then inf{x,y} = a"/\"c by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=c & y=b;
      then inf{x,y} = b"/\"c by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=c & y=c;
      then inf{x,y} = c"/\"c by YELLOW_0:40;
      then inf{x,y} = c by YELLOW_5:2;
      hence thesis by A65,ENUMSET1:24;
      suppose x=c & y=d;
      then inf{x,y} = c"/\"d by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=c & y=e;
      then inf{x,y} = c"/\"e by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=d & y=a;
      then inf{x,y} = a"/\"d by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=d & y=b;
      then inf{x,y} = b"/\"d by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=d & y=c;
      then inf{x,y} = c"/\"d by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=d & y=d;
      then inf{x,y} = d"/\"d by YELLOW_0:40;
      then inf{x,y} = d by YELLOW_5:2;
      hence thesis by A65,ENUMSET1:24;
      suppose x=d & y=e;
      then inf{x,y} = d"/\"e by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose
A70:    x=e & y=a;
        a <= c & c <= e by A64,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then inf {x,y} = a by A70,YELLOW_0:40;
      hence thesis by A65,ENUMSET1:24;
      suppose x=e & y=b;
      then inf{x,y} = b"/\"e by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=e & y=c;
      then inf{x,y} = c"/\"e by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=e & y=d;
      then inf{x,y} = d"/\"e by YELLOW_0:40;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=e & y=e;
      then inf{x,y} = e"/\"e by YELLOW_0:40;
      then inf{x,y} = e by YELLOW_5:2;
      hence thesis by A65,ENUMSET1:24;
     end;

      K is join-inheriting
     proof
      let x,y be Element of L;
      assume
A71:      x in the carrier of K & y in the carrier of K & ex_sup_of {x,y},L;
      per cases by A65,A71,ENUMSET1:23;
      suppose x=a & y=a;
      then sup{x,y} = a"\/"a by YELLOW_0:41;
      then sup{x,y} = a by YELLOW_5:1;
      hence thesis by A65,ENUMSET1:24;
      suppose x=a & y=b;
      then x"\/"y = b by A64,Th5;
      then sup{x,y} = b by YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose x=a & y=c;
      then x"\/"y = c by A64,Th5;
      then sup{x,y} = c by YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose x=a & y=d;
      then x"\/"y = d by A64,Th5;
      then sup{x,y} = d by YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose
A72:    x=a & y=e;
        a <= c & c <= e by A64,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then a"\/"e = e by Th5;
      then sup {x,y} = e by A72,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose
A73:    x=b & y=a;
        a"\/"b = b by A64,Th5;
      then sup{x,y} = b by A73,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose x=b & y=b;
      then sup{x,y} = b"\/"b by YELLOW_0:41;
      then sup{x,y} = b by YELLOW_5:1;
      hence thesis by A65,ENUMSET1:24;
      suppose x=b & y=c;
      then sup{x,y} = b"\/"c by YELLOW_0:41;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=b & y=d;
      then sup{x,y} = b"\/"d by YELLOW_0:41;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose
A74:    x=b & y=e;
        b"\/"e = e by A64,Th5;
      then sup{x,y} = e by A74,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose
A75:    x=c & y=a;
        c"\/"a = c by A64,Th5;
      then sup{x,y} = c by A75,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose x=c & y=b;
      then sup{x,y} = b"\/"c by YELLOW_0:41;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=c & y=c;
      then sup{x,y} = c"\/"c by YELLOW_0:41;
      then sup{x,y} = c by YELLOW_5:1;
      hence thesis by A65,ENUMSET1:24;
      suppose x=c & y=d;
