LATTICE8

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:: J\'onsson Theorem about Representation of Modular Lattices
::  by Mariusz {\L}api\'nski
::
:: Received June 29, 2000
:: Copyright (c) 2000-2026 Association of Mizar Users
::           (Stowarzyszenie Uzytkownikow Mizara, Bialystok, Poland).
:: This code can be distributed under the GNU General Public Licence
:: version 3.0 or later, or the Creative Commons Attribution-ShareAlike
:: License version 3.0 or later, subject to the binding interpretation
:: detailed in file COPYING.interpretation.
:: See COPYING.GPL and COPYING.CC-BY-SA for the full text of these
:: licenses, or see http://www.gnu.org/licenses/gpl.html and
:: http://creativecommons.org/licenses/by-sa/3.0/.

environ

 vocabularies NUMBERS, ORDERS_2, XBOOLE_0, STRUCT_0, EQREL_1, SUBSET_1,
      FINSEQ_1, LATTICE5, LATTICES, WAYBEL_0, ZFMISC_1, GROUP_6, FUNCT_1,
      RELAT_1, XXREAL_0, FINSET_1, ABIAN, CARD_1, ARYTM_3, CAT_1, YELLOW_0,
      ORDINAL2, ORDINAL1, TARSKI, WELLORD1, SEQM_3, LATTICE3, WAYBEL_1,
      MCART_1, VALUED_0, RELAT_2, PARTFUN1, FUNCOP_1, FUNCT_6, NAT_1, FUNCT_2,
      LATTICE8, RECDEF_2;
 notations TARSKI, XBOOLE_0, ZFMISC_1, XTUPLE_0, XFAMILY, SUBSET_1, RELAT_1,
      FUNCT_1, RELSET_1, FUNCT_2, FUNCT_6, ORDINAL1, NUMBERS, XCMPLX_0, NAT_1,
      ORDINAL2, MCART_1, DOMAIN_1, PARTFUN1, FUNCOP_1, STRUCT_0, ORDERS_2,
      EQREL_1, FINSEQ_1, LATTICE3, BINOP_1, YELLOW_0, YELLOW_2, LATTICE5,
      YELLOW11, WAYBEL_1, WAYBEL_0, ABIAN, XXREAL_0;
 constructors ORDINAL2, FUNCT_6, RFUNCT_3, ABIAN, REALSET2, ORDERS_3, WAYBEL_1,
      LATTICE5, YELLOW11, RELSET_1, XTUPLE_0, NUMBERS, XFAMILY;
 registrations XBOOLE_0, SUBSET_1, ORDINAL1, RELSET_1, PARTFUN1, FUNCOP_1,
      XREAL_0, INT_1, CARD_1, FINSEQ_1, EQREL_1, ABIAN, STRUCT_0, LATTICE3,
      YELLOW_0, YELLOW_2, WAYBEL_1, WAYBEL10, LATTICE5, YELLOW11, WAYBEL21,
      LATTICE7, ZFMISC_1, FUNCT_1, XTUPLE_0;
 requirements NUMERALS, REAL, BOOLE, SUBSET, ARITHM;
 definitions TARSKI, LATTICE3, FUNCOP_1, WAYBEL_0, YELLOW_0, YELLOW11,
      LATTICE5, XBOOLE_0, RELSET_1;
 equalities TARSKI, BINOP_1, YELLOW_2, ORDINAL1;
 expansions TARSKI, LATTICE3, WAYBEL_0, YELLOW11, LATTICE5, XBOOLE_0, BINOP_1,
      RELSET_1, ORDINAL1;
 theorems EQREL_1, RELAT_1, RELAT_2, FINSEQ_1, FINSEQ_2, ORDERS_2, TARSKI,
      ORDINAL1, ORDINAL3, TREES_2, PARTFUN1, GRFUNC_1, FUNCT_6, NAT_1,
      ZFMISC_1, FUNCT_1, FUNCT_2, LATTICE3, YELLOW_0, YELLOW_3, YELLOW_5,
      WAYBEL_0, WAYBEL_1, WAYBEL_6, RELSET_1, LATTICE5, YELLOW11, WAYBEL13,
      ORDERS_3, TEX_1, SYSREL, XBOOLE_0, XBOOLE_1, ORDERS_1, STRUCT_0,
      XTUPLE_0, XREGULAR;
 schemes RECDEF_1, ORDINAL2, NAT_1, FINSEQ_1, BINOP_1, CLASSES1;

begin :: Preliminaries

definition
  let L be RelStr;
  attr L is finitely_typed means
  :Def1:
  ex A being non empty set st
  (for e being object
    st e in the carrier of L holds e is Equivalence_Relation of A) & ex o
  being Element of NAT st
for e1,e2 being Equivalence_Relation of A, x,y being object
   st e1 in the carrier of L & e2 in the carrier of L & [x,y] in e1 "\/" e2
holds ex F being non empty FinSequence of A st len F = o & x,y are_joint_by F,
  e1,e2;
end;

definition
  let L be lower-bounded LATTICE;
  let n be Element of NAT;
  pred L has_a_representation_of_type<= n means

  ex A being non trivial
  set, f be Homomorphism of L,EqRelLATT A st f is one-to-one & Image f is
  finitely_typed & (ex e being Equivalence_Relation of A st e in the carrier of
  Image f & e <> id A) & type_of Image f <= n;
end;

registration
  cluster lower-bounded distributive finite for LATTICE;
  existence
  proof
    set L = the distributive finite LATTICE;
    take L;
    thus thesis;
  end;
end;

Lm1: 1 is odd
proof
  2*0+1 = 1;
  hence thesis;
end;

Lm2: 2 is even
proof
  2*1 = 2;
  hence thesis;
end;

registration
  let A be non trivial set;
  cluster non trivial finitely_typed full for
non empty Sublattice of EqRelLATT A;
  existence
  proof
    reconsider e1 = nabla A, e2 = id A as Element of EqRelLATT A by LATTICE5:4;
    set a = the Element of A;
    set b = the Element of A\{a};
    set Y = subrelstr {e1,e2};
A1: the carrier of Y = {e1,e2} by YELLOW_0:def 15;
    e1 = [:A,A:] by EQREL_1:def 1;
    then
A2: e2 <= e1 by LATTICE5:6;
A3: for x,y being Element of EqRelLATT A st x in the carrier of Y & y in
the carrier of Y & ex_inf_of {x,y},EqRelLATT A holds inf {x,y} in the carrier
    of Y
    proof
      let x,y be Element of EqRelLATT A;
      assume that
A4:   x in the carrier of Y & y in the carrier of Y and
      ex_inf_of {x,y},EqRelLATT A;
      per cases by A1,A4,TARSKI:def 2;
      suppose
        x = e1 & y = e1;
        then inf {x,y} = e1"/\"e1 by YELLOW_0:40
          .= e1 by YELLOW_5:2;
        hence thesis by A1,TARSKI:def 2;
      end;
      suppose
        x = e1 & y = e2;
        then inf {x,y} = e1"/\"e2 by YELLOW_0:40
          .= e2 by A2,YELLOW_5:10;
        hence thesis by A1,TARSKI:def 2;
      end;
      suppose
        x = e2 & y = e1;
        then inf {x,y} = e2"/\"e1 by YELLOW_0:40
          .= e2 by A2,YELLOW_5:10;
        hence thesis by A1,TARSKI:def 2;
      end;
      suppose
        x = e2 & y = e2;
        then inf {x,y} = e2"/\"e2 by YELLOW_0:40
          .= e2 by YELLOW_5:2;
        hence thesis by A1,TARSKI:def 2;
      end;
    end;
A5: Y is finitely_typed
    proof
      take A;
      thus for e being object st e in the carrier of Y holds e is
      Equivalence_Relation of A by A1,TARSKI:def 2;
      take o = 3;
      thus for eq1,eq2 being Equivalence_Relation of A,
      x1,y1 being object st eq1
in the carrier of Y & eq2 in the carrier of Y & [x1,y1] in eq1 "\/" eq2 holds
ex F being non empty FinSequence of A st len F = o & x1,y1 are_joint_by F,eq1,
      eq2
      proof
        let eq1,eq2 be Equivalence_Relation of A;
        let x1,y1 be object;
        assume that
A6:     eq1 in the carrier of Y and
A7:     eq2 in the carrier of Y and
A8:     [x1,y1] in eq1 "\/" eq2;
        eq1 = e2 or eq1 <> e2;
        then consider z being object such that
A9:     eq1 = e2 & z = x1 or eq1 <> e2 & z = y1;
        ex x2,y2 being object st [x1,y1] = [x2,y2] & x2 in A & y2 in A by A8,
RELSET_1:2;
        then x1 in A & y1 in A by XTUPLE_0:1;
        then reconsider F = <*x1,z,y1*> as non empty FinSequence of A by A9,
FINSEQ_2:14;
        take F;
        per cases by A9;
        suppose
A10:      eq1 = e2 & z = x1;
          then
A11:      F.2 = x1;
A13:      for i being Element of NAT st 1 <= i & i < len F holds (i is
odd implies [F.i,F.(i+1)] in eq1) & (i is even implies [F.i,F.(i+1)] in eq2)
          proof
            let i be Element of NAT;
            assume that
A14:        1 <= i and
A15:        i < len F;
            i < 2+1 by A15,FINSEQ_1:45;
            then i <= 2 by NAT_1:13;
            then
A16:        i = 0 or ... or i = 2 by NAT_1:60;
            per cases by A1,A7,A10,A14,A16,Lm1,Lm2,TARSKI:def 2;
            suppose
A17:          i = 1 & i is odd & eq1 = e2 & eq2 = e1;
              ex x2,y2 being object st [x1,y1] = [x2,y2] & x2 in A & y2 in A
              by A8,RELSET_1:2;
              then x1 in A by XTUPLE_0:1;
              hence thesis by A11,A17,EQREL_1:5;
            end;
            suppose
A18:          i = 1 & i is odd & eq1 = e2 & eq2 = e2;
              ex x2,y2 being object st [x1,y1] = [x2,y2] & x2 in A & y2 in A
              by A8,RELSET_1:2;
              then x1 in A by XTUPLE_0:1;
              hence thesis by A11,A18,EQREL_1:5;
            end;
            suppose
A19:          i = 2 & i is even & eq1 = e2 & eq2 = e1;
              then eq1 "\/" eq2 = e2 "\/" e1 by LATTICE5:10
                .= eq2 by A2,A19,YELLOW_5:8;
              hence thesis by A8,A11,A19;
            end;
            suppose
              i = 2 & i is even & eq1 = e2 & eq2 = e2;
              hence thesis by A8,A11;
            end;
          end;
          len F = 3 & F.3 = y1 by FINSEQ_1:45;
          hence thesis by A13;
        end;
        suppose
A20:      eq1 <> e2 & z = y1;
          then
A21:      F.2 = y1;
A23:      for i being Element of NAT st 1 <= i & i < len F holds (i is
odd implies [F.i,F.(i+1)] in eq1) & (i is even implies [F.i,F.(i+1)] in eq2)
          proof
            let i be Element of NAT;
            assume that
A24:        1 <= i and
A25:        i < len F;
            i < 2+1 by A25,FINSEQ_1:45;
            then i <= 2 by NAT_1:13;
            then
A26:        i = 0 or ... or i = 2 by NAT_1:60;
            per cases by A1,A6,A7,A20,A24,A26,Lm1,Lm2,TARSKI:def 2;
            suppose
              i = 1 & i is odd & eq1 = e1 & eq2 = e1;
              hence thesis by A8,A21;
            end;
            suppose
A27:          i = 1 & i is odd & eq1 = e1 & eq2 = e2;
              then eq1 "\/" eq2 = e1 "\/" e2 by LATTICE5:10
                .= eq1 by A2,A27,YELLOW_5:8;
              hence thesis by A8,A21,A27;
            end;
            suppose
A28:          i = 2 & i is even & eq1 = e1 & eq2 = e1;
              ex x2,y2 being object st [x1,y1] = [x2,y2] & x2 in A & y2 in A
              by A8,RELSET_1:2;
              then y1 in A by XTUPLE_0:1;
              hence thesis by A21,A28,EQREL_1:5;
            end;
            suppose
A29:          i = 2 & i is even & eq1 = e1 & eq2 = e2;
              ex x2,y2 being object st [x1,y1] = [x2,y2] & x2 in A & y2 in A
              by A8,RELSET_1:2;
              then y1 in A by XTUPLE_0:1;
              hence thesis by A21,A29,EQREL_1:5;
            end;
          end;
          len F = 3 & F.1 = x1 by FINSEQ_1:45;
          hence thesis by A23;
        end;
      end;
    end;
A30: for x,y being Element of EqRelLATT A st x in the carrier of Y & y in
the carrier of Y & ex_sup_of {x,y},EqRelLATT A holds sup {x,y} in the carrier
    of Y
    proof
      let x,y be Element of EqRelLATT A;
      assume that
A31:  x in the carrier of Y & y in the carrier of Y and
      ex_sup_of {x,y},EqRelLATT A;
      per cases by A1,A31,TARSKI:def 2;
      suppose
        x = e1 & y = e1;
        then sup {x,y} = e1"\/"e1 by YELLOW_0:41
          .= e1 by YELLOW_5:1;
        hence thesis by A1,TARSKI:def 2;
      end;
      suppose
        x = e1 & y = e2;
        then sup {x,y} = e1"\/"e2 by YELLOW_0:41
          .= e1 by A2,YELLOW_5:8;
        hence thesis by A1,TARSKI:def 2;
      end;
      suppose
        x = e2 & y = e1;
        then sup {x,y} = e2"\/"e1 by YELLOW_0:41
          .= e1 by A2,YELLOW_5:8;
        hence thesis by A1,TARSKI:def 2;
      end;
      suppose
        x = e2 & y = e2;
        then sup {x,y} = e2"\/"e2 by YELLOW_0:41
          .= e2 by YELLOW_5:1;
        hence thesis by A1,TARSKI:def 2;
      end;
    end;
A32: a <> b by ZFMISC_1:56;
A33: Y is non trivial
    proof
      assume Y is trivial;
      then ex s being Element of Y st the carrier of Y = {s} by TEX_1:def 1;
      then nabla A = id A by A1,ZFMISC_1:5;
      then [:A,A:] = id A by EQREL_1:def 1;
      then [a,b] in id A by ZFMISC_1:def 2;
      hence contradiction by A32,RELAT_1:def 10;
    end;
    reconsider Y as full non empty Sublattice of EqRelLATT A by A3,A30,
YELLOW_0:def 16,def 17;
    take Y;
    thus thesis by A33,A5;
  end;
end;

theorem Th1:
  for A be non empty set for L be lower-bounded LATTICE for d be
  distance_function of A,L holds succ {} c= DistEsti(d)
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be distance_function of A,L;
  succ {} c= DistEsti(d) or DistEsti(d) in succ {} by ORDINAL1:16;
  then succ {} c= DistEsti(d) or DistEsti(d) c= {} by ORDINAL1:22;
  hence thesis by LATTICE5:20,XBOOLE_1:3;
end;

theorem
  for L being trivial Semilattice holds L is modular
by STRUCT_0:def 10;

theorem
  for A being non empty set for L being non empty Sublattice of
EqRelLATT A holds L is trivial or ex e being Equivalence_Relation of A st e in
  the carrier of L & e <> id A
proof
  let A be non empty set;
  let L be non empty Sublattice of EqRelLATT A;
  now
    assume
A1: not ex e being Equivalence_Relation of A st e in the carrier of L
    & e <> id A;
    thus L is trivial
    proof
      consider x be object such that
A2:   x in the carrier of L by XBOOLE_0:def 1;
      the carrier of L c= the carrier of EqRelLATT A by YELLOW_0:def 13;
      then reconsider e=x as Equivalence_Relation of A by A2,LATTICE5:4;
      the carrier of L = {x}
      proof
        thus the carrier of L c= {x}
        proof
          let a be object;
          assume
A3:       a in the carrier of L;
          the carrier of L c= the carrier of EqRelLATT A by YELLOW_0:def 13;
          then reconsider B=a as Equivalence_Relation of A by A3,LATTICE5:4;
          B = id A by A1,A3
            .= e by A1,A2;
          hence thesis by TARSKI:def 1;
        end;
        let A be object;
        assume A in {x};
        hence thesis by A2,TARSKI:def 1;
      end;
      hence thesis;
    end;
  end;
  hence thesis;
end;

theorem
  for L1,L2 be lower-bounded LATTICE for f being Function of L1,L2
  st f is infs-preserving sups-preserving holds f is meet-preserving
  join-preserving;

theorem Th5:
  for L1,L2 be lower-bounded LATTICE st L1,L2 are_isomorphic & L1
  is modular holds L2 is modular
proof
  let L1,L2 be lower-bounded LATTICE;
  assume that
A1: L1,L2 are_isomorphic and
A2: L1 is modular;
  let a,b,c be Element of L2;
  consider f be Function of L1,L2 such that
A3: f is isomorphic by A1,WAYBEL_1:def 8;
  set C = f".c;
  set A = f".a;
  set B = f".b;
A4: f is one-to-one & rng f = the carrier of L2 by A3,WAYBEL_0:66;
  then
A5: b = f.B by FUNCT_1:35;
A6: C in dom f by A4,FUNCT_1:32;
A7: A in dom f & B in dom f by A4,FUNCT_1:32;
A8: a = f.A & c = f.C by A4,FUNCT_1:35;
  reconsider A,B,C as Element of L1 by A7,A6;
  assume a <= c;
  then A <= C by A3,A8,WAYBEL_0:66;
  then
A9: A"\/"(B"/\"C) = (A"\/"B)"/\"C by A2;
  f is infs-preserving sups-preserving by A3,WAYBEL13:20;
  then
A10: f is meet-preserving join-preserving;
  hence a"\/"(b"/\"c) = f.A "\/" f.(B"/\"C) by A5,A8,WAYBEL_6:1
    .= f.((A"\/"B)"/\"C) by A10,A9,WAYBEL_6:2
    .= (f.(A"\/"B)"/\"f.C) by A10,WAYBEL_6:1
    .= (a"\/"b)"/\"c by A10,A5,A8,WAYBEL_6:2;
end;

theorem Th6:
  for S being lower-bounded non empty Poset for T being non empty
  Poset for f being monotone Function of S,T holds Image f is lower-bounded
proof
  let S be lower-bounded non empty Poset;
  let T be non empty Poset;
  let f be monotone Function of S,T;
  thus Image f is lower-bounded
  proof
    consider x being Element of S such that
A1: x is_<=_than the carrier of S by YELLOW_0:def 4;
    dom f = the carrier of S by FUNCT_2:def 1;
    then f.x in rng f by FUNCT_1:def 3;
    then reconsider fx = f.x as Element of Image f by YELLOW_0:def 15;
    take fx;
    let b be Element of Image f;
    b in the carrier of subrelstr (rng f);
    then b in rng f by YELLOW_0:def 15;
    then consider c be object such that
A2: c in dom f and
A3: f.c = b by FUNCT_1:def 3;
A4: the carrier of Image f c= the carrier of T by YELLOW_0:def 13;
    assume b in the carrier of Image f;
    reconsider b1 = b as Element of T by A4;
    reconsider c as Element of S by A2;
    x <= c by A1;
    then f.x <= b1 by A3,ORDERS_3:def 5;
    hence fx <= b by YELLOW_0:60;
  end;
end;

theorem Th7:
  for L being lower-bounded LATTICE for x,y being Element of L for
A being non empty set for f be Homomorphism of L,EqRelLATT A st f is one-to-one
  holds (corestr f).x <= (corestr f).y implies x <= y
proof
  let L be lower-bounded LATTICE;
  let x,y be Element of L;
  let A be non empty set;
  let f be Homomorphism of L,EqRelLATT A;
  assume that
A1: f is one-to-one and
A2: (corestr f).x <= (corestr f).y;
  now
A3: corestr f = f by WAYBEL_1:30;
A4: for x,y being Element of L holds (corestr f).(x "/\" y) = (corestr f).
    x "/\" (corestr f).y
    proof
      let x,y be Element of L;
      thus (corestr f).(x "/\" y) = f.x "/\" f.y by A3,WAYBEL_6:1
        .= (corestr f).x "/\" (corestr f).y by A3,YELLOW_0:69;
    end;
A5: corestr f is one-to-one by A1,WAYBEL_1:30;
    (corestr f).y "/\" (corestr f).x = (corestr f).x by A2,YELLOW_5:10;
    then (corestr f).x = (corestr f).(x "/\" y) by A4;
    then
A6: x = x "/\" y by A5,WAYBEL_1:def 1;
    assume not x <= y;
    hence contradiction by A6,YELLOW_0:25;
  end;
  hence thesis;
end;

begin

theorem Th8:
  for A being non trivial set for L being finitely_typed full non
empty Sublattice of EqRelLATT A for e being Equivalence_Relation of A st e in
  the carrier of L & e <> id A holds type_of L <= 2 implies L is modular
proof
  let A be non trivial set;
  let L be finitely_typed full non empty Sublattice of EqRelLATT A;
  let e be Equivalence_Relation of A;
  assume that
A1: e in the carrier of L and
A2: e <> id A;
  assume
A3: type_of L <= 2;
  let a,b,c be Element of L;
A4: the carrier of L c= the carrier of EqRelLATT A by YELLOW_0:def 13;
  reconsider b9 = b as Equivalence_Relation of A by A4,LATTICE5:4;
  reconsider b99 = b9 as Element of EqRelLATT A by A4;
  reconsider a9 = a as Equivalence_Relation of A by A4,LATTICE5:4;
  reconsider c9 = c as Equivalence_Relation of A by A4,LATTICE5:4;
  reconsider c99 = c9 as Element of EqRelLATT A by A4;
  reconsider a99 = a9 as Element of EqRelLATT A by A4;
A5: (a99"\/"b99)"/\"c99 = (a99"\/"b99) /\ c9 by LATTICE5:8
    .= (a9"\/"b9) /\ c9 by LATTICE5:10;
  assume
A6: a <= c;
  then a99 <= c99 by YELLOW_0:59;
  then
A7: a9 c= c9 by LATTICE5:6;
A8: a99"\/"(b99"/\"c99) <= (a99"\/"b99)"/\"c99 by A6,YELLOW11:8,YELLOW_0:59;
A9: b9 /\ c9 = b99"/\"c99 by LATTICE5:8;
  then a9"\/"(b9 /\ c9) = a99"\/"(b99"/\"c99) by LATTICE5:10;
  then
A10: a9"\/"(b9 /\ c9) c= (a9"\/"b9) /\ c9 by A8,A5,LATTICE5:6;
  consider AA being non empty set such that
A11: for e being object st e in the carrier of L holds e is
  Equivalence_Relation of AA and
A12: ex i being Element of NAT st for e1,e2 being Equivalence_Relation
of AA, x,y being object
  st e1 in the carrier of L & e2 in the carrier of L & [x,y]
  in e1 "\/" e2 holds ex F being non empty FinSequence of AA st len F = i & x,y
  are_joint_by F,e1,e2 by Def1;
  e is Equivalence_Relation of AA by A1,A11;
  then
A13: field e = A & field e = AA by EQREL_1:9;
A14: (a9"\/"b9) /\ c9 c= a9"\/"(b9 /\ c9)
  proof
    let x,y be Element of A;
    assume
A15: [x,y] in (a9 "\/" b9) /\ c9;
    then
A16: [x,y] in a9 "\/" b9 by XBOOLE_0:def 4;
A17: [x,y] in c9 by A15,XBOOLE_0:def 4;
    type_of L = 0 or ... or type_of L = 2 by A3,NAT_1:60;
    then per cases;
    suppose
      type_of L = 2;
      then consider F being non empty FinSequence of A such that
A18:  len F = 2+2 and
A19:  x,y are_joint_by F,a9,b9 by A1,A2,A12,A13,A16,LATTICE5:def 4;
A20:  F.4 = y by A18,A19;
      consider l being Element of NAT such that
A21:  l = 1;
      2*l+1 = 3 by A21;
      then
A22:  [F.3,F.(3+1)] in a9 by A18,A19;
      consider k being Element of NAT such that
A23:  k = 1;
      2*k = 2 by A23;
      then
A24:  [F.2,F.(2+1)] in b9 by A18,A19;
A25:  F.1 = x by A19;
      reconsider BC = b9 /\ c9 as Element of EqRelLATT A by A9;
      set z1 = F.2;
      set z2 = F.3;
      consider j being Element of NAT such that
A26:  j = 0;
      2*j+1 = 1 by A26;
      then
A27:  [F.1,F.(1+1)] in a9 by A18,A19;
A28:  a9 "\/" (b9 /\ c9) = a99"\/" BC by LATTICE5:10;
      BC <= BC "\/" a99 by YELLOW_0:22;
      then
A29:  b9 /\ c9 c= a9 "\/" (b9 /\ c9) by A28,LATTICE5:6;
      a99 <= a99 "\/" BC by YELLOW_0:22;
      then
A30:  a9 c= a9 "\/" (b9 /\ c9) by A28,LATTICE5:6;
      [y,x] in c9 by A17,EQREL_1:6;
      then [z2,x] in c9 by A7,A20,A22,EQREL_1:7;
      then [z2,z1] in c9 by A7,A25,A27,EQREL_1:7;
      then [z1,z2] in c9 by EQREL_1:6;
      then [z1,z2] in b9 /\ c9 by A24,XBOOLE_0:def 4;
      then [x,z2] in a9 "\/" (b9 /\ c9) by A25,A27,A30,A29,EQREL_1:7;
      hence thesis by A20,A22,A30,EQREL_1:7;
    end;
    suppose
      type_of L = 1;
      then consider F being non empty FinSequence of A such that
A31:  len F = 1+2 and
A32:  x,y are_joint_by F,a9,b9 by A1,A2,A12,A13,A16,LATTICE5:def 4;
      set z1 = F.2;
      consider k being Element of NAT such that
A33:  k = 1;
      reconsider BC = b9 /\ c9 as Element of EqRelLATT A by A9;
      consider j being Element of NAT such that
A34:  j = 0;
      2*j+1 = 1 by A34;
      then
A35:  [F.1,F.(1+1)] in a9 by A31,A32;
      2*k = 2 by A33;
      then
A36:  [F.2,F.(2+1)] in b9 by A31,A32;
A37:  a9 "\/" (b9 /\ c9) = a99"\/" BC by LATTICE5:10;
A38:  [x,y] in c9 by A15,XBOOLE_0:def 4;
A39:  F.1 = x by A32;
      then [z1,x] in c9 by A7,A35,EQREL_1:6;
      then
A40:  [z1,y] in c9 by A38,EQREL_1:7;
      BC <= BC "\/" a99 by YELLOW_0:22;
      then
A41:  b9 /\ c9 c= a9 "\/" (b9 /\ c9) by A37,LATTICE5:6;
      a99 <= a99 "\/" BC by YELLOW_0:22;
      then
A42:  a9 c= a9 "\/" (b9 /\ c9) by A37,LATTICE5:6;
      F.3 = y by A31,A32;
      then [z1,y] in b9 /\ c9 by A36,A40,XBOOLE_0:def 4;
      hence thesis by A39,A35,A42,A41,EQREL_1:7;
    end;
    suppose
      type_of L = 0;
      then consider F being non empty FinSequence of A such that
A43:  len F = 0+2 & x,y are_joint_by F,a9,b9 by A1,A2,A12,A13,A16,
LATTICE5:def 4;
      reconsider BC = b9 /\ c9 as Element of EqRelLATT A by A9;
      consider j being Element of NAT such that
A44:  j = 0;
      2*j+1 = 1 by A44;
      then
A45:  [F.1,F.(1+1)] in a9 by A43;
      a99 <= a99 "\/" BC & a9 "\/" (b9 /\ c9) = a99"\/" BC by LATTICE5:10
,YELLOW_0:22;
      then
A46:  a9 c= a9 "\/" (b9 /\ c9) by LATTICE5:6;
      F.1 = x & F.2 = y by A43;
      hence thesis by A45,A46;
    end;
  end;
  a99"\/"b99 = a"\/"b by YELLOW_0:70;
  then
A47: (a"\/"b)"/\"c = (a99"\/"b99)"/\"c99 by YELLOW_0:69
    .= (a99"\/"b99) /\ c9 by LATTICE5:8
    .= (a9"\/"b9) /\ c9 by LATTICE5:10;
A48: b99"/\"c99 = b"/\"c by YELLOW_0:69;
  a9"\/"(b9 /\ c9) = a99"\/"(b99"/\"c99) by A9,LATTICE5:10
    .= a"\/"(b"/\"c) by A48,YELLOW_0:70;
  hence thesis by A10,A14,A47;
end;

theorem Th9:
  for L be lower-bounded LATTICE holds L
  has_a_representation_of_type<= 2 implies L is modular
proof
  let L be lower-bounded LATTICE;
  assume L has_a_representation_of_type<= 2;
  then consider
  A being non trivial set, f being Homomorphism of L,EqRelLATT A such
  that
A1: f is one-to-one and
A2: ( Image f is finitely_typed & ex e being Equivalence_Relation of A
  st e in the carrier of Image f & e <> id A )& type_of Image f <= 2;
A3: rng (corestr f) = the carrier of Image f & for x,y being Element of L
holds x <= y implies (corestr f).x <= (corestr f).y by FUNCT_2:def 3
,WAYBEL_1:def 2;
  corestr f is one-to-one & for x,y being Element of L holds (corestr f).x
  <= (corestr f).y implies x <= y by A1,Th7,WAYBEL_1:30;
  then corestr f is isomorphic by A3,WAYBEL_0:66;
  then
A4: L, Image f are_isomorphic by WAYBEL_1:def 8;
A5: Image f is lower-bounded LATTICE by Th6;
  Image f is modular by A2,Th8;
  hence thesis by A5,A4,Th5,WAYBEL_1:6;
end;

::  <=  ::   L is modular implies L has_a_representation_of_type<= 2

definition
  let A be set;
  func new_set2 A -> set equals
  A \/ {{A}, {{A}}};
  correctness;
end;

registration
  let A be set;
  cluster new_set2 A -> non empty;
  coherence;
end;