      then sup{x,y} = c"\/"d by YELLOW_0:41;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose
A76:    x=c & y=e;
        c"\/"e = e by A64,Th5;
      then sup{x,y} = e by A76,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose x=d & y=a;
      then x"\/"y = d by A64,Th5;
      then sup{x,y} = d by YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose x=d & y=b;
      then sup{x,y} = b"\/"d by YELLOW_0:41;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=d & y=c;
      then sup{x,y} = c"\/"d by YELLOW_0:41;
      hence thesis by A64,A65,ENUMSET1:24;
      suppose x=d & y=d;
      then sup{x,y} = d"\/"d by YELLOW_0:41;
      then sup{x,y} = d by YELLOW_5:1;
      hence thesis by A65,ENUMSET1:24;
      suppose
A77:    x=d & y=e;
        d"\/"e = e by A64,Th5;
      then sup{x,y} = e by A77,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose
A78:    x=e & y=a;
        a <= c & c <= e by A64,YELLOW_0:25;
      then a <= e by ORDERS_1:26;
      then a"/\"e = a by YELLOW_0:25;
      then a"\/"e = e by Th5;
      then sup {x,y} = e by A78,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose
A79:    x=e & y=b;
        b"\/"e = e by A64,Th5;
      then sup{x,y} = e by A79,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose
A80:    x=e & y=c;
        c"\/"e = e by A64,Th5;
      then sup{x,y} = e by A80,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose
A81:    x=e & y=d;
        d"\/"e = e by A64,Th5;
      then sup{x,y} = e by A81,YELLOW_0:41;
      hence thesis by A65,ENUMSET1:24;
      suppose x=e & y=e;
      then sup{x,y} = e"\/"e by YELLOW_0:41;
      then sup{x,y} = e by YELLOW_5:1;
      hence thesis by A65,ENUMSET1:24;
     end;
    then reconsider K as non empty full Sublattice of L
         by A65,A66,A67,STRUCT_0:def 1;
    take K;
    thus M_3,K are_isomorphic
     proof
      reconsider z = 0 as Element of M_3 by A2;
      reconsider j = 1 as Element of M_3 by A2;
      reconsider dj = 2\1 as Element of M_3 by A2;
      reconsider td = 3\2 as Element of M_3 by A2;
      reconsider t = 3 as Element of M_3 by A2;

A82:  now
       assume
    A83: j=dj;
         1 in dj by Th2,TARSKI:def 1;
       hence contradiction by A83;
      end;
A84: now
       assume
    A85: j=td;
         2 in td & 0 <> 2 by Th4,TARSKI:def 1;
       hence contradiction by A85,CARD_5:1,TARSKI:def 1;
      end;
A86: now
       assume
    A87: dj=td;
         2 in td & 1 <> 2 by Th4,TARSKI:def 1;
       hence contradiction by A87,Th2,TARSKI:def 1;
      end;
A88:  now
       assume
    A89: dj=t;
         2 in t & 1 <> 2 by Th1,ENUMSET1:14;
       hence contradiction by A89,Th2,TARSKI:def 1;
      end;
A90:  now
       assume
    A91: td=t;
         0 in t & 0 <> 2 by Th1,ENUMSET1:14;
       hence contradiction by A91,Th4,TARSKI:def 1;
      end;

      defpred P[set,set] means
      for X being Element of M_3 st X=$1 holds
     ((X = z implies $2 = a) &
      (X = j implies $2 = b) &
      (X = dj implies $2 = c) &
      (X = td implies $2 = d) &
      (X = t implies $2 = e));

A92:   for x being set st x in cn ex y being set st y in ck & P[x,y]
       proof
        let x be set;
        assume
A93:         x in cn;
        per cases by A1,A93,ENUMSET1:23;
        suppose
A94:      x = 0;
        take y=a;
        thus y in ck by ENUMSET1:24;
        let X be Element of M_3;
        thus thesis by A94,Th2,Th4;
        suppose
A95:      x=1;
        take y=b;
        thus y in ck by ENUMSET1:24;
        let X be Element of M_3;
        thus thesis by A82,A84,A95;
        suppose
A96:      x = 2\1;
        take y=c;
        thus y in ck by ENUMSET1:24;
        let X be Element of M_3;
        thus thesis by A82,A86,A88,A96,Th2;