definition
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be Element of [:A,A,the carrier of L,the carrier of L:];
  func new_bi_fun2(d,q) -> BiFunction of new_set2 A,L means
  :Def4:
  (for u,v being Element of A holds it.(u,v) = d.(u,v)) &
   it.({A},{A}) = Bottom L & it.({{A}},{{A}}) = Bottom L &
   it.({A},{{A}}) = (d.(q`1_4,q`2_4)"\/"(q`3_4))"/\"(q`4_4) &
   it.({{A}
   },{A}) = (d.(q`1_4,q`2_4)"\/"(q`3_4))"/\"(q`4_4) &
  for u being Element of A
   holds it.(u,{A}) = d.(u,q`1_4)"\/"(q`3_4) &
    it.({A},u) = d.(u,q`1_4)"\/"(q`3_4) &
    it.(u,{{A}}) = d.(u,q`2_4) "\/"(q`3_4) &
    it.({{A}},u) = d.(u,q`2_4)"\/"(q`3_4);
  existence
  proof
    reconsider a = q`3_4, b = q`4_4 as Element of L;
    set x = q`1_4, y = q`2_4;
    defpred X[Element of new_set2 A,Element of new_set2 A,set] means ($1 in A
& $2 in A implies $3 = d.($1,$2)) & ($1 = {A} & $2 = {{A}} or $2 = {A} & $1 = {
{A}} implies $3 = (d.(x,y)"\/"a)"/\"b) & (($1 = {A} or $1 = {{A}}) & $2 = $1
implies $3 = Bottom L) & ($1 in A & $2 = {A} implies ex p9 being Element of A
st p9 = $1 & $3 = d.(p9,x)"\/"a) & ($1 in A & $2 = {{A}} implies ex p9 being
Element of A st p9 = $1 & $3 = d.(p9,y)"\/"a) & ($2 in A & $1 = {A} implies ex
q9 being Element of A st q9 = $2 & $3 = d.(q9,x)"\/"a) & ($2 in A & $1 = {{A}}
    implies ex q9 being Element of A st q9 = $2 & $3 = d.(q9,y)"\/"a);
    {{A}} in {{A}, {{A}} } by TARSKI:def 2;
    then
A1: {{A}} in new_set2 A by XBOOLE_0:def 3;
A2: for p,q being Element of new_set2 A ex r being Element of L st X[p,q,r ]
    proof
      let p,q be Element of new_set2 A;
A3:   p in A or p in {{A},{{A}}} by XBOOLE_0:def 3;
A4:   q in A or q in {{A},{{A}}} by XBOOLE_0:def 3;
A5:   (p = {A} or p = {{A}}) & p = q iff p = {A} & q = {A} or p = {{A}} &
      q = {{A}};
A6:   not {A} in A by TARSKI:def 1;
A7:   {A} <> {{A}}
      proof
        assume {A} = {{A}};
        then {A} in {A} by TARSKI:def 1;
        hence contradiction;
      end;
A8:   not {{A}} in A
      proof
A9:     A in {A} & {A} in {{A}} by TARSKI:def 1;
        assume {{A}} in A;
        hence contradiction by A9,XREGULAR:7;
      end;
      per cases by A3,A4,A5,TARSKI:def 2;
      suppose
        p in A & q in A;
        then reconsider p9=p,q9=q as Element of A;
        take d.(p9,q9);
        thus thesis by A6,A8;
      end;
      suppose
A10:    p = {A} & q = {{A}} or q = {A} & p = {{A}};
        take (d.(x,y)"\/"a)"/\"b;
        thus thesis by A7,A8,A10,TARSKI:def 1;
      end;
      suppose
A11:    (p = {A} or p = {{A}}) & q = p;
        take Bottom L;
        thus thesis by A7,A8,A11,TARSKI:def 1;
      end;
      suppose
A12:    p in A & q = {A};
        then reconsider p9 = p as Element of A;
        take d.(p9,x)"\/"a;
        thus thesis by A7,A8,A12,TARSKI:def 1;
      end;
      suppose
A13:    p in A & q = {{A}};
        then reconsider p9 = p as Element of A;
        take d.(p9,y)"\/"a;
        thus thesis by A7,A8,A13,TARSKI:def 1;
      end;
      suppose
A14:    q in A & p = {A};
        then reconsider q9 = q as Element of A;
        take d.(q9,x)"\/"a;
        thus thesis by A7,A8,A14,TARSKI:def 1;
      end;
      suppose
A15:    q in A & p = {{A}};
        then reconsider q9 = q as Element of A;
        take d.(q9,y)"\/"a;
        thus thesis by A7,A8,A15,TARSKI:def 1;
      end;
    end;
    consider f being Function of [:new_set2 A,new_set2 A:],the carrier of L
    such that
A16: for p,q being Element of new_set2 A holds X[p,q,f.(p,q)] from
    BINOP_1:sch 3(A2);
    reconsider f as BiFunction of new_set2 A,L;
    {A} in {{A}, {{A}} } by TARSKI:def 2;
    then
A17: {A} in new_set2 A by XBOOLE_0:def 3;
A18: for u being Element of A holds f.({A},u) = d.(u,x)"\/"a & f.({{A}},u)
    = d.(u,y)"\/"a
    proof
      let u be Element of A;
      reconsider u9 = u as Element of new_set2 A by XBOOLE_0:def 3;
      ex u1 being Element of A st u1 = u9 & f.({A},u9) = d.(u1, x)"\/"a by A17
,A16;
      hence f.({A},u) = d.(u,x)"\/"a;
      ex u2 being Element of A st u2 = u9 & f.({{A}},u9) = d.( u2,y)"\/"a
      by A1,A16;
      hence thesis;
    end;
    take f;
A19: for u,v being Element of A holds f.(u,v) = d.(u,v)
    proof
      let u,v be Element of A;
      reconsider u9 = u, v9 = v as Element of new_set2 A by XBOOLE_0:def 3;
      thus f.(u,v) = f.(u9,v9) .= d.(u,v) by A16;
    end;
    for u being Element of A holds f.(u,{A}) = d.(u,x)"\/"a & f.(u,{{A}})
    = d.(u,y)"\/"a
    proof
      let u be Element of A;
      reconsider u9 = u as Element of new_set2 A by XBOOLE_0:def 3;
      ex u1 being Element of A st u1 = u9 & f.(u9,{A}) = d.(u1, x)"\/"a by A17
,A16;
      hence f.(u,{A}) = d.(u,x)"\/"a;
      ex u2 being Element of A st u2 = u9 & f.(u9,{{A}}) = d.( u2,y)"\/"a
      by A1,A16;
      hence thesis;
    end;
    hence thesis by A17,A1,A16,A19,A18;
  end;
  uniqueness
  proof
    set x = q`1_4, y = q`2_4, a = q`3_4;
    let f1,f2 be BiFunction of new_set2 A,L such that
A20: for u,v being Element of A holds f1.(u,v) = d.(u,v) and
A21: f1.({A},{A}) = Bottom L and
A22: f1.({{A}},{{A}}) = Bottom L and
A23: f1.({A},{{A}}) = (d.(q`1_4,q`2_4)"\/"(q`3_4))"/\"(q`4_4) and
A24: f1.({{A}},{A}) = (d.(q`1_4,q`2_4)"\/"(q`3_4))"/\"(q`4_4) and
A25: for u being Element of A
    holds
      f1.(u,{A}) = d.(u,q`1_4)"\/"(q`3_4) &
      f1.( {A},u) = d.(u,q`1_4)"\/"(q`3_4) &
      f1.(u,{{A}}) = d.(u,q`2_4)"\/"(q`3_4) &
      f1.({{A}},u) = d. (u,q`2_4)"\/"(q`3_4) and
A26: for u,v being Element of A holds f2.(u,v) = d.(u,v) and
A27: f2.({A},{A}) = Bottom L and
A28: f2.({{A}},{{A}}) = Bottom L and
A29: f2.({A},{{A}}) = (d.(q`1_4,q`2_4)"\/"(q`3_4))"/\"(q`4_4) and
A30: f2.({{A}},{A}) = (d.(q`1_4,q`2_4)"\/"(q`3_4))"/\"(q`4_4) and
A31: for u being Element of A holds
      f2.(u,{A}) = d.(u,q`1_4)"\/"(q`3_4) &
      f2.({A},u) = d.(u,q`1_4)"\/"(q`3_4) &
      f2.(u,{{A}}) = d.(u,q`2_4)"\/"(q`3_4) &
      f2.({{A}},u) = d. (u,q`2_4)"\/"(q`3_4);
    now
      let p,q be Element of new_set2 A;
A32:  p in A or p in {{A},{{A}}} by XBOOLE_0:def 3;
A33:  q in A or q in {{A},{{A}}} by XBOOLE_0:def 3;
      per cases by A32,A33,TARSKI:def 2;
      suppose
A34:    p in A & q in A;
        hence f1.(p,q) = d.(p,q) by A20
          .= f2.(p,q) by A26,A34;
      end;
      suppose
A35:    p in A & q = {A};
        then reconsider p9 = p as Element of A;
        thus f1.(p,q) = d.(p9,x)"\/"a by A25,A35
          .= f2.(p,q) by A31,A35;
      end;
      suppose
A36:    p in A & q = {{A}};
        then reconsider p9 = p as Element of A;
        thus f1.(p,q) = d.(p9,y)"\/"a by A25,A36
          .= f2.(p,q) by A31,A36;
      end;
      suppose
A37:    p = {A} & q in A;
        then reconsider q9 = q as Element of A;
        thus f1.(p,q) = d.(q9,x)"\/"a by A25,A37
          .= f2.(p,q) by A31,A37;
      end;
      suppose
        p = {A} & q = {A};
        hence f1.(p,q) = f2.(p,q) by A21,A27;
      end;
      suppose
        p = {A} & q = {{A}};
        hence f1.(p,q) = f2.(p,q) by A23,A29;
      end;
      suppose
A38:    p = {{A}} & q in A;
        then reconsider q9 = q as Element of A;
        thus f1.(p,q) = d.(q9,y)"\/"a by A25,A38
          .= f2.(p,q) by A31,A38;
      end;
      suppose
        p = {{A}} & q = {A};
        hence f1.(p,q) = f2.(p,q) by A24,A30;
      end;
      suppose
        p = {{A}} & q = {{A}};
        hence f1.(p,q) = f2.(p,q) by A22,A28;
      end;
    end;
    hence f1 = f2;
  end;
end;

theorem Th10:
  for A being non empty set for L being lower-bounded LATTICE for
  d being BiFunction of A,L st d is zeroed for q being Element of [:A,A,the
  carrier of L,the carrier of L:] holds new_bi_fun2(d,q) is zeroed
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  assume
A1: d is zeroed;
  let q be Element of [:A,A,the carrier of L,the carrier of L:];
  set f = new_bi_fun2(d,q);
  for u being Element of new_set2 A holds f.(u,u) = Bottom L
  proof
    let u be Element of new_set2 A;
A2: u in A or u in {{A},{{A}}} by XBOOLE_0:def 3;
    per cases by A2,TARSKI:def 2;
    suppose
      u in A;
      then reconsider u9 = u as Element of A;
      thus f.(u,u) = d.(u9,u9) by Def4
        .= Bottom L by A1;
    end;
    suppose
      u = {A} or u = {{A}};
      hence thesis by Def4;
    end;
  end;
  hence thesis;
end;

theorem Th11:
  for A being non empty set for L being lower-bounded LATTICE for
  d being BiFunction of A,L st d is symmetric for q being Element of [:A,A,the
  carrier of L,the carrier of L:] holds new_bi_fun2(d,q) is symmetric
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  assume
A1: d is symmetric;
  let q be Element of [:A,A,the carrier of L,the carrier of L:];
  set f = new_bi_fun2(d,q), x = q`1_4, y = q`2_4, a = q`3_4, b = q`4_4;
  let p,q be Element of new_set2 A;
A2: p in A or p in {{A},{{A}}} by XBOOLE_0:def 3;
A3: q in A or q in {{A},{{A}}} by XBOOLE_0:def 3;
  per cases by A2,A3,TARSKI:def 2;
  suppose
    p in A & q in A;
    then reconsider p9 = p, q9 = q as Element of A;
    thus f.(p,q) = d.(p9,q9) by Def4
      .= d.(q9,p9) by A1
      .= f.(q,p) by Def4;
  end;
  suppose
A4: p in A & q = {A};
    then reconsider p9 = p as Element of A;
    thus f.(p,q) = d.(p9,x)"\/"a by A4,Def4
      .= f.(q,p) by A4,Def4;
  end;
  suppose
A5: p in A & q = {{A}};
    then reconsider p9 = p as Element of A;
    thus f.(p,q) = d.(p9,y)"\/"a by A5,Def4
      .= f.(q,p) by A5,Def4;
  end;
  suppose
A6: p = {A} & q in A;
    then reconsider q9 = q as Element of A;
    thus f.(p,q) = d.(q9,x)"\/"a by A6,Def4
      .= f.(q,p) by A6,Def4;
  end;
  suppose
    p = {A} & q = {A};
    hence thesis;
  end;
  suppose
A7: p = {A} & q = {{A}};
    hence f.(p,q) = (d.(x,y)"\/"a)"/\"b by Def4
      .= f.(q,p) by A7,Def4;
  end;
  suppose
A8: p = {{A}} & q in A;
    then reconsider q9 = q as Element of A;
    thus f.(p,q) = d.(q9,y)"\/"a by A8,Def4
      .= f.(q,p) by A8,Def4;
  end;
  suppose
A9: p = {{A}} & q = {A};
    hence f.(p,q) = (d.(x,y)"\/"a)"/\"b by Def4
      .= f.(q,p) by A9,Def4;
  end;
  suppose
    p = {{A}} & q = {{A}};
    hence thesis;
  end;
end;