        suppose
A97:      x = 3 \ 2;
        take y=d;
        thus y in ck by ENUMSET1:24;
        let X be Element of M_3;
        thus thesis by A84,A86,A90,A97,Th4;
        suppose
A98:      x = 3;
        take y=e;
        thus y in ck by ENUMSET1:24;
        let X be Element of M_3;
        thus thesis by A88,A90,A98;
       end;

      consider f being Function of cn,ck such that
A99:    for x being set st x in cn holds P[x,f.x] from FuncEx1(A92);
      reconsider f as map of M_3,K by A65;
      take f;
A100:  f is one-to-one
       proof
          now
         let x,y be Element of M_3;
         assume
A101:      f.x = f.y;
         thus x=y
          proof
           per cases by A1,ENUMSET1:23;
           suppose x = z & y = z;hence thesis;
           suppose x = j & y = j;hence thesis;
           suppose x = dj & y = dj;hence thesis;
           suppose x = td & y = td;hence thesis;
           suppose x = t & y = t;hence thesis;
           suppose x = z & y = j;
           then f.x=a & f.y=b by A99;
           hence thesis by A64,A101;
           suppose x = z & y = dj;
           then f.x=a & f.y=c by A99;
           hence thesis by A64,A101;
           suppose x = z & y = td;
           then f.x=a & f.y=d by A99;
           hence thesis by A64,A101;
           suppose x = z & y = t;
           then f.x=a & f.y=e by A99;
           hence thesis by A64,A101;
           suppose x = j & y = z;
           then f.x=b & f.y=a by A99;
           hence thesis by A64,A101;
           suppose x = j & y = dj;
           then f.x=b & f.y=c by A99;
           hence thesis by A64,A101;
           suppose x = j & y = td;
           then f.x=b & f.y=d by A99;
           hence thesis by A64,A101;
           suppose x = j & y = t;
           then f.x=b & f.y=e by A99;
           hence thesis by A64,A101;
           suppose x = dj & y = z;
           then f.x=c & f.y=a by A99;
           hence thesis by A64,A101;
           suppose x = dj & y = j;
           then f.x=c & f.y=b by A99;
           hence thesis by A64,A101;
           suppose x = dj & y = td;
           then f.x=c & f.y=d by A99;
           hence thesis by A64,A101;
           suppose x = dj & y = t;
           then f.x=c & f.y=e by A99;
           hence thesis by A64,A101;
           suppose x = td & y = z;
           then f.x=d & f.y=a by A99;
           hence thesis by A64,A101;
           suppose x = td & y = j;
           then f.x=d & f.y=b by A99;
           hence thesis by A64,A101;
           suppose x = td & y = dj;
           then f.x=d & f.y=c by A99;
           hence thesis by A64,A101;
           suppose x = td & y = t;
           then f.x=d & f.y=e by A99;
           hence thesis by A64,A101;
           suppose x = t & y = z;
           then f.x=e & f.y=a by A99;
           hence thesis by A64,A101;
           suppose x = t & y = j;
           then f.x=e & f.y=b by A99;
           hence thesis by A64,A101;
           suppose x = t & y = dj;
           then f.x=e & f.y=c by A99;
           hence thesis by A64,A101;
           suppose x = t & y = td;
           then f.x=e & f.y=d by A99;
           hence thesis by A64,A101;
          end;
        end;
        hence thesis by WAYBEL_1:def 1;
       end;
A102: dom f = the carrier of M_3 by FUNCT_2:def 1;
A103: rng f = ck
       proof
        thus rng f c= ck
         proof
          let y be set;
          assume y in rng f;
          then consider x being set such that
A104:        x in dom f & y=f.x by FUNCT_1:def 5;
            x in the carrier of M_3 by A104,FUNCT_2:def 1;
          then reconsider x as Element of M_3;
            (x = z or x = j or x = dj or x = td or x = t) by A1,ENUMSET1:23;