theorem Th12:
  for A being non empty set for L being lower-bounded LATTICE st L
is modular for d being BiFunction of A,L st d is symmetric & d is u.t.i. for q
being Element of [:A,A,the carrier of L,the carrier of L:]
  st d.(q`1_4,q`2_4) <= (q`3_4)"\/"(q`4_4) holds new_bi_fun2(d,q) is u.t.i.
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  assume
A1: L is modular;
  reconsider B = {{A}, {{A}}} as non empty set;
  let d be BiFunction of A,L;
  assume that
A2: d is symmetric and
A3: d is u.t.i.;
  let q be Element of [:A,A,the carrier of L,the carrier of L:];
  set x = q`1_4, y = q`2_4, a = q`3_4, b = q`4_4, f = new_bi_fun2(d,q);
  reconsider a,b as Element of L;
A4: for p,q,u being Element of new_set2 A st p in A & q in A & u in B holds
  f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume
A5: p in A & q in A & u in B;
    per cases by A5,TARSKI:def 2;
    suppose
A6:   p in A & q in A & u = {A};
      then reconsider p9 = p, q9 = q as Element of A;
A7:   f.(p,q) = d.(p9,q9) by Def4;
      d.(p9,x) <= d.(p9,q9) "\/" d.(q9,x) by A3;
      then
A8:   d.(p9,x)"\/"a <= (d.(p9,q9) "\/" d.(q9,x))"\/"a by WAYBEL_1:2;
      f.(p,u) = d.(p9,x)"\/"a & f.(q,u) = d.(q9,x)"\/"a by A6,Def4;
      hence thesis by A7,A8,LATTICE3:14;
    end;
    suppose
A9:   p in A & q in A & u = {{A}};
      then reconsider p9 = p, q9 = q as Element of A;
A10:  f.(p,q) = d.(p9,q9) by Def4;
      d.(p9,y) <= d.(p9,q9) "\/" d.(q9,y) by A3;
      then
A11:  d.(p9,y)"\/"a <= (d.(p9,q9) "\/" d.(q9,y))"\/"a by WAYBEL_1:2;
      f.(p,u) = d.(p9,y)"\/"a & f.(q,u) = d.(q9,y)"\/"a by A9,Def4;
      hence thesis by A10,A11,LATTICE3:14;
    end;
  end;
  assume
A12: d.(q`1_4,q`2_4) <= (q`3_4)"\/"(q`4_4);
A13: for p,q,u being Element of new_set2 A st p in A & q in B & u in B holds
  f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume
A14: p in A & q in B & u in B;
    per cases by A14,TARSKI:def 2;
    suppose
A15:  p in A & q = {A} & u = {A};
      then f.(p,q) "\/" f.(q,u) = Bottom L"\/"f.(p,q) by Def4
        .= f.(p,q) by WAYBEL_1:3;
      hence thesis by A15;
    end;
    suppose
A16:  p in A & q = {A} & u = {{A}};
      then reconsider p9 = p as Element of A;
      a <= a "\/" d.(x,y) by YELLOW_0:22;
      then
A17:  a"\/"((d.(x,y)"\/"a)"/\"b) = (a"\/"b)"/\"(a"\/" d.(x,y)) by A1;
      d.(p9,y) <= d.(p9,x)"\/"d.(x,y) by A3;
      then
A18:  d.(p9,y)"\/"a <= (d.(p9,x)"\/"d.(x,y))"\/"a by YELLOW_5:7;
      a <= a;
      then d.(x,y)"\/"a <= (a"\/"b)"\/"a by A12,YELLOW_3:3;
      then
      (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) <= (d.(x,y)"\/"a)"/\"((a"\/"b)"\/"
      a) by YELLOW_5:6;
      then
A19:  d.(x,y)"\/"a = (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) & d.(p9,x)"\/"((d.(
x,y)"\/"a )"/\"(d.(x,y)"\/"a)) <= d.(p9,x)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/"
      a)) by WAYBEL_1:2,YELLOW_5:2;
      f.(p,q) = d.(p9,x)"\/"a & f.(q,u) = (d.(x,y)"\/"a)"/\"b by A16,Def4;
      then
      f.(p,q) "\/" f.(q,u) = d.(p9,x)"\/"((a"\/"b)"/\"(a"\/" d.(x,y))) by A17,
LATTICE3:14
        .= d.(p9,x)"\/"((d.(x,y)"\/"a)"/\"((a"\/"a)"\/"b)) by YELLOW_5:1
        .= d.(p9,x)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/" a)) by LATTICE3:14;
      then (d.(p9,x)"\/"d.(x,y))"\/"a <= f.(p,q) "\/" f.(q,u) by A19,
LATTICE3:14;
      then d.(p9,y)"\/"a <= f.(p,q) "\/" f.(q,u) by A18,ORDERS_2:3;
      hence thesis by A16,Def4;
    end;
    suppose
A20:  p in A & q = {{A}} & u = {A};
      then reconsider p9 = p as Element of A;
      a <= a "\/" d.(x,y) by YELLOW_0:22;
      then
A21:  a"\/"((d.(x,y)"\/"a)"/\"b) = (a"\/"b)"/\"(a"\/" d.(x,y)) by A1;
      a <= a;
      then d.(x,y)"\/"a <= (a"\/"b)"\/"a by A12,YELLOW_3:3;
      then
      (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) <= (d.(x,y)"\/"a)"/\"((a"\/"b)"\/"
      a) by YELLOW_5:6;
      then
A22:  d.(x,y)"\/"a = (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) & d.(p9,y)"\/"((d.(
x,y)"\/"a )"/\"(d.(x,y)"\/"a)) <= d.(p9,y)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/"
      a)) by WAYBEL_1:2,YELLOW_5:2;
      d.(y,x) = d.(x,y) by A2;
      then d.(p9,x) <= d.(p9,y)"\/"d.(x,y) by A3;
      then
A23:  d.(p9,x)"\/"a <= (d.(p9,y)"\/"d.(x,y))"\/"a by YELLOW_5:7;
      f.(p,q) = d.(p9,y)"\/"a & f.(q,u) = (d.(x,y)"\/"a)"/\"b by A20,Def4;
      then
      f.(p,q) "\/" f.(q,u) = d.(p9,y)"\/"((a"\/"b)"/\"(a"\/" d.(x,y))) by A21,
LATTICE3:14
        .= d.(p9,y)"\/"((d.(x,y)"\/"a)"/\"((a"\/"a)"\/"b)) by YELLOW_5:1
        .= d.(p9,y)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/" a)) by LATTICE3:14;
      then (d.(p9,y)"\/"d.(x,y))"\/"a <= f.(p,q) "\/" f.(q,u) by A22,
LATTICE3:14;
      then d.(p9,x)"\/"a <= f.(p,q) "\/" f.(q,u) by A23,ORDERS_2:3;
      hence thesis by A20,Def4;
    end;
    suppose
A24:  p in A & q = {{A}} & u = {{A}};
      then f.(p,q) "\/" f.(q,u) = Bottom L"\/"f.(p,q) by Def4
        .= f.(p,q) by WAYBEL_1:3;
      hence thesis by A24;
    end;
  end;
A25: for p,q,u being Element of new_set2 A st p in B & q in A & u in B holds
  f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume
A26: p in B & q in A & u in B;
    per cases by A26,TARSKI:def 2;
    suppose
      q in A & p = {A} & u = {A};
      then f.(p,u) = Bottom L by Def4;
      hence thesis by YELLOW_0:44;
    end;
    suppose
A27:  q in A & p = {A} & u = {{A}};
      then reconsider q9 = q as Element of A;
      d.(q9,x) = d.(x,q9) by A2;
      then
A28:  d.(x,y) <= d.(q9,x)"\/"d.(q9,y) by A3;
      f.(p,q) = d.(q9,x)"\/"a by A27,Def4;
      then f.(p,q) "\/" f.(q,u) = d.(q9,x)"\/"a"\/"(d.(q9,y)"\/"a) by A27,Def4
        .= d.(q9,x)"\/"(d.(q9,y)"\/"a)"\/"a by LATTICE3:14
        .= d.(q9,x)"\/"d.(q9,y)"\/"a"\/"a by LATTICE3:14
        .= d.(q9,x)"\/"d.(q9,y)"\/"(a"\/"a) by LATTICE3:14
        .= d.(q9,x)"\/"d.(q9,y)"\/"a by YELLOW_5:1;
      then
A29:  d.(x,y)"\/"a <= f.(p,q) "\/" f.(q,u) by A28,YELLOW_5:7;
A30:  (d.(x,y)"\/"a)"/\"b <= d.(x,y)"\/"a by YELLOW_0:23;
      f.(p,u) = (d.(x,y)"\/"a)"/\"b by A27,Def4;
      hence thesis by A29,A30,ORDERS_2:3;
    end;
    suppose
A31:  q in A & p = {{A}} & u = {A};
      then reconsider q9 = q as Element of A;
      d.(q9,x) = d.(x,q9) by A2;
      then
A32:  d.(x,y) <= d.(q9,x)"\/"d.(q9,y) by A3;
      f.(p,q) = d.(q9,y)"\/"a by A31,Def4;
      then
      f.(p,q) "\/" f.(q,u) = d.(q9,x)"\/"a"\/"(d.(q9,y)"\/"a) by A31,Def4
        .= d.(q9,x)"\/"(d.(q9,y)"\/"a)"\/"a by LATTICE3:14
        .= d.(q9,x)"\/"d.(q9,y)"\/"a"\/"a by LATTICE3:14
        .= d.(q9,x)"\/"d.(q9,y)"\/"(a"\/"a) by LATTICE3:14
        .= d.(q9,x)"\/"d.(q9,y)"\/"a by YELLOW_5:1;
      then
A33:  d.(x,y)"\/"a <= f.(p,q) "\/" f.(q,u) by A32,YELLOW_5:7;
A34:  (d.(x,y)"\/"a)"/\"b <= d.(x,y)"\/"a by YELLOW_0:23;
      f.(p,u) = (d.(x,y)"\/"a)"/\"b by A31,Def4;
      hence thesis by A33,A34,ORDERS_2:3;
    end;
    suppose
      q in A & p = {{A}} & u = {{A}};
      then f.(p,u) = Bottom L by Def4;
      hence thesis by YELLOW_0:44;
    end;
  end;
A35: for p,q,u being Element of new_set2 A st p in B & q in B & u in B
  holds f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume
A36: p in B & q in B & u in B;
    per cases by A36,TARSKI:def 2;
    suppose
A37:  p = {A} & q = {A} & u = {A};
      Bottom L <= f.(p,q) "\/" f.(q,u) by YELLOW_0:44;
      hence thesis by A37,Def4;
    end;
    suppose
A38:  p = {A} & q = {A} & u = {{A}};
      then f.(p,q) "\/" f.(q,u) = Bottom L "\/" f.(p,u) by Def4
        .= Bottom L "\/" ((d.(x,y)"\/"a)"/\"b) by A38,Def4
        .= ((d.(x,y)"\/"a)"/\"b) by WAYBEL_1:3;
      hence thesis by A38,Def4;
    end;
    suppose
A39:  p = {A} & q = {{A}} & u = {A};
      Bottom L <= f.(p,q) "\/" f.(q,u) by YELLOW_0:44;
      hence thesis by A39,Def4;
    end;
    suppose
A40:  p = {A} & q = {{A}} & u = {{A}};
      then f.(p,q) "\/" f.(q,u) = ((d.(x,y)"\/"a)"/\"b)"\/"f.(q,u) by Def4
        .= Bottom L"\/"((d.(x,y)"\/"a)"/\"b) by A40,Def4
        .= ((d.(x,y)"\/"a)"/\"b) by WAYBEL_1:3;
      hence thesis by A40,Def4;
    end;
    suppose
A41:  p = {{A}} & q = {A} & u = {A};
      then f.(p,q) "\/" f.(q,u) = ((d.(x,y)"\/"a)"/\"b)"\/" f.(q,u) by Def4
        .= Bottom L"\/"((d.(x,y)"\/"a)"/\"b) by A41,Def4
        .= ((d.(x,y)"\/"a)"/\"b) by WAYBEL_1:3
        .= f.(p,q) by A41,Def4;
      hence thesis by A41;
    end;
    suppose
A42:  p = {{A}} & q = {A} & u = {{A}};
      Bottom L <= f.(p,q) "\/" f.(q,u) by YELLOW_0:44;
      hence thesis by A42,Def4;
    end;
    suppose
A43:  p = {{A}} & q = {{A}} & u = {A};
      then f.(p,q) "\/" f.(q,u) = Bottom L"\/" f.(p,u) by Def4
        .= Bottom L"\/"((d.(x,y)"\/"a)"/\"b) by A43,Def4
        .= ((d.(x,y)"\/"a)"/\"b) by WAYBEL_1:3;
      hence thesis by A43,Def4;
    end;
    suppose
A44:  p = {{A}} & q = {{A}} & u = {{A}};
      Bottom L <= f.(p,q) "\/" f.(q,u) by YELLOW_0:44;
      hence thesis by A44,Def4;
    end;
  end;
A45: for p,q,u being Element of new_set2 A st p in B & q in B & u in A
  holds f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume
A46: p in B & q in B & u in A;
    per cases by A46,TARSKI:def 2;
    suppose
A47:  u in A & q = {A} & p = {A};
      then f.(p,q)"\/"f.(q,u) = Bottom L"\/"f.(q,u) by Def4
        .= f.(p,u) by A47,WAYBEL_1:3;
      hence thesis;
    end;
    suppose
A48:  u in A & q = {A} & p = {{A}};
      then reconsider u9 = u as Element of A;
      a <= a "\/" d.(x,y) by YELLOW_0:22;
      then
A49:  a"\/"((d.(x,y)"\/"a)"/\"b) = (a"\/"b)"/\"(a"\/" d.(x,y)) by A1;
      d.(u9,y) <= d.(u9,x)"\/"d.(x,y) by A3;
      then
A50:  d.(u9,y)"\/"a <= (d.(u9,x)"\/"d.(x,y))"\/"a by YELLOW_5:7;
      a <= a;
      then d.(x,y)"\/"a <= (a"\/"b)"\/"a by A12,YELLOW_3:3;
      then (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) <= (d.(x,y)"\/"a)"/\"((a"\/"b)
      "\/"a) by YELLOW_5:6;
      then
A51:  d.(x,y)"\/"a = (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) & d.(u9,x)"\/"((d.
(x,y)"\/"a )"/\"(d.(x,y)"\/"a)) <= d.(u9,x)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/"
      a)) by WAYBEL_1:2,YELLOW_5:2;
      f.(p,q) = (d.(x,y)"\/"a)"/\"b & f.(q,u) = d.(u9,x)"\/"a by A48,Def4;
      then f.(p,q) "\/" f.(q,u) = d.(u9,x)"\/"((a"\/"b)"/\"(a"\/" d.(x,y)))
      by A49,LATTICE3:14
        .= d.(u9,x)"\/"((d.(x,y)"\/"a)"/\"((a"\/"a)"\/"b)) by YELLOW_5:1
        .= d.(u9,x)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/" a)) by LATTICE3:14;
      then (d.(u9,x)"\/"d.(x,y))"\/"a <= f.(p,q) "\/" f.(q,u) by A51,
LATTICE3:14;
      then d.(u9,y)"\/"a <= f.(p,q) "\/" f.(q,u) by A50,ORDERS_2:3;
      hence thesis by A48,Def4;
    end;
    suppose
A52:  u in A & q = {{A}} & p = {A};
      then reconsider u9 = u as Element of A;
      a <= a "\/" d.(x,y) by YELLOW_0:22;
      then
A53:  a"\/"((d.(x,y)"\/"a)"/\"b) = (a"\/"b)"/\"(a"\/" d.(x,y)) by A1;
      a <= a;
      then d.(x,y)"\/"a <= (a"\/"b)"\/"a by A12,YELLOW_3:3;
      then (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) <= (d.(x,y)"\/"a)"/\"((a"\/"b)
      "\/"a) by YELLOW_5:6;
      then
A54:  d.(x,y)"\/"a = (d.(x,y)"\/"a)"/\"(d.(x,y)"\/"a) & d.(u9,y)"\/"((d.
(x,y)"\/"a )"/\"(d.(x,y)"\/"a)) <= d.(u9,y)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/"
      a)) by WAYBEL_1:2,YELLOW_5:2;
      d.(y,x) = d.(x,y) by A2;
      then d.(u9,x) <= d.(u9,y)"\/"d.(x,y) by A3;
      then
A55:  d.(u9,x)"\/"a <= (d.(u9,y)"\/"d.(x,y))"\/"a by YELLOW_5:7;
      f.(p,q) = (d.(x,y)"\/"a)"/\"b & f.(q,u) = d.(u9,y)"\/"a by A52,Def4;
      then f.(p,q) "\/" f.(q,u) = d.(u9,y)"\/"((a"\/"b)"/\"(a"\/" d.(x,y)))
      by A53,LATTICE3:14
        .= d.(u9,y)"\/"((d.(x,y)"\/"a)"/\"((a"\/"a)"\/"b)) by YELLOW_5:1
        .= d.(u9,y)"\/"((d.(x,y)"\/"a)"/\"((a"\/"b)"\/" a)) by LATTICE3:14;
      then (d.(u9,y)"\/"d.(x,y))"\/"a <= f.(p,q) "\/" f.(q,u) by A54,
LATTICE3:14;
      then d.(u9,x)"\/"a <= f.(p,q) "\/" f.(q,u) by A55,ORDERS_2:3;
      hence thesis by A52,Def4;
    end;
    suppose
A56:  u in A & q = {{A}} & p = {{A}};
      then f.(p,q)"\/"f.(q,u) = Bottom L"\/"f.(q,u) by Def4
        .= f.(p,u) by A56,WAYBEL_1:3;
      hence thesis;
    end;
  end;
A57: for p,q,u being Element of new_set2 A st p in B & q in A & u in A holds
  f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume that
A58: p in B and
A59: q in A & u in A;
    reconsider q9 = q, u9 = u as Element of A by A59;
    per cases by A58,A59,TARSKI:def 2;
    suppose
A60:  p = {A} & q in A & u in A;
      d.(u9,x) <= d.(u9,q9) "\/" d.(q9,x) by A3;
      then d.(u9,x) <= d.(q9,u9) "\/" d.(q9,x) by A2;
      then d.(u9,x)"\/"a <= (d.(q9,x)"\/"d.(q9,u9))"\/"a by WAYBEL_1:2;
      then
A61:  d.(u9,x)"\/"a <= (d.(q9,x)"\/"a)"\/"d.(q9,u9) by LATTICE3:14;
A62:  f.(q,u) = d.(q9,u9) by Def4;
      f.(p,q) = d.(q9,x)"\/"a by A60,Def4;
      hence thesis by A60,A62,A61,Def4;
    end;
    suppose
A63:  p = {{A}} & q in A & u in A;
      d.(u9,y) <= d.(u9,q9) "\/" d.(q9,y) by A3;
      then d.(u9,y) <= d.(q9,u9) "\/" d.(q9,y) by A2;
      then d.(u9,y)"\/"a <= (d.(q9,y)"\/"d.(q9,u9))"\/"a by WAYBEL_1:2;
      then
A64:  d.(u9,y)"\/"a <= (d.(q9,y)"\/"a)"\/"d.(q9,u9) by LATTICE3:14;
A65:  f.(q,u) = d.(q9,u9) by Def4;
      f.(p,q) = d.(q9,y)"\/"a by A63,Def4;
      hence thesis by A63,A65,A64,Def4;
    end;
  end;
A66: for p,q,u being Element of new_set2 A st p in A & q in B & u in A holds
  f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume
A67: p in A & q in B & u in A;
    per cases by A67,TARSKI:def 2;
    suppose
A68:  p in A & u in A & q = {A};
      then reconsider p9 = p, u9 = u as Element of A;
      d.(p9,u9) <= d.(p9,x) "\/" d.(x,u9) by A3;
      then
A69:  d.(p9,x) "\/" d.(u9,x) <= (d.(p9,x) "\/" d.(u9,x))"\/"a & d.(p9,u9)
      <= d.(p9,x) "\/" d.(u9,x) by A2,YELLOW_0:22;
      (d.(p9,x)"\/"d.(u9,x))"\/"a = d.(p9,x)"\/"(d.(u9,x)"\/"a) by LATTICE3:14
        .= d.(p9,x)"\/"(d.(u9,x)"\/"(a"\/"a)) by YELLOW_5:1
        .= d.(p9,x)"\/"((d.(u9,x)"\/"a)"\/"a) by LATTICE3:14
        .= (d.(p9,x)"\/"a) "\/" (d.(u9,x)"\/"a) by LATTICE3:14;
      then
A70:  d.(p9,u9) <= (d.(p9,x)"\/"a) "\/" (d.(u9,x)"\/"a) by A69,ORDERS_2:3;
      f.(p,q) = d.(p9,x)"\/"a & f.(q,u) = d.(u9,x)"\/"a by A68,Def4;
      hence thesis by A70,Def4;
    end;
    suppose
A71:  p in A & u in A & q = {{A}};
      then reconsider p9 = p, u9 = u as Element of A;
      d.(p9,u9) <= d.(p9,y) "\/" d.(y,u9) by A3;
      then
A72:  d.(p9,y) "\/" d.(u9,y) <= (d.(p9,y) "\/" d.(u9,y))"\/"a & d.(p9,u9)
      <= d.(p9,y) "\/" d.(u9,y) by A2,YELLOW_0:22;
      (d.(p9,y)"\/"d.(u9,y))"\/"a = d.(p9,y)"\/"(d.(u9,y)"\/"a) by LATTICE3:14
        .= d.(p9,y)"\/"(d.(u9,y)"\/"(a"\/"a)) by YELLOW_5:1
        .= d.(p9,y)"\/"((d.(u9,y)"\/"a)"\/"a) by LATTICE3:14
        .= (d.(p9,y)"\/"a)"\/"(d.(u9,y)"\/"a) by LATTICE3:14;
      then
A73:  d.(p9,u9) <= (d.(p9,y)"\/"a) "\/" (d.(u9,y)"\/"a) by A72,ORDERS_2:3;
      f.(p,q) = d.(p9,y)"\/"a & f.(q,u) = d.(u9,y)"\/"a by A71,Def4;
      hence thesis by A73,Def4;
    end;
  end;
A74: for p,q,u being Element of new_set2 A st p in A & q in A & u in A holds
  f.(p,u) <= f.(p,q) "\/" f.(q,u)
  proof
    let p,q,u be Element of new_set2 A;
    assume p in A & q in A & u in A;
    then reconsider p9 = p, q9 = q, u9 = u as Element of A;
A75: f.(q,u) = d.(q9,u9) by Def4;
    f.(p,u) = d.(p9,u9) & f.(p,q) = d.(p9,q9) by Def4;
    hence thesis by A3,A75;
  end;
  for p,q,u being Element of new_set2 A holds f.(p,u) <= f.(p,q) "\/" f.
  ( q, u )
  proof
    let p,q,u be Element of new_set2 A;
    per cases by XBOOLE_0:def 3;
    suppose
      p in A & q in A & u in A;
      hence thesis by A74;
    end;
    suppose
      p in A & q in A & u in B;
      hence thesis by A4;
    end;
    suppose
      p in A & q in B & u in A;
      hence thesis by A66;
    end;
    suppose
      p in A & q in B & u in B;
      hence thesis by A13;
    end;
    suppose
      p in B & q in A & u in A;
      hence thesis by A57;
    end;
    suppose
      p in B & q in A & u in B;
      hence thesis by A25;
    end;
    suppose
      p in B & q in B & u in A;
      hence thesis by A45;
    end;
    suppose
      p in B & q in B & u in B;
      hence thesis by A35;
    end;
  end;
  hence thesis;
end;

theorem Th13:
  for A being non empty set for L being lower-bounded LATTICE for
  d be BiFunction of A,L for q be Element of [:A,A,the carrier of L,the carrier
  of L:] holds d c= new_bi_fun2(d,q)
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be Element of [:A,A,the carrier of L,the carrier of L:];
  set g = new_bi_fun2(d,q);
A1: A c= new_set2 A by XBOOLE_1:7;
A2: for z being object st z in dom d holds d.z = g.z
  proof
    let z be object;
    assume
A3: z in dom d;
    then consider x,y being object such that
A4: [x,y] = z by RELAT_1:def 1;
    reconsider x9 = x, y9 = y as Element of A by A3,A4,ZFMISC_1:87;
    d.[x,y] = d.(x9,y9) .= g.(x9,y9) by Def4
      .= g.[x,y];
    hence thesis by A4;
  end;
  dom d = [:A,A:] & dom g = [:new_set2 A,new_set2 A:] by FUNCT_2:def 1;
  then dom d c= dom g by A1,ZFMISC_1:96;
  hence thesis by A2,GRFUNC_1:2;
end;