          then y=a or y=d or y=c or y=b or y=e by A99,A104;
          hence thesis by ENUMSET1:24;
         end;
        thus ck c= rng f
         proof
          let y be set;
          assume
A105:          y in ck;
          per cases by A105,ENUMSET1:23;
          suppose
A106:        y=a;
            z in dom f & a = f.z by A99,A102;
          hence y in rng f by A106,FUNCT_1:def 5;
          suppose
A107:        y=b;
            j in dom f & b=f.j by A99,A102;
          hence y in rng f by A107,FUNCT_1:def 5;
          suppose
A108:        y=c;
            dj in dom f & c = f.dj by A99,A102;
          hence y in rng f by A108,FUNCT_1:def 5;
          suppose
A109:        y=d;
            td in dom f & d=f.td by A99,A102;
          hence y in rng f by A109,FUNCT_1:def 5;
          suppose
A110:        y=e;
            t in dom f & e=f.t by A99,A102;
          hence y in rng f by A110,FUNCT_1:def 5;
         end;
       end;

        for x,y being Element of M_3 holds x <= y iff f.x <= f.y
       proof
        let x,y be Element of M_3;
A111:     {0, 1, 2\1, 3 \ 2, 3} is non empty by ENUMSET1:24;
        thus x <= y implies f.x <= f.y
         proof
          assume
A112:       x <= y;
          per cases by A1,ENUMSET1:23;
          suppose x=z & y=z;hence thesis;
          suppose x=z & y=j;
          then A113:       f.x = a & f.y = b by A99;
            a in the carrier of K & b in the carrier of K by A65,ENUMSET1:24;
          then reconsider A=a,B=b as Element of K;
            a <= b & A in the carrier of K & B in the carrier of K
                                          by A64,YELLOW_0:25;
          hence f.x <= f.y by A113,YELLOW_0:61;
          suppose x=z & y=dj;
          then A114:       f.x = a & f.y = c by A99;
            a in the carrier of K & c in the carrier of K by A65,ENUMSET1:24;
          then reconsider A=a,C=c as Element of K;
            a <= c & A in the carrier of K & C in the carrier of K
                                          by A64,YELLOW_0:25;
          hence f.x <= f.y by A114,YELLOW_0:61;
          suppose x=z & y=td;
          then A115:       f.x = a & f.y = d by A99;
            a in the carrier of K & d in the carrier of K by A65,ENUMSET1:24;
          then reconsider A=a,D=d as Element of K;
            a <= d & A in the carrier of K & D in the carrier of K
                                          by A64,YELLOW_0:25;
          hence f.x <= f.y by A115,YELLOW_0:61;
          suppose x=z & y=t;
          then A116:       f.x = a & f.y = e by A99;
            a in the carrier of K & e in the carrier of K by A65,ENUMSET1:24;
          then reconsider A=a,E=e as Element of K;
            a <= c & c <= e by A64,YELLOW_0:25;
          then a <= e & A in the carrier of K & E in the carrier of K
                                          by ORDERS_1:26;
          hence f.x <= f.y by A116,YELLOW_0:61;
          suppose x=j & y=z;
          then j c= z by A111,A112,Def2,YELLOW_1:3;
          hence thesis by XBOOLE_1:3;
          suppose x=j & y=j;hence thesis;
          suppose
A117:        x=j & y=dj;
            0 in j & not 0 in dj by Th2,CARD_5:1,TARSKI:def 1;
          then not j c= dj;
          hence thesis by A111,A112,A117,Def2,YELLOW_1:3;
          suppose
A118:        x=j & y=td;
            0 in j & not 0 in td by Th4,CARD_5:1,TARSKI:def 1;
          then not j c= td;
          hence thesis by A111,A112,A118,Def2,YELLOW_1:3;
          suppose x=j & y=t;
          then A119:       f.x = b & f.y = e by A99;
            b in the carrier of K & e in the carrier of K by A65,ENUMSET1:24;
          then reconsider B=b,E=e as Element of K;
            b <= e & B in the carrier of K & E in the carrier of K
                                          by A64,YELLOW_0:25;
          hence f.x <= f.y by A119,YELLOW_0:61;
          suppose x=dj & y=z;
          then dj c= z by A111,A112,Def2,YELLOW_1:3;
          hence thesis by Th2,XBOOLE_1:3;
          suppose
A120:        x=dj & y=j;
            1 in dj & not 1 in j by Th2,TARSKI:def 1;
          then not dj c= j;
          hence thesis by A111,A112,A120,Def2,YELLOW_1:3;
          suppose x=dj & y=dj;hence thesis;
          suppose
A121:        x=dj & y=td;
            1 in dj & not 1 in td by Th2,Th4,TARSKI:def 1;
          then not dj c= td;
          hence thesis by A111,A112,A121,Def2,YELLOW_1:3;
          suppose x=dj & y=t;
          then A122:       f.x = c & f.y = e by A99;
            c in the carrier of K & e in the carrier of K by A65,ENUMSET1:24;
          then reconsider C=c,E=e as Element of K;
            c <= e & C in the carrier of K & E in the carrier of K
                                          by A64,YELLOW_0:25;
          hence f.x <= f.y by A122,YELLOW_0:61;
          suppose x=td & y=z;
          then td c= z by A111,A112,Def2,YELLOW_1:3;
          hence thesis by Th4,XBOOLE_1:3;
          suppose
A123:        x=td & y=j;
            2 in td & not 2 in j by Th4,CARD_5:1,TARSKI:def 1;
          then not td c= j;
          hence thesis by A111,A112,A123,Def2,YELLOW_1:3;
          suppose
A124:        x=td & y=dj;
            2 in td & not 2 in dj by Th2,Th4,TARSKI:def 1;
          then not td c= dj;
          hence thesis by A111,A112,A124,Def2,YELLOW_1:3;
          suppose x=td & y=td;hence thesis;
          suppose x=td & y=t;
          then A125:       f.x = d & f.y = e by A99;
            d in the carrier of K & e in the carrier of K by A65,ENUMSET1:24;
          then reconsider D=d,E=e as Element of K;
            d <= e & D in the carrier of K & E in the carrier of K
                                          by A64,YELLOW_0:25;
          hence f.x <= f.y by A125,YELLOW_0:61;
          suppose x=t & y=z;
          then t c= z by A111,A112,Def2,YELLOW_1:3;
          hence thesis by XBOOLE_1:3;
          suppose
A126:        x=t & y=j;
            1 in t & not 1 in j by Th1,ENUMSET1:14;
          then not t c= j;
          hence thesis by A111,A112,A126,Def2,YELLOW_1:3;
          suppose
A127:        x=t & y=dj;
            2 in t & not 2 in dj by Th1,Th2,ENUMSET1:14,TARSKI:def 1;
          then not t c= dj;
          hence thesis by A111,A112,A127,Def2,YELLOW_1:3;
          suppose
A128:        x=t & y=td;
            0 in t & not 0 in td by Th1,Th4,ENUMSET1:14,TARSKI:def 1;
          then not t c= td;
          hence thesis by A111,A112,A128,Def2,YELLOW_1:3;
          suppose x=t & y=t;hence thesis;
         end;
        thus f.x <= f.y implies x <= y
         proof
          assume
A129:       f.x <= f.y;
A130:          f.x in ck & f.y in ck by A102,A103,FUNCT_1:def 5;
A131:     dj c= t
           proof
            let X be set;assume X in dj; then X=1 by Th2,TARSKI:def 1;
            hence thesis by Th1,ENUMSET1:14;
           end;
A132:     td c= t
           proof
            let X be set;assume X in td; then X=2 by Th4,TARSKI:def 1;
            hence thesis by Th1,ENUMSET1:14;
           end;
          per cases by A130,ENUMSET1:23;
          suppose f.x = a & f.y = a;
          hence x <= y by A100,WAYBEL_1:def 1;
          suppose A133: f.x = a & f.y = b;
            f.z = a & f.j = b by A99;
          then z=x & j = y by A100,A133,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A111,Def2,YELLOW_1:3;
          suppose A134: f.x = a & f.y = c;
            f.z = a & f.dj = c by A99;
          then z=x & dj = y by A100,A134,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A111,Def2,YELLOW_1:3;