reserve x for set,
  C for Ordinal,
  L0 for Sequence;

definition
  let A be non empty set;
  let O be Ordinal;
  func ConsecutiveSet2(A,O) -> set means
  :Def5:
  ex L0 being Sequence st it = last
  L0 & dom L0 = succ O & L0.0 = A & (for C being Ordinal st succ C in succ O
  holds L0.succ C = new_set2(L0.C)) & for C being Ordinal st C in succ O & C <>
  0 & C is limit_ordinal holds L0.C = union rng (L0|C);
  correctness
  proof
    deffunc D(set,Sequence) = union rng $2;
    deffunc C(Ordinal,set) = new_set2 $2;
    (ex x being object,L0
   st x = last L0 & dom L0 = succ O & L0.0 = A & (for C st
succ C in succ O holds L0.succ C = C(C,L0.C)) & for C st C in succ O & C <> 0
& C is limit_ordinal holds L0.C = D(C,L0|C) ) & for x1,x2 being set st (ex L0
    st x1 = last L0 & dom L0 = succ O & L0.0 = A & (for C st succ C in succ O
    holds L0.succ C = C(C,L0.C)) & for C st C in succ O & C <> 0 & C is
limit_ordinal holds L0.C = D(C,L0|C) ) & (ex L0 st x2 = last L0 & dom L0 = succ
O & L0.0 = A & (for C st succ C in succ O holds L0.succ C = C(C,L0.C)) & for C
st C in succ O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) ) holds x1
    = x2 from ORDINAL2:sch 7;
   hence thesis;
  end;
end;

theorem Th14:
  for A being non empty set holds ConsecutiveSet2(A,0) = A
proof
  deffunc D(set,Sequence) = union rng $2;
  deffunc C(Ordinal,set) = new_set2 $2;
  let A be non empty set;
  deffunc F(Ordinal) = ConsecutiveSet2(A,$1);
A1: for O being Ordinal, It being object holds It = F(O) iff ex L0 being
Sequence st It = last L0 & dom L0 = succ O & L0.0 = A & (for C being Ordinal
st succ C in succ O holds L0.succ C = C(C,L0.C)) & for C being Ordinal st C in
  succ O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) by Def5;
  thus F(0) = A from ORDINAL2:sch 8(A1);
end;

theorem Th15:
  for A being non empty set for O being Ordinal holds
  ConsecutiveSet2(A,succ O) = new_set2 ConsecutiveSet2(A,O)
proof
  deffunc D(set,Sequence) = union rng $2;
  deffunc C(Ordinal,set) = new_set2 $2;
  let A be non empty set;
  let O be Ordinal;
  deffunc F(Ordinal) = ConsecutiveSet2(A,$1);
A1: for O being Ordinal, It being object holds It = F(O) iff ex L0 being
Sequence st It = last L0 & dom L0 = succ O & L0.0 = A & (for C being Ordinal
st succ C in succ O holds L0.succ C = C(C,L0.C)) & for C being Ordinal st C in
  succ O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) by Def5;
  for O being Ordinal holds F(succ O) = C(O,F(O)) from ORDINAL2:sch 9( A1);
  hence thesis;
end;

theorem Th16:
  for A being non empty set for O being Ordinal for T being
  Sequence holds O <> 0 & O is limit_ordinal & dom T = O & (for O1 being
Ordinal st O1 in O holds T.O1 = ConsecutiveSet2(A,O1)) implies ConsecutiveSet2(
  A,O) = union rng T
proof
  deffunc D(set,Sequence) = union rng $2;
  deffunc C(Ordinal,set) = new_set2 $2;
  let A be non empty set;
  let O be Ordinal;
  let T be Sequence;
  deffunc F(Ordinal) = ConsecutiveSet2(A,$1);
  assume that
A1: O <> 0 & O is limit_ordinal and
A2: dom T = O and
A3: for O1 being Ordinal st O1 in O holds T.O1 = F(O1);
A4: for O being Ordinal, It being object holds It = F(O) iff ex L0 being
Sequence st It = last L0 & dom L0 = succ O & L0.0 = A & (for C being Ordinal
st succ C in succ O holds L0.succ C = C(C,L0.C)) & for C being Ordinal st C in
  succ O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) by Def5;
  thus F(O) = D(O,T) from ORDINAL2:sch 10(A4,A1,A2,A3);
end;

reserve O1,O2 for Ordinal;

registration
  let A be non empty set;
  let O be Ordinal;
  cluster ConsecutiveSet2(A,O) -> non empty;
  coherence
  proof
    defpred X[Ordinal] means ConsecutiveSet2(A,$1) is non empty;
A1: for O1 being Ordinal st X[O1] holds X[succ O1]
    proof
      let O1 be Ordinal;
      assume ConsecutiveSet2(A,O1) is non empty;
      ConsecutiveSet2(A,succ O1) = new_set2 ConsecutiveSet2(A,O1) by Th15;
      hence thesis;
    end;
A2: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[
    O2] holds X[O1]
    proof
      deffunc U(Ordinal) = ConsecutiveSet2(A,$1);
      let O1 be Ordinal;
      assume that
A3:   O1 <> 0 and
A4:   O1 is limit_ordinal and
      for O2 being Ordinal st O2 in O1 holds ConsecutiveSet2(A,O2) is non
      empty;
A5:   {} in O1 by A3,ORDINAL3:8;
      consider Ls being Sequence such that
A6:   dom Ls = O1 & for O2 being Ordinal st O2 in O1 holds Ls.O2 = U(
      O2) from ORDINAL2:sch 2;
      Ls.{} = ConsecutiveSet2(A,{}) by A3,A6,ORDINAL3:8
        .= A by Th14;
      then
A7:   A in rng Ls by A6,A5,FUNCT_1:def 3;
      ConsecutiveSet2(A,O1) = union rng Ls by A3,A4,A6,Th16;
      then A c= ConsecutiveSet2(A,O1) by A7,ZFMISC_1:74;
      hence thesis;
    end;
A8: X[0] by Th14;
    for O being Ordinal holds X[O] from ORDINAL2:sch 1(A8,A1,A2);
    hence thesis;
  end;
end;

theorem Th17:
  for A being non empty set for O being Ordinal holds A c= ConsecutiveSet2(A,O)
proof
  let A be non empty set;
  let O be Ordinal;
  defpred X[Ordinal] means A c= ConsecutiveSet2(A,$1);
A1: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O1 be Ordinal;
    ConsecutiveSet2(A,succ O1) = new_set2 ConsecutiveSet2(A,O1) by Th15;
    then
A2: ConsecutiveSet2(A,O1) c= ConsecutiveSet2(A,succ O1) by XBOOLE_1:7;
    assume A c= ConsecutiveSet2(A,O1);
    hence thesis by A2,XBOOLE_1:1;
  end;
A3: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[O2
  ] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveSet2(A,$1);
    let O2 be Ordinal;
    assume that
A4: O2 <> 0 and
A5: O2 is limit_ordinal and
    for O1 be Ordinal st O1 in O2 holds A c= ConsecutiveSet2(A,O1);
A6: {} in O2 by A4,ORDINAL3:8;
    consider Ls being Sequence such that
A7: dom Ls = O2 & for O1 being Ordinal st O1 in O2 holds Ls.O1 = U(O1)
    from ORDINAL2:sch 2;
    Ls.{} = ConsecutiveSet2(A,{}) by A4,A7,ORDINAL3:8
      .= A by Th14;
    then
A8: A in rng Ls by A7,A6,FUNCT_1:def 3;
    ConsecutiveSet2(A,O2) = union rng Ls by A4,A5,A7,Th16;
    hence thesis by A8,ZFMISC_1:74;
  end;
A9: X[0] by Th14;
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A9,A1,A3);
  hence thesis;
end;

definition
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  let O be Ordinal;
  assume
A1: O in dom q;
  func Quadr2(q,O) -> Element of [:ConsecutiveSet2(A,O),ConsecutiveSet2(A,O),
  the carrier of L,the carrier of L:] equals
  :Def6:
  q.O;
  correctness
  proof
    q.O in rng q by A1,FUNCT_1:def 3;
    then q.O in {[x,y,a,b] where x is Element of A, y is Element of A, a is
    Element of L, b is Element of L: d.(x,y) <= a"\/"b} by LATTICE5:def 13;
    then consider x,y be Element of A, a,b be Element of L such that
A2: q.O = [x,y,a,b] and
    d.(x,y) <= a"\/"b;
    reconsider a,b as Element of L;
    A c= ConsecutiveSet2(A,O) by Th17;
    then reconsider x,y as Element of ConsecutiveSet2(A,O);
    reconsider z = [x,y,a,b] as Element of [:ConsecutiveSet2(A,O),
    ConsecutiveSet2(A,O), the carrier of L,the carrier of L:];
    z = q.O by A2;
    hence thesis;
  end;
end;

definition
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  let O be Ordinal;
  func ConsecutiveDelta2(q,O) -> set means
  :Def7:
  ex L0 being Sequence st it = last
  L0 & dom L0 = succ O & L0.0 = d & (for C being Ordinal st succ C in succ O
holds L0.succ C = new_bi_fun2(BiFun(L0.C,ConsecutiveSet2(A,C),L),Quadr2(q,C)))
& for C being Ordinal st C in succ O & C <> 0 & C is limit_ordinal holds L0.C
  = union rng(L0|C);
  correctness
  proof
    deffunc D(set,Sequence) = union rng $2;
    deffunc C(Ordinal,set) = new_bi_fun2(BiFun($2,ConsecutiveSet2(A,$1),L),
    Quadr2(q,$1));
     (ex x being object,L0
 st x = last L0 & dom L0 = succ O & L0.0 = d & (for C st
succ C in succ O holds L0.succ C = C(C,L0.C)) & for C st C in succ O & C <> 0
& C is limit_ordinal holds L0.C = D(C,L0|C)) & for x1,x2 being set st (ex L0 st
x1 = last L0 & dom L0 = succ O & L0.0= d & (for C st succ C in succ O holds
L0.succ C = C(C,L0.C)) & for C st C in succ O & C <> 0 & C is limit_ordinal
holds L0.C = D(C,L0|C) ) & (ex L0 st x2 = last L0 & dom L0 = succ O & L0.0 = d
& (for C st succ C in succ O holds L0.succ C = C(C,L0.C)) & for C st C in succ
O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) ) holds x1 = x2 from
    ORDINAL2:sch 7;
   hence thesis;
  end;
end;

theorem Th18:
  for A being non empty set for L be lower-bounded LATTICE for d
being BiFunction of A,L for q being QuadrSeq of d holds ConsecutiveDelta2(q,0)
  = d
proof
  deffunc D(set,Sequence) = union rng $2;
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  deffunc C(Ordinal,set) = new_bi_fun2(BiFun($2,ConsecutiveSet2(A,$1),L),
  Quadr2(q,$1));
  deffunc F(Ordinal) = ConsecutiveDelta2(q,$1);
A1: for O being Ordinal, It being object holds It = F(O) iff ex L0 being
Sequence st It = last L0 & dom L0 = succ O & L0.0 = d & (for C being Ordinal
st succ C in succ O holds L0.succ C = C(C,L0.C)) & for C being Ordinal st C in
  succ O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) by Def7;
  thus F(0) = d from ORDINAL2:sch 8(A1);
end;

theorem Th19:
  for A being non empty set for L be lower-bounded LATTICE for d
  be BiFunction of A,L for q being QuadrSeq of d for O being Ordinal holds
  ConsecutiveDelta2(q,succ O) = new_bi_fun2(BiFun(ConsecutiveDelta2(q,O),
  ConsecutiveSet2(A,O),L),Quadr2(q,O))
proof
  deffunc D(set,Sequence) = union rng $2;
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  let O be Ordinal;
  deffunc C(Ordinal,set) = new_bi_fun2(BiFun($2,ConsecutiveSet2(A,$1),L),
  Quadr2(q,$1));
  deffunc F(Ordinal) = ConsecutiveDelta2(q,$1);
A1: for O being Ordinal, It being object holds It = F(O) iff ex L0 being
Sequence st It = last L0 & dom L0 = succ O & L0.0 = d & (for C being Ordinal
st succ C in succ O holds L0.succ C = C(C,L0.C)) & for C being Ordinal st C in
  succ O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) by Def7;
  for O being Ordinal holds F(succ O) = C(O,F(O)) from ORDINAL2:sch 9( A1);
  hence thesis;
end;

theorem Th20:
  for A being non empty set for L be lower-bounded LATTICE for d
  be BiFunction of A,L for q being QuadrSeq of d for T being Sequence for O
  being Ordinal holds O <> 0 & O is limit_ordinal & dom T = O & (for O1 being
  Ordinal st O1 in O holds T.O1 = ConsecutiveDelta2(q,O1)) implies
  ConsecutiveDelta2(q,O) = union rng T
proof
  deffunc D(set,Sequence) = union rng $2;
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  let T be Sequence;
  let O be Ordinal;
  deffunc C(Ordinal,set) = new_bi_fun2(BiFun($2,ConsecutiveSet2(A,$1),L),
  Quadr2(q,$1));
  deffunc F(Ordinal) = ConsecutiveDelta2(q,$1);
  assume that
A1: O <> 0 & O is limit_ordinal and
A2: dom T = O and
A3: for O1 being Ordinal st O1 in O holds T.O1 = F(O1);
A4: for O being Ordinal, It being object holds It = F(O) iff ex L0 being
Sequence st It = last L0 & dom L0 = succ O & L0.0 = d & (for C being Ordinal
st succ C in succ O holds L0.succ C = C(C,L0.C) ) & for C being Ordinal st C in
  succ O & C <> 0 & C is limit_ordinal holds L0.C = D(C,L0|C) by Def7;
  thus F(O) = D(O,T) from ORDINAL2:sch 10(A4,A1,A2,A3);
end;

theorem Th21:
  for A being non empty set for O,O1,O2 being Ordinal holds O1 c=
  O2 implies ConsecutiveSet2(A,O1) c= ConsecutiveSet2(A,O2)
proof
  let A be non empty set;
  let O,O1,02 be Ordinal;
  defpred X[Ordinal] means O1 c= $1 implies ConsecutiveSet2(A,O1) c=
  ConsecutiveSet2(A,$1);
A1: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O2 be Ordinal;
    assume
A2: O1 c= O2 implies ConsecutiveSet2(A,O1) c= ConsecutiveSet2(A,O2);
    assume
A3: O1 c= succ O2;
    per cases;
    suppose
      O1 = succ O2;
      hence thesis;
    end;
    suppose
      O1 <> succ O2;
      then O1 c< succ O2 by A3;
      then
A4:   O1 in succ O2 by ORDINAL1:11;
      ConsecutiveSet2(A,O2) c= new_set2 ConsecutiveSet2(A,O2) by XBOOLE_1:7;
      then ConsecutiveSet2(A,O1) c= new_set2 ConsecutiveSet2(A,O2) by A2,A4,
ORDINAL1:22;
      hence thesis by Th15;
    end;
  end;
A5: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[
  O2] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveSet2(A,$1);
    let O2 be Ordinal;
    assume that
A6: O2 <> 0 & O2 is limit_ordinal and
    for O3 being Ordinal st O3 in O2 holds O1 c= O3 implies
    ConsecutiveSet2(A,O1) c= ConsecutiveSet2(A,O3);
    consider L being Sequence such that
A7: dom L = O2 & for O3 being Ordinal st O3 in O2 holds L.O3 = U(O3)
    from ORDINAL2:sch 2;
A8: ConsecutiveSet2(A,O2) = union rng L by A6,A7,Th16;
    assume
A9: O1 c= O2;
    per cases;
    suppose
      O1 = O2;
      hence thesis;
    end;
    suppose
      O1 <> O2;
      then
A10:  O1 c< O2 by A9;
      then O1 in O2 by ORDINAL1:11;
      then
A11:  L.O1 in rng L by A7,FUNCT_1:def 3;
      L.O1 = ConsecutiveSet2(A,O1) by A7,A10,ORDINAL1:11;
      hence thesis by A8,A11,ZFMISC_1:74;
    end;
  end;
A12: X[0];
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A12,A1,A5);
  hence thesis;
end;

theorem Th22:
  for A being non empty set for L be lower-bounded LATTICE for d
  be BiFunction of A,L for q being QuadrSeq of d for O being Ordinal holds
  ConsecutiveDelta2(q,O) is BiFunction of ConsecutiveSet2(A,O),L
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  let O be Ordinal;
  defpred X[Ordinal] means ConsecutiveDelta2(q,$1) is BiFunction of
  ConsecutiveSet2(A,$1),L;
A1: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O1 be Ordinal;
    assume ConsecutiveDelta2(q,O1) is BiFunction of ConsecutiveSet2(A,O1),L;
    then reconsider
    CD = ConsecutiveDelta2(q,O1) as BiFunction of ConsecutiveSet2(A
    ,O1),L;
A2: ConsecutiveDelta2(q,succ O1) = new_bi_fun2(BiFun(ConsecutiveDelta2( q,
    O1 ) , ConsecutiveSet2(A,O1),L),Quadr2(q,O1)) by Th19
      .= new_bi_fun2(CD,Quadr2(q,O1)) by LATTICE5:def 15;
    ConsecutiveSet2(A,succ O1) = new_set2 ConsecutiveSet2(A,O1) by Th15;
    hence thesis by A2;
  end;
A3: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[O2
  ] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveDelta2(q,$1);
    let O1 be Ordinal;
    assume that
A4: O1 <> 0 and
A5: O1 is limit_ordinal and
A6: for O2 be Ordinal st O2 in O1 holds ConsecutiveDelta2(q,O2) is
    BiFunction of ConsecutiveSet2(A,O2),L;
    reconsider o1 = O1 as non empty Ordinal by A4;
    set YY = the set of all
 [:ConsecutiveSet2(A,O2),ConsecutiveSet2(A,O2):] where O2 is
    Element of o1 ;
    consider Ls being Sequence such that
A7: dom Ls = O1 & for O2 being Ordinal st O2 in O1 holds Ls.O2 = U(O2
    ) from ORDINAL2:sch 2;
A8: for O,O2 being Ordinal st O c= O2 & O2 in dom Ls holds Ls.O c= Ls.O2
    proof
      let O be Ordinal;
      defpred X[Ordinal] means O c= $1 & $1 in dom Ls implies Ls.O c= Ls.$1;
A9:   for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds
      X[O2] holds X[O1]
      proof
        deffunc U(Ordinal) = ConsecutiveDelta2(q,$1);
        let O2 be Ordinal;
        assume that
A10:    O2 <> 0 & O2 is limit_ordinal and
        for O3 be Ordinal st O3 in O2 holds O c= O3 & O3 in dom Ls implies
        Ls.O c= Ls.O3;
        assume that
A11:    O c= O2 and
A12:    O2 in dom Ls;
        consider Lt being Sequence such that
A13:    dom Lt = O2 & for O3 being Ordinal st O3 in O2 holds Lt.O3 =
        U(O3) from ORDINAL2:sch 2;
A14:    Ls.O2 = ConsecutiveDelta2(q,O2) by A7,A12
          .= union rng Lt by A10,A13,Th20;
        per cases;
        suppose
          O = O2;
          hence thesis;
        end;
        suppose
          O <> O2;
          then
A15:      O c< O2 by A11;
          then
A16:      O in O2 by ORDINAL1:11;
          then Ls.O = ConsecutiveDelta2(q,O) by A7,A12,ORDINAL1:10
            .= Lt.O by A13,A15,ORDINAL1:11;
          then Ls.O in rng Lt by A13,A16,FUNCT_1:def 3;
          hence thesis by A14,ZFMISC_1:74;
        end;
      end;
A17:  for O1 being Ordinal st X[O1] holds X[succ O1]
      proof
        let O2 be Ordinal;
        assume
A18:    O c= O2 & O2 in dom Ls implies Ls.O c= Ls.O2;
        assume that
A19:    O c= succ O2 and
A20:    succ O2 in dom Ls;
        per cases;
        suppose
          O = succ O2;
          hence thesis;
        end;
        suppose
          O <> succ O2;
          then O c< succ O2 by A19;
          then
A21:      O in succ O2 by ORDINAL1:11;
A22:      O2 in succ O2 by ORDINAL1:6;
          then O2 in dom Ls by A20,ORDINAL1:10;
          then reconsider Def8 = ConsecutiveDelta2(q,O2) as BiFunction of
          ConsecutiveSet2(A,O2),L by A6,A7;
          Ls.succ O2 = ConsecutiveDelta2(q,succ O2) by A7,A20
            .= new_bi_fun2(BiFun(ConsecutiveDelta2(q,O2), ConsecutiveSet2(A,
          O2),L),Quadr2(q,O2)) by Th19
            .= new_bi_fun2(Def8,Quadr2(q,O2)) by LATTICE5:def 15;
          then ConsecutiveDelta2(q,O2) c= Ls.succ O2 by Th13;
          then Ls.O2 c= Ls.succ O2 by A7,A20,A22,ORDINAL1:10;
          hence thesis by A18,A20,A21,A22,ORDINAL1:10,22;
        end;
      end;
A23:  X[0];
      thus for O being Ordinal holds X[O] from ORDINAL2:sch 1(A23,A17, A9);
    end;
    for x,y being set st x in rng Ls & y in rng Ls holds x,y are_c=-comparable
    proof
      let x,y be set;
      assume that
A24:  x in rng Ls and
A25:  y in rng Ls;
      consider o1 being object such that
A26:  o1 in dom Ls and
A27:  Ls.o1 = x by A24,FUNCT_1:def 3;
      consider o2 being object such that
A28:  o2 in dom Ls and
A29:  Ls.o2 = y by A25,FUNCT_1:def 3;
      reconsider o19 = o1, o29 = o2 as Ordinal by A26,A28;
      o19 c= o29 or o29 c= o19;
      then x c= y or y c= x by A8,A26,A27,A28,A29;
      hence thesis;
    end;
    then
A30: rng Ls is c=-linear;
    set Y = the carrier of L, X = [:
    ConsecutiveSet2(A,O1),ConsecutiveSet2(A,O1):], f = union rng Ls;
    rng Ls c= PFuncs(X,Y)
    proof
      let z be object;
      assume z in rng Ls;
      then consider o being object such that
A31:  o in dom Ls and
A32:  z = Ls.o by FUNCT_1:def 3;
      reconsider o as Ordinal by A31;
      Ls.o = ConsecutiveDelta2(q,o) by A7,A31;
      then reconsider
      h = Ls.o as BiFunction of ConsecutiveSet2(A,o),L by A6,A7,A31;
      o c= O1 by A7,A31,ORDINAL1:def 2;
      then dom h = [:ConsecutiveSet2(A,o),ConsecutiveSet2(A,o):] &
      ConsecutiveSet2(A,o) c= ConsecutiveSet2(A,O1) by Th21,FUNCT_2:def 1;
      then rng h c= Y & dom h c= X by ZFMISC_1:96;
      hence thesis by A32,PARTFUN1:def 3;
    end;
    then f in PFuncs(X,Y) by A30,TREES_2:40;
    then
A33: ex g being Function st f = g & dom g c= X & rng g c= Y by PARTFUN1:def 3;
    Ls is Function-yielding
    proof
      let x be object;
      assume
A34:  x in dom Ls;
      then reconsider o = x as Ordinal;
      Ls.o = ConsecutiveDelta2(q,o) by A7,A34;
      hence thesis by A6,A7,A34;
    end;
    then reconsider LsF = Ls as Function-yielding Function;
A35: rng doms LsF = YY
    proof
      thus rng doms LsF c= YY
      proof
        let Z be object;
        assume Z in rng doms LsF;
        then consider o being object such that
A36:    o in dom doms LsF and
A37:    Z = (doms LsF).o by FUNCT_1:def 3;
A38:    o in dom LsF by A36,FUNCT_6:59;
        then reconsider o9 = o as Element of o1 by A7;
        Ls.o9 = ConsecutiveDelta2(q,o9) by A7;
        then reconsider
        ls = Ls.o9 as BiFunction of ConsecutiveSet2(A,o9),L by A6;
        Z = dom ls by A37,A38,FUNCT_6:22
          .= [:ConsecutiveSet2(A,o9),ConsecutiveSet2(A,o9):] by FUNCT_2:def 1;
        hence thesis;
      end;
      let Z be object;
      assume Z in YY;
      then consider o being Element of o1 such that
A39:  Z = [:ConsecutiveSet2(A,o),ConsecutiveSet2(A,o):];
      Ls.o = ConsecutiveDelta2(q,o) by A7;
      then reconsider ls = Ls.o as BiFunction of ConsecutiveSet2(A,o),L by A6;
      o in dom LsF by A7;
      then
A40:  o in dom doms LsF by FUNCT_6:59;
      Z = dom ls by A39,FUNCT_2:def 1
        .= (doms LsF).o by A7,FUNCT_6:22;
      hence thesis by A40,FUNCT_1:def 3;
    end;
A41: ConsecutiveDelta2(q,O1) = union rng Ls by A4,A5,A7,Th20;
    reconsider f as Function by A33;
    deffunc U(Ordinal) = ConsecutiveSet2(A,$1);
    consider Ts being Sequence such that
A42: dom Ts = O1 & for O2 being Ordinal st O2 in O1 holds Ts.O2 = U(O2
    ) from ORDINAL2:sch 2;
    {} in O1 by A4,ORDINAL3:8;
    then reconsider RTs = rng Ts as non empty set by A42,FUNCT_1:3;
A43: YY = { [:a,a:] where a is Element of RTs : a in RTs }
    proof
      set XX = { [:a,a:] where a is Element of RTs : a in RTs };
      thus YY c= XX
      proof
        let Z be object;
        assume Z in YY;
        then consider o being Element of o1 such that
A44:    Z = [:ConsecutiveSet2(A,o),ConsecutiveSet2(A,o):];
        Ts.o = ConsecutiveSet2(A,o) by A42;
        then reconsider CoS = ConsecutiveSet2(A,o) as Element of RTs by A42,
FUNCT_1:def 3;
        Z = [:CoS,CoS:] by A44;
        hence thesis;
      end;
      let Z be object;
      assume Z in XX;
      then consider a being Element of RTs such that
A45:  Z = [:a,a:] and
      a in RTs;
      consider o being object such that
A46:  o in dom Ts and
A47:  a = Ts.o by FUNCT_1:def 3;
      reconsider o9 = o as Ordinal by A46;
      a = ConsecutiveSet2(A,o9) by A42,A46,A47;
      hence thesis by A42,A45,A46;
    end;
    for x,y being set st x in RTs & y in RTs holds x,y are_c=-comparable
    proof
      let x,y be set;
      assume that
A48:  x in RTs and
A49:  y in RTs;
      consider o1 being object such that
A50:  o1 in dom Ts and
A51:  Ts.o1 = x by A48,FUNCT_1:def 3;
      consider o2 being object such that
A52:  o2 in dom Ts and
A53:  Ts.o2 = y by A49,FUNCT_1:def 3;
      reconsider o19 = o1, o29 = o2 as Ordinal by A50,A52;
A54:  Ts.o29 = ConsecutiveSet2(A,o29) by A42,A52;
A55:  o19 c= o29 or o29 c= o19;
      Ts.o19 = ConsecutiveSet2(A,o19) by A42,A50;
      then x c= y or y c= x by A51,A53,A54,A55,Th21;
      hence thesis;
    end;
    then
A56: dom f = union rng doms LsF & RTs is c=-linear by LATTICE5:1;
    X = [:union rng Ts, ConsecutiveSet2(A,O1):] by A4,A5,A42,Th16
      .= [:union RTs, union RTs :] by A4,A5,A42,Th16
      .= dom f by A35,A56,A43,LATTICE5:3;
    hence thesis by A41,A33,FUNCT_2:def 1,RELSET_1:4;
  end;
  ConsecutiveSet2(A,{}) = A by Th14;
  then
A57: X[0] by Th18;
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A57,A1,A3);
  hence thesis;
end;

definition
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  let O be Ordinal;
  redefine func ConsecutiveDelta2(q,O) -> BiFunction of ConsecutiveSet2(A,O),L;  :: redefines ConsecutiveDelta2 (LATTICE8, definition)
  coherence by Th22;
end;

theorem Th23:
  for A being non empty set for L be lower-bounded LATTICE for d
  be BiFunction of A,L for q being QuadrSeq of d for O being Ordinal holds d c=
  ConsecutiveDelta2(q,O)
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  let O be Ordinal;
  defpred X[Ordinal] means d c= ConsecutiveDelta2(q,$1);
A1: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O1 be Ordinal;
    ConsecutiveDelta2(q,succ O1) = new_bi_fun2(BiFun(ConsecutiveDelta2( q,
    O1 ) , ConsecutiveSet2(A,O1),L),Quadr2(q,O1)) by Th19
      .= new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1)) by LATTICE5:def 15;
    then
A2: ConsecutiveDelta2(q,O1) c= ConsecutiveDelta2(q,succ O1) by Th13;
    assume d c= ConsecutiveDelta2(q,O1);
    hence thesis by A2,XBOOLE_1:1;
  end;
A3: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[O2
  ] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveDelta2(q,$1);
    let O2 be Ordinal;
    assume that
A4: O2 <> 0 and
A5: O2 is limit_ordinal and
    for O1 be Ordinal st O1 in O2 holds d c= ConsecutiveDelta2(q,O1);
A6: {} in O2 by A4,ORDINAL3:8;
    consider Ls being Sequence such that
A7: dom Ls = O2 & for O1 being Ordinal st O1 in O2 holds Ls.O1 = U(O1)
    from ORDINAL2:sch 2;
    Ls.{} = ConsecutiveDelta2(q,{}) by A4,A7,ORDINAL3:8
      .= d by Th18;
    then
A8: d in rng Ls by A7,A6,FUNCT_1:def 3;
    ConsecutiveDelta2(q,O2) = union rng Ls by A4,A5,A7,Th20;
    hence thesis by A8,ZFMISC_1:74;
  end;
A9: X[0] by Th18;
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A9,A1,A3);
  hence thesis;
end;

theorem Th24:
  for A being non empty set for L be lower-bounded LATTICE for d
being BiFunction of A,L for O1,O2 being Ordinal for q being QuadrSeq of d st O1
  c= O2 holds ConsecutiveDelta2(q,O1) c= ConsecutiveDelta2(q,O2)
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let O1,O2 be Ordinal;
  let q be QuadrSeq of d;
  defpred X[Ordinal] means O1 c= $1 implies ConsecutiveDelta2(q,O1) c=
  ConsecutiveDelta2(q,$1);
A1: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[
  O2] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveDelta2(q,$1);
    let O2 be Ordinal;
    assume that
A2: O2 <> 0 & O2 is limit_ordinal and
    for O3 be Ordinal st O3 in O2 holds O1 c= O3 implies ConsecutiveDelta2
    (q,O1) c= ConsecutiveDelta2(q,O3);
    consider L being Sequence such that
A3: dom L = O2 & for O3 being Ordinal st O3 in O2 holds L.O3 = U(O3)
    from ORDINAL2:sch 2;
A4: ConsecutiveDelta2(q,O2) = union rng L by A2,A3,Th20;
    assume
A5: O1 c= O2;
    per cases;
    suppose
      O1 = O2;
      hence thesis;
    end;
    suppose
      O1 <> O2;
      then
A6:   O1 c< O2 by A5;
      then O1 in O2 by ORDINAL1:11;
      then
A7:   L.O1 in rng L by A3,FUNCT_1:def 3;
      L.O1 = ConsecutiveDelta2(q,O1) by A3,A6,ORDINAL1:11;
      hence thesis by A4,A7,ZFMISC_1:74;
    end;
  end;
A8: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O2 be Ordinal;
    assume
A9: O1 c= O2 implies ConsecutiveDelta2(q,O1) c= ConsecutiveDelta2(q,O2 );
    assume
A10: O1 c= succ O2;
    per cases;
    suppose
      O1 = succ O2;
      hence thesis;
    end;
    suppose
A11:  O1 <> succ O2;
      ConsecutiveDelta2(q,succ O2) = new_bi_fun2(BiFun(ConsecutiveDelta2(q
      ,O2), ConsecutiveSet2(A,O2),L),Quadr2(q,O2)) by Th19
        .= new_bi_fun2(ConsecutiveDelta2(q,O2),Quadr2(q,O2)) by LATTICE5:def 15
;
      then
A12:  ConsecutiveDelta2(q,O2) c= ConsecutiveDelta2(q,succ O2) by Th13;
      O1 c< succ O2 by A10,A11;
      then O1 in succ O2 by ORDINAL1:11;
      hence thesis by A9,A12,ORDINAL1:22;
    end;
  end;
A13: X[0];
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A13,A8,A1);
  hence thesis;
end;