          suppose A135: f.x = a & f.y = d;
            f.z = a & f.td = d by A99;
          then z=x & td = y by A100,A135,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A111,Def2,YELLOW_1:3;
          suppose A136: f.x = a & f.y = e;
            f.z = a & f.t = e by A99;
          then z=x & t = y by A100,A136,WAYBEL_1:def 1;
          then x c= y by XBOOLE_1:2;
          hence x <= y by A111,Def2,YELLOW_1:3;
          suppose f.x = b & f.y = a;
          then b <= a by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = b & f.y = b;
          hence x <= y by A100,WAYBEL_1:def 1;
          suppose f.x = b & f.y = c;
          then b <= c by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = b & f.y = d;
          then b <= d by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose A137: f.x = b & f.y = e;
            f.j = b & f.t = e by A99;
          then j=x & t = y by A100,A137,WAYBEL_1:def 1;
          then x c= y by CARD_1:56;
          hence x <= y by A111,Def2,YELLOW_1:3;
          suppose f.x = c & f.y = a;
          then c <= a by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = c & f.y = b;
          then c <= b by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = c & f.y = c;
          hence x <= y by A100,WAYBEL_1:def 1;
          suppose f.x = c & f.y = d;
          then c <= d by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose A138: f.x = c & f.y = e;
            f.dj = c & f.t = e by A99;
          then dj = x & t = y by A100,A138,WAYBEL_1:def 1;
          hence x <= y by A111,A131,Def2,YELLOW_1:3;
          suppose f.x = d & f.y = a;
          then d <= a & a <= b by A64,A129,YELLOW_0:25,60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = d & f.y = b;
          then d <= b by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = d & f.y = c;
          then d <= c by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = d & f.y = d;
          hence x <= y by A100,WAYBEL_1:def 1;
          suppose A139: f.x = d & f.y = e;
            f.td = d & f.t = e by A99;
          then td=x & t = y by A100,A139,WAYBEL_1:def 1;
          hence x <= y by A111,A132,Def2,YELLOW_1:3;
          suppose f.x = e & f.y = a;
          then e <= a & a <= b by A64,A129,YELLOW_0:25,60;
          then e <= b by ORDERS_1:26;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = e & f.y = b;
          then e <= b by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = e & f.y = c;
          then e <= c by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = e & f.y = d;
          then e <= d by A129,YELLOW_0:60;
          hence x <= y by A64,YELLOW_0:25;
          suppose f.x = e & f.y = e;
          hence x <= y by A100,WAYBEL_1:def 1;
         end;
      end;
      hence f is isomorphic by A65,A100,A103,WAYBEL_0:66;
     end;
   end;
 end;

begin:: Modular lattices

definition
 let L be non empty RelStr;
 attr L is modular means :Def3:
 for a,b,c being Element of L st a <= c holds a"\/"(b"/\"c) = (a"\/"b)"/\"c;
end;

definition
 cluster distributive -> modular
 (non empty antisymmetric reflexive with_infima RelStr);
 coherence
  proof
   let L be non empty antisymmetric reflexive with_infima RelStr;
   assume
A1: L is distributive;
     now
    let a,b,c be Element of L;
    assume a <= c;
    hence a"\/"(b"/\"c) = (a"/\"c)"\/"(b"/\"c) by YELLOW_0:25
                   .= (a"\/"b)"/\"c by A1,WAYBEL_1:def 3;
   end;
   hence L is modular by Def3;
  end;
end;

Lm2:
for L being LATTICE holds
L is modular iff not ex a,b,c,d,e being Element of L st
(a<>b & a<>c & a<>d & a<>e & b<>c & b<>d & b<>e & c <>d & c <>e & d<>e &
a"/\"b = a & a"/\"c = a & c"/\"e = c & d"/\"e = d &
b&qu