theorem Th25:
  for A being non empty set for L be lower-bounded LATTICE for d
  be BiFunction of A,L st d is zeroed for q being QuadrSeq of d for O being
  Ordinal holds ConsecutiveDelta2(q,O) is zeroed
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  assume
A1: d is zeroed;
  let q be QuadrSeq of d;
  let O be Ordinal;
  defpred X[Ordinal] means ConsecutiveDelta2(q,$1) is zeroed;
A2: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O1 be Ordinal;
    assume ConsecutiveDelta2(q,O1) is zeroed;
    then
A3: new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1)) is zeroed by Th10;
    let z be Element of ConsecutiveSet2(A,succ O1);
    reconsider z9 = z as Element of new_set2 ConsecutiveSet2(A,O1) by Th15;
    ConsecutiveDelta2(q,succ O1) = new_bi_fun2(BiFun(ConsecutiveDelta2(q,
    O1 ) , ConsecutiveSet2(A,O1),L),Quadr2(q,O1)) by Th19
      .= new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1)) by LATTICE5:def 15;
    hence
    ConsecutiveDelta2(q,succ O1).(z,z) = new_bi_fun2(ConsecutiveDelta2(q,
    O1),Quadr2(q,O1)).(z9,z9)
      .= Bottom L by A3;
  end;
A4: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[O2
  ] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveDelta2(q,$1);
    let O2 be Ordinal;
    assume that
A5: O2 <> 0 & O2 is limit_ordinal and
A6: for O1 be Ordinal st O1 in O2 holds ConsecutiveDelta2(q,O1) is zeroed;
    set CS = ConsecutiveSet2(A,O2);
    consider Ls being Sequence such that
A7: dom Ls = O2 & for O1 being Ordinal st O1 in O2 holds Ls.O1 = U(O1
    ) from ORDINAL2:sch 2;
    ConsecutiveDelta2(q,O2) = union rng Ls by A5,A7,Th20;
    then reconsider f = union rng Ls as BiFunction of CS,L;
    deffunc U(Ordinal) = ConsecutiveSet2(A,$1);
    consider Ts being Sequence such that
A8: dom Ts = O2 & for O1 being Ordinal st O1 in O2 holds Ts.O1 = U(O1
    ) from ORDINAL2:sch 2;
A9: ConsecutiveSet2(A,O2) = union rng Ts by A5,A8,Th16;
    f is zeroed
    proof
      let x be Element of CS;
      consider y being set such that
A10:  x in y and
A11:  y in rng Ts by A9,TARSKI:def 4;
      consider o being object such that
A12:  o in dom Ts and
A13:  y = Ts.o by A11,FUNCT_1:def 3;
      reconsider o as Ordinal by A12;
A14:  Ls.o = ConsecutiveDelta2(q,o) by A7,A8,A12;
      then reconsider h = Ls.o as BiFunction of ConsecutiveSet2(A,o),L;
      reconsider x9 = x as Element of ConsecutiveSet2(A,o) by A8,A10,A12,A13;
A15:  dom h = [:ConsecutiveSet2(A,o),ConsecutiveSet2(A,o):] by FUNCT_2:def 1;
A16:  h is zeroed
      proof
        let z be Element of ConsecutiveSet2(A,o);
A17:    ConsecutiveDelta2(q,o) is zeroed by A6,A8,A12;
        thus h.(z,z) = ConsecutiveDelta2(q,o).(z,z) by A7,A8,A12
          .= Bottom L by A17;
      end;
      ConsecutiveDelta2(q,o) in rng Ls by A7,A8,A12,A14,FUNCT_1:def 3;
      then
A18:  h c= f by A14,ZFMISC_1:74;
      x in ConsecutiveSet2(A,o) by A8,A10,A12,A13;
      then [x,x] in dom h by A15,ZFMISC_1:87;
      hence f.(x,x) = h.(x9,x9) by A18,GRFUNC_1:2
        .= Bottom L by A16;
    end;
    hence thesis by A5,A7,Th20;
  end;
A19: X[0]
  proof
    let z be Element of ConsecutiveSet2(A,0);
    reconsider z9 = z as Element of A by Th14;
    thus ConsecutiveDelta2(q,0).(z,z) = d.(z9,z9) by Th18
      .= Bottom L by A1;
  end;
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A19,A2,A4);
  hence thesis;
end;

theorem Th26:
  for A being non empty set for L be lower-bounded LATTICE for d
  be BiFunction of A,L st d is symmetric for q being QuadrSeq of d for O being
  Ordinal holds ConsecutiveDelta2(q,O) is symmetric
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  assume
A1: d is symmetric;
  let q be QuadrSeq of d;
  let O be Ordinal;
  defpred X[Ordinal] means ConsecutiveDelta2(q,$1) is symmetric;
A2: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O1 be Ordinal;
    assume ConsecutiveDelta2(q,O1) is symmetric;
    then
A3: new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1)) is symmetric by Th11;
    let x,y be Element of ConsecutiveSet2(A,succ O1);
    reconsider x9=x, y9=y as Element of new_set2 ConsecutiveSet2(A,O1) by Th15;
A4: ConsecutiveDelta2(q,succ O1) = new_bi_fun2(BiFun(ConsecutiveDelta2(q,
    O1), ConsecutiveSet2(A,O1),L),Quadr2(q,O1)) by Th19
      .= new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1)) by LATTICE5:def 15;
    hence
    ConsecutiveDelta2(q,succ O1).(x,y) = new_bi_fun2(ConsecutiveDelta2(q,
    O1),Quadr2(q,O1)).(y9,x9) by A3
      .= ConsecutiveDelta2(q,succ O1).(y,x) by A4;
  end;
A5: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[O2
  ] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveDelta2(q,$1);
    let O2 be Ordinal;
    assume that
A6: O2 <> 0 & O2 is limit_ordinal and
A7: for O1 being Ordinal st O1 in O2 holds ConsecutiveDelta2(q,O1) is
    symmetric;
    set CS = ConsecutiveSet2(A,O2);
    consider Ls being Sequence such that
A8: dom Ls = O2 & for O1 being Ordinal st O1 in O2 holds Ls.O1 = U(O1
    ) from ORDINAL2:sch 2;
    ConsecutiveDelta2(q,O2) = union rng Ls by A6,A8,Th20;
    then reconsider f = union rng Ls as BiFunction of CS,L;
    deffunc U(Ordinal) = ConsecutiveSet2(A,$1);
    consider Ts being Sequence such that
A9: dom Ts = O2 & for O1 being Ordinal st O1 in O2 holds Ts.O1 = U(O1
    ) from ORDINAL2:sch 2;
A10: ConsecutiveSet2(A,O2) = union rng Ts by A6,A9,Th16;
    f is symmetric
    proof
      let x,y be Element of CS;
      consider x1 being set such that
A11:  x in x1 and
A12:  x1 in rng Ts by A10,TARSKI:def 4;
      consider o1 being object such that
A13:  o1 in dom Ts and
A14:  x1 = Ts.o1 by A12,FUNCT_1:def 3;
      consider y1 being set such that
A15:  y in y1 and
A16:  y1 in rng Ts by A10,TARSKI:def 4;
      consider o2 being object such that
A17:  o2 in dom Ts and
A18:  y1 = Ts.o2 by A16,FUNCT_1:def 3;
      reconsider o1,o2 as Ordinal by A13,A17;
A19:  x in ConsecutiveSet2(A,o1) by A9,A11,A13,A14;
A20:  Ls.o1 = ConsecutiveDelta2(q,o1) by A8,A9,A13;
      then reconsider h1 = Ls.o1 as BiFunction of ConsecutiveSet2(A,o1),L;
A21:  h1 is symmetric
      proof
        let x,y be Element of ConsecutiveSet2(A,o1);
A22:    ConsecutiveDelta2(q,o1) is symmetric by A7,A9,A13;
        thus h1.(x,y) = ConsecutiveDelta2(q,o1).(x,y) by A8,A9,A13
          .= ConsecutiveDelta2(q,o1).(y,x) by A22
          .= h1.(y,x) by A8,A9,A13;
      end;
A23:  dom h1 = [:ConsecutiveSet2(A,o1),ConsecutiveSet2(A,o1):] by FUNCT_2:def 1
;
A24:  y in ConsecutiveSet2(A,o2) by A9,A15,A17,A18;
A25:  Ls.o2 = ConsecutiveDelta2(q,o2) by A8,A9,A17;
      then reconsider h2 = Ls.o2 as BiFunction of ConsecutiveSet2(A,o2),L;
A26:  h2 is symmetric
      proof
        let x,y be Element of ConsecutiveSet2(A,o2);
A27:    ConsecutiveDelta2(q,o2) is symmetric by A7,A9,A17;
        thus h2.(x,y) = ConsecutiveDelta2(q,o2).(x,y) by A8,A9,A17
          .= ConsecutiveDelta2(q,o2).(y,x) by A27
          .= h2.(y,x) by A8,A9,A17;
      end;
A28:  dom h2 = [:ConsecutiveSet2(A,o2),ConsecutiveSet2(A,o2):] by FUNCT_2:def 1
;
      per cases;
      suppose
        o1 c= o2;
        then
A29:    ConsecutiveSet2(A,o1) c= ConsecutiveSet2(A,o2) by Th21;
        then
A30:    [y,x] in dom h2 by A19,A24,A28,ZFMISC_1:87;
        ConsecutiveDelta2(q,o2) in rng Ls by A8,A9,A17,A25,FUNCT_1:def 3;
        then
A31:    h2 c= f by A25,ZFMISC_1:74;
        reconsider x9=x, y9=y as Element of ConsecutiveSet2(A,o2) by A9,A15,A17
,A18,A19,A29;
        [x,y] in dom h2 by A19,A24,A28,A29,ZFMISC_1:87;
        hence f.(x,y) = h2.(x9,y9) by A31,GRFUNC_1:2
          .= h2.(y9,x9) by A26
          .= f.(y,x) by A31,A30,GRFUNC_1:2;
      end;
      suppose
        o2 c= o1;
        then
A32:    ConsecutiveSet2(A,o2) c= ConsecutiveSet2(A,o1) by Th21;
        then
A33:    [y,x] in dom h1 by A19,A24,A23,ZFMISC_1:87;
        ConsecutiveDelta2(q,o1) in rng Ls by A8,A9,A13,A20,FUNCT_1:def 3;
        then
A34:    h1 c= f by A20,ZFMISC_1:74;
        reconsider x9=x, y9=y as Element of ConsecutiveSet2(A,o1) by A9,A11,A13
,A14,A24,A32;
        [x,y] in dom h1 by A19,A24,A23,A32,ZFMISC_1:87;
        hence f.(x,y) = h1.(x9,y9) by A34,GRFUNC_1:2
          .= h1.(y9,x9) by A21
          .= f.(y,x) by A34,A33,GRFUNC_1:2;
      end;
    end;
    hence thesis by A6,A8,Th20;
  end;
A35: X[0]
  proof
    let x,y be Element of ConsecutiveSet2(A,0);
    reconsider x9 = x, y9 = y as Element of A by Th14;
    thus ConsecutiveDelta2(q,0).(x,y) = d.(x9,y9) by Th18
      .= d.(y9,x9) by A1
      .= ConsecutiveDelta2(q,0).(y,x) by Th18;
  end;
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A35,A2,A5);
  hence thesis;
end;

theorem Th27:
  for A being non empty set for L being lower-bounded LATTICE st L
  is modular for d be BiFunction of A,L st d is symmetric u.t.i. for O being
Ordinal for q being QuadrSeq of d st O c= DistEsti(d) holds ConsecutiveDelta2(q
  ,O) is u.t.i.
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  assume
A1: L is modular;
  let d be BiFunction of A,L;
  assume that
A2: d is symmetric and
A3: d is u.t.i.;
  let O be Ordinal;
  let q be QuadrSeq of d;
  defpred X[Ordinal] means $1 c= DistEsti(d) implies ConsecutiveDelta2(q,$1)
  is u.t.i.;
A4: for O1 being Ordinal st X[O1] holds X[succ O1]
  proof
    let O1 be Ordinal;
    assume that
A5: O1 c= DistEsti(d) implies ConsecutiveDelta2(q,O1) is u.t.i. and
A6: succ O1 c= DistEsti(d);
A7: O1 in DistEsti(d) by A6,ORDINAL1:21;
    then
A8: O1 in dom q by LATTICE5:25;
    then q.O1 in rng q by FUNCT_1:def 3;
    then
A9: q.O1 in {[u,v,a9,b9] where u is Element of A, v is Element of A, a9
    is Element of L, b9 is Element of L: d.(u,v) <= a9"\/"b9} by
LATTICE5:def 13;
    let x,y,z be Element of ConsecutiveSet2(A,succ O1);
A10: ConsecutiveDelta2(q,O1) is symmetric by A2,Th26;
    reconsider x9 = x, y9 = y, z9 = z as Element of new_set2 ConsecutiveSet2(A
    ,O1) by Th15;
    set f = new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1));
    set X = Quadr2(q,O1)`1_4, Y = Quadr2(q,O1)`2_4;
    reconsider a = Quadr2(q,O1)`3_4, b = Quadr2(q,O1)`4_4 as Element of L;
A11: dom d = [:A,A:] & d c= ConsecutiveDelta2(q,O1) by Th23,FUNCT_2:def 1;
    consider u,v be Element of A, a9,b9 be Element of L such that
A12: q.O1 = [u,v,a9,b9] and
A13: d.(u,v) <= a9"\/"b9 by A9;
A14: Quadr2(q,O1) = [u,v,a9,b9] by A8,A12,Def6;
    then
A15: u = X & v = Y;
A16: a9 = a & b9 = b by A14;
    d.(u,v) = d.[u,v] .= ConsecutiveDelta2(q,O1).(X,Y) by A15,A11,GRFUNC_1:2;
    then
    new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1)) is u.t.i. by A1,A5,A7,A10
,A13,A16,Th12,ORDINAL1:def 2;
    then
A17: f.(x9,z9) <= f.(x9,y9) "\/" f.(y9,z9);
    ConsecutiveDelta2(q,succ O1) = new_bi_fun2(BiFun(ConsecutiveDelta2(q,
    O1), ConsecutiveSet2(A,O1),L),Quadr2(q,O1)) by Th19
      .= new_bi_fun2(ConsecutiveDelta2(q,O1),Quadr2(q,O1)) by LATTICE5:def 15;
    hence
    ConsecutiveDelta2(q,succ O1).(x,z) <= ConsecutiveDelta2(q,succ O1).(x
    ,y) "\/" ConsecutiveDelta2(q,succ O1).(y,z) by A17;
  end;
A18: for O1 st O1 <> 0 & O1 is limit_ordinal & for O2 st O2 in O1 holds X[
  O2] holds X[O1]
  proof
    deffunc U(Ordinal) = ConsecutiveDelta2(q,$1);
    let O2 be Ordinal;
    assume that
A19: O2 <> 0 & O2 is limit_ordinal and
A20: for O1 be Ordinal st O1 in O2 holds (O1 c= DistEsti(d) implies
    ConsecutiveDelta2(q,O1) is u.t.i.) and
A21: O2 c= DistEsti(d);
    set CS = ConsecutiveSet2(A,O2);
    consider Ls being Sequence such that
A22: dom Ls = O2 & for O1 being Ordinal st O1 in O2 holds Ls.O1 = U(O1
    ) from ORDINAL2:sch 2;
    ConsecutiveDelta2(q,O2) = union rng Ls by A19,A22,Th20;
    then reconsider f = union rng Ls as BiFunction of CS,L;
    deffunc U(Ordinal) = ConsecutiveSet2(A,$1);
    consider Ts being Sequence such that
A23: dom Ts = O2 & for O1 being Ordinal st O1 in O2 holds Ts.O1 = U(O1
    ) from ORDINAL2:sch 2;
A24: ConsecutiveSet2(A,O2) = union rng Ts by A19,A23,Th16;
    f is u.t.i.
    proof
      let x,y,z be Element of CS;
      consider X being set such that
A25:  x in X and
A26:  X in rng Ts by A24,TARSKI:def 4;
      consider o1 being object such that
A27:  o1 in dom Ts and
A28:  X = Ts.o1 by A26,FUNCT_1:def 3;
      consider Y being set such that
A29:  y in Y and
A30:  Y in rng Ts by A24,TARSKI:def 4;
      consider o2 being object such that
A31:  o2 in dom Ts and
A32:  Y = Ts.o2 by A30,FUNCT_1:def 3;
      consider Z being set such that
A33:  z in Z and
A34:  Z in rng Ts by A24,TARSKI:def 4;
      consider o3 being object such that
A35:  o3 in dom Ts and
A36:  Z = Ts.o3 by A34,FUNCT_1:def 3;
      reconsider o1,o2,o3 as Ordinal by A27,A31,A35;
A37:  x in ConsecutiveSet2(A,o1) by A23,A25,A27,A28;
A38:  Ls.o3 = ConsecutiveDelta2(q,o3) by A22,A23,A35;
      then reconsider h3 = Ls.o3 as BiFunction of ConsecutiveSet2(A,o3),L;
A39:  h3 is u.t.i.
      proof
        let x,y,z be Element of ConsecutiveSet2(A,o3);
        o3 c= DistEsti(d) by A21,A23,A35,ORDINAL1:def 2;
        then
A40:    ConsecutiveDelta2(q,o3) is u.t.i. by A20,A23,A35;
        ConsecutiveDelta2(q,o3) = h3 by A22,A23,A35;
        hence h3.(x,z) <= h3.(x,y) "\/" h3.(y,z) by A40;
      end;
A41:  dom h3 = [:ConsecutiveSet2(A,o3),ConsecutiveSet2(A,o3):] by FUNCT_2:def 1
;
A42:  z in ConsecutiveSet2(A,o3) by A23,A33,A35,A36;
A43:  Ls.o2 = ConsecutiveDelta2(q,o2) by A22,A23,A31;
      then reconsider h2 = Ls.o2 as BiFunction of ConsecutiveSet2(A,o2),L;
A44:  h2 is u.t.i.
      proof
        let x,y,z be Element of ConsecutiveSet2(A,o2);
        o2 c= DistEsti(d) by A21,A23,A31,ORDINAL1:def 2;
        then
A45:    ConsecutiveDelta2(q,o2) is u.t.i. by A20,A23,A31;
        ConsecutiveDelta2(q,o2) = h2 by A22,A23,A31;
        hence h2.(x,z) <= h2.(x,y) "\/" h2.(y,z) by A45;
      end;
A46:  dom h2 = [:ConsecutiveSet2(A,o2),ConsecutiveSet2(A,o2):] by FUNCT_2:def 1
;
A47:  Ls.o1 = ConsecutiveDelta2(q,o1) by A22,A23,A27;
      then reconsider h1 = Ls.o1 as BiFunction of ConsecutiveSet2(A,o1),L;
A48:  h1 is u.t.i.
      proof
        let x,y,z be Element of ConsecutiveSet2(A,o1);
        o1 c= DistEsti(d) by A21,A23,A27,ORDINAL1:def 2;
        then
A49:    ConsecutiveDelta2(q,o1) is u.t.i. by A20,A23,A27;
        ConsecutiveDelta2(q,o1) = h1 by A22,A23,A27;
        hence h1.(x,z) <= h1.(x,y) "\/" h1.(y,z) by A49;
      end;
A50:  dom h1 = [:ConsecutiveSet2(A,o1),ConsecutiveSet2(A,o1):] by FUNCT_2:def 1
;
A51:  y in ConsecutiveSet2(A,o2) by A23,A29,A31,A32;
      per cases;
      suppose
A52:    o1 c= o3;
        then
A53:    ConsecutiveSet2(A,o1) c= ConsecutiveSet2(A,o3) by Th21;
        thus f.(x,y) "\/" f.(y,z) >= f.(x,z)
        proof
          per cases;
          suppose
A54:        o2 c= o3;
            reconsider z9 = z as Element of ConsecutiveSet2(A,o3) by A23,A33
,A35,A36;
            reconsider x9 = x as Element of ConsecutiveSet2(A,o3) by A37,A53;
            ConsecutiveDelta2(q,o3) in rng Ls by A22,A23,A35,A38,FUNCT_1:def 3;
            then
A55:        h3 c= f by A38,ZFMISC_1:74;
A56:        ConsecutiveSet2(A,o2) c= ConsecutiveSet2(A,o3) by A54,Th21;
            then reconsider y9 = y as Element of ConsecutiveSet2(A,o3) by A51;
            [y,z] in dom h3 by A51,A42,A41,A56,ZFMISC_1:87;
            then
A57:        f.(y,z) = h3.(y9,z9) by A55,GRFUNC_1:2;
            [x,z] in dom h3 by A37,A42,A41,A53,ZFMISC_1:87;
            then
A58:        f.(x,z) = h3.(x9,z9) by A55,GRFUNC_1:2;
            [x,y] in dom h3 by A37,A51,A41,A53,A56,ZFMISC_1:87;
            then f.(x,y) = h3.(x9,y9) by A55,GRFUNC_1:2;
            hence thesis by A39,A57,A58;
          end;
          suppose
A59:        o3 c= o2;
            reconsider y9 = y as Element of ConsecutiveSet2(A,o2) by A23,A29
,A31,A32;
            ConsecutiveDelta2(q,o2) in rng Ls by A22,A23,A31,A43,FUNCT_1:def 3;
            then
A60:        h2 c= f by A43,ZFMISC_1:74;
A61:        ConsecutiveSet2(A,o3) c= ConsecutiveSet2(A,o2) by A59,Th21;
            then reconsider z9 = z as Element of ConsecutiveSet2(A,o2) by A42;
            [y,z] in dom h2 by A51,A42,A46,A61,ZFMISC_1:87;
            then
A62:        f.(y,z) = h2.(y9,z9) by A60,GRFUNC_1:2;
            ConsecutiveSet2(A,o1) c= ConsecutiveSet2(A,o3) by A52,Th21;
            then
A63:        ConsecutiveSet2(A,o1) c= ConsecutiveSet2(A,o2) by A61;
            then reconsider x9 = x as Element of ConsecutiveSet2(A,o2) by A37;
            [x,y] in dom h2 by A37,A51,A46,A63,ZFMISC_1:87;
            then
A64:        f.(x,y) = h2.(x9,y9) by A60,GRFUNC_1:2;
            [x,z] in dom h2 by A37,A42,A46,A61,A63,ZFMISC_1:87;
            then f.(x,z) = h2.(x9,z9) by A60,GRFUNC_1:2;
            hence thesis by A44,A64,A62;
          end;
        end;
      end;
      suppose
A65:    o3 c= o1;
        then
A66:    ConsecutiveSet2(A,o3) c= ConsecutiveSet2(A,o1) by Th21;
        thus f.(x,y) "\/" f.(y,z) >= f.(x,z)
        proof
          per cases;
          suppose
A67:        o1 c= o2;
            reconsider y9 = y as Element of ConsecutiveSet2(A,o2) by A23,A29
,A31,A32;
            ConsecutiveDelta2(q,o2) in rng Ls by A22,A23,A31,A43,FUNCT_1:def 3;
            then
A68:        h2 c= f by A43,ZFMISC_1:74;
A69:        ConsecutiveSet2(A,o1) c= ConsecutiveSet2(A,o2) by A67,Th21;
            then reconsider x9 = x as Element of ConsecutiveSet2(A,o2) by A37;
            [x,y] in dom h2 by A37,A51,A46,A69,ZFMISC_1:87;
            then
A70:        f.(x,y) = h2.(x9,y9) by A68,GRFUNC_1:2;
            ConsecutiveSet2(A,o3) c= ConsecutiveSet2(A,o1) by A65,Th21;
            then
A71:        ConsecutiveSet2(A,o3) c= ConsecutiveSet2(A,o2) by A69;
            then reconsider z9 = z as Element of ConsecutiveSet2(A,o2) by A42;
            [y,z] in dom h2 by A51,A42,A46,A71,ZFMISC_1:87;
            then
A72:        f.(y,z) = h2.(y9,z9) by A68,GRFUNC_1:2;
            [x,z] in dom h2 by A37,A42,A46,A69,A71,ZFMISC_1:87;
            then f.(x,z) = h2.(x9,z9) by A68,GRFUNC_1:2;
            hence thesis by A44,A70,A72;
          end;
          suppose
A73:        o2 c= o1;
            reconsider x9 = x as Element of ConsecutiveSet2(A,o1) by A23,A25
,A27,A28;
            reconsider z9 = z as Element of ConsecutiveSet2(A,o1) by A42,A66;
            ConsecutiveDelta2(q,o1) in rng Ls by A22,A23,A27,A47,FUNCT_1:def 3;
            then
A74:        h1 c= f by A47,ZFMISC_1:74;
A75:        ConsecutiveSet2(A,o2) c= ConsecutiveSet2(A,o1) by A73,Th21;
            then reconsider y9 = y as Element of ConsecutiveSet2(A,o1) by A51;
            [x,y] in dom h1 by A37,A51,A50,A75,ZFMISC_1:87;
            then
A76:        f.(x,y) = h1.(x9,y9) by A74,GRFUNC_1:2;
            [x,z] in dom h1 by A37,A42,A50,A66,ZFMISC_1:87;
            then
A77:        f.(x,z) = h1.(x9,z9) by A74,GRFUNC_1:2;
            [y,z] in dom h1 by A51,A42,A50,A66,A75,ZFMISC_1:87;
            then f.(y,z) = h1.(y9,z9) by A74,GRFUNC_1:2;
            hence thesis by A48,A76,A77;
          end;
        end;
      end;
    end;
    hence thesis by A19,A22,Th20;
  end;
A78: X[0]
  proof
    assume 0 c= DistEsti(d);
    let x,y,z be Element of ConsecutiveSet2(A,0);
    reconsider x9 = x, y9 = y, z9 = z as Element of A by Th14;
    ConsecutiveDelta2(q,0) = d & d.(x9,z9) <= d.(x9,y9) "\/" d.(y9,z9) by A3
,Th18;
    hence ConsecutiveDelta2(q,0).(x,z) <= ConsecutiveDelta2(q,0).(x,y) "\/"
    ConsecutiveDelta2(q,0).(y,z);
  end;
  for O being Ordinal holds X[O] from ORDINAL2:sch 1(A78,A4,A18);
  hence thesis;
end;

theorem
  for A being non empty set for L being lower-bounded modular LATTICE
  for d being distance_function of A,L for O being Ordinal for q being QuadrSeq
  of d st O c= DistEsti(d) holds ConsecutiveDelta2(q,O) is distance_function of
  ConsecutiveSet2(A,O),L by Th25,Th26,Th27;

definition
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  func NextSet2(d) -> set equals
  ConsecutiveSet2(A,DistEsti(d));
  correctness;
end;

registration
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  cluster NextSet2(d) -> non empty;
  coherence;
end;

definition
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be BiFunction of A,L;
  let q be QuadrSeq of d;
  func NextDelta2(q) -> set equals
  ConsecutiveDelta2(q,DistEsti(d));
  correctness;
end;

definition
  let A be non empty set;
  let L be lower-bounded modular LATTICE;
  let d be distance_function of A,L;
  let q be QuadrSeq of d;
  redefine func NextDelta2(q) -> distance_function of NextSet2(d),L;  :: redefines NextDelta2 (LATTICE8, definition)
  coherence by Th25,Th26,Th27;
end;

definition
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be distance_function of A,L;
  let Aq be non empty set;
  let dq be distance_function of Aq,L;
  pred Aq, dq is_extension2_of A,d means

  ex q being QuadrSeq of d st Aq = NextSet2(d) & dq = NextDelta2(q);
end;

theorem Th29:
  for A being non empty set for L be lower-bounded LATTICE for d
be distance_function of A,L for Aq be non empty set for dq be distance_function
  of Aq,L st Aq, dq is_extension2_of A,d for x,y being Element of A, a,b being
Element of L st d.(x,y) <= a "\/" b ex z1,z2 being Element of Aq st dq.(x,z1) =
  a & dq.(z1,z2) = (d.(x,y) "\/" a) "/\" b & dq.(z2,y) = a
proof
  let A be non empty set;
  let L be lower-bounded LATTICE;
  let d be distance_function of A,L;
  let Aq be non empty set;
  let dq be distance_function of Aq,L;
  assume Aq, dq is_extension2_of A,d;
  then consider q being QuadrSeq of d such that
A1: Aq = NextSet2(d) and
A2: dq = NextDelta2(q);
  let x,y be Element of A;
  let a,b be Element of L;
A3: rng q = {[x9,y9,a9,b9] where x9 is Element of A, y9 is Element of A, a9
is Element of L, b9 is Element of L: d.(x9,y9) <= a9"\/"b9} by LATTICE5:def 13;
  assume d.(x,y) <= a "\/" b;
  then [x,y,a,b] in rng q by A3;
  then consider o being object such that
A4: o in dom q and
A5: q.o = [x,y,a,b] by FUNCT_1:def 3;
  reconsider o as Ordinal by A4;
A6: q.o = Quadr2(q,o) by A4,Def6;
  then
A7: x = Quadr2(q,o)`1_4 by A5;
A8: b = Quadr2(q,o)`4_4 by A5,A6;
A9: y = Quadr2(q,o)`2_4 by A5,A6;
  reconsider B = ConsecutiveSet2(A,o) as non empty set;
  {B} in {{B}, {{B}} } by TARSKI:def 2;
  then
A10: {B} in B \/ {{B}, {{B}} } by XBOOLE_0:def 3;
  o in DistEsti(d) by A4,LATTICE5:25;
  then
A11: succ o c= DistEsti(d) by ORDINAL1:21;
  then
A12: ConsecutiveDelta2(q,succ o) c= ConsecutiveDelta2(q,DistEsti(d)) by Th24;
  reconsider cd = ConsecutiveDelta2(q,o) as BiFunction of B,L;
  reconsider Q = Quadr2(q,o) as Element of [:B,B,the carrier of L,the carrier
  of L:];
A13: {{B}} in {{B}, {{B}} } by TARSKI:def 2;
  then
A14: {{B}} in new_set2 B by XBOOLE_0:def 3;
  ConsecutiveSet2(A,succ o) = new_set2 B by Th15;
  then new_set2 B c= ConsecutiveSet2(A,DistEsti(d)) by A11,Th21;
  then reconsider z1={B},z2={{B}} as Element of Aq by A1,A10,A14;
  take z1,z2;
A15: cd is zeroed by Th25;
  A c= B by Th17;
  then reconsider xo = x, yo = y as Element of B;
A16: B c= new_set2 B by XBOOLE_1:7;
  reconsider x1 = xo, y1 = yo as Element of new_set2 B by A16;
A17: ConsecutiveDelta2(q,succ o) = new_bi_fun2(BiFun(ConsecutiveDelta2(q,o),
  ConsecutiveSet2(A,o),L),Quadr2(q,o)) by Th19
    .= new_bi_fun2(cd,Q) by LATTICE5:def 15;
  dom d = [:A,A:] by FUNCT_2:def 1;
  then
A18: [xo,yo] in dom d by ZFMISC_1:87;
  d c= cd by Th23;
  then
A19: cd.(xo,yo) = d.(x,y) by A18,GRFUNC_1:2;
A20: a = Quadr2(q,o)`3_4 by A5,A6;
A21: dom new_bi_fun2(cd,Q) = [:new_set2 B,new_set2 B:] by FUNCT_2:def 1;
  then [x1,{B}] in dom new_bi_fun2(cd,Q) by A10,ZFMISC_1:87;
  hence dq.(x,z1) = new_bi_fun2(cd,Q).(x1,{B}) by A2,A12,A17,GRFUNC_1:2
    .= cd.(xo,xo)"\/"a by A7,A20,Def4
    .= Bottom L"\/"a by A15
    .= a by WAYBEL_1:3;
  [{B},{{B}}] in dom new_bi_fun2(cd,Q) by A10,A14,A21,ZFMISC_1:87;
  hence dq.(z1,z2) = new_bi_fun2(cd,Q).({B},{{B}}) by A2,A12,A17,GRFUNC_1:2
    .= (d.(x,y)"\/"a)"/\"b by A7,A9,A20,A8,A19,Def4;
  {{B}} in B \/ {{B}, {{B}} } by A13,XBOOLE_0:def 3;
  then [{{B}},y1] in dom new_bi_fun2(cd,Q) by A21,ZFMISC_1:87;
  hence dq.(z2,y) = new_bi_fun2(cd,Q).({{B}},y1) by A2,A12,A17,GRFUNC_1:2
    .= cd.(yo,yo)"\/"a by A9,A20,Def4
    .= Bottom L"\/"a by A15
    .= a by WAYBEL_1:3;
end;

definition
  let A be non empty set;
  let L be lower-bounded modular LATTICE;
  let d be distance_function of A,L;
  mode ExtensionSeq2 of A,d -> Function means
    :Def11:
    dom it = NAT & it.0 = [A
    ,d] & for n being Nat holds ex A9 being non empty set, d9 being
distance_function of A9,L, Aq being non empty set, dq being distance_function
of Aq,L st Aq, dq is_extension2_of A9,d9 & it.n = [A9,d9] & it.(n+1) = [Aq,dq];
  existence
  proof
    defpred P[set,set,set] means (ex A9 being non empty set, d9 being
distance_function of A9,L, Aq being non empty set, dq being distance_function
of Aq,L st Aq, dq is_extension2_of A9,d9 & $2 = [A9,d9] & $3 = [Aq,dq]) or $3=
0 & not ex A9 being non empty set, d9 being distance_function of A9,L, Aq being
non empty set, dq being distance_function of Aq,L st Aq, dq is_extension2_of A9
    ,d9 & $2 = [A9,d9];
A1: for n being Nat for x being set ex y being set st P[n,x,y]
    proof
      let n be Nat;
      let x be set;
      per cases;
      suppose
        ex A9 being non empty set, d9 being distance_function of A9,L,
        Aq being non empty set, dq being distance_function of Aq,L st Aq, dq
        is_extension2_of A9,d9 & x = [A9,d9];
        then consider
        A9 being non empty set, d9 being distance_function of A9,L,
        Aq being non empty set, dq being distance_function of Aq,L such that
A2:     Aq, dq is_extension2_of A9,d9 & x = [A9,d9];
        take [Aq,dq];
        thus thesis by A2;
      end;
      suppose
A3:     not ex A9 being non empty set, d9 being distance_function of
A9,L, Aq being non empty set, dq being distance_function of Aq,L st Aq, dq
        is_extension2_of A9,d9 & x = [A9,d9];
        take 0;
        thus thesis by A3;
      end;
    end;
    consider f being Function such that
A4: dom f = NAT and
A5: f.0 = [A,d] and
A6: for n being Nat holds P[n,f.n,f.(n+1)] from RECDEF_1:
    sch 1( A1);
    take f;
    thus dom f = NAT by A4;
    thus f.0 = [A,d] by A5;
    defpred X[Nat] means ex A9 being non empty set, d9 being
distance_function of A9,L, Aq being non empty set, dq being distance_function
of Aq,L st Aq, dq is_extension2_of A9,d9 & f.$1 = [A9,d9] & f.($1+1) = [Aq,dq];
A7: for k being Nat st X[k] holds X[k+1]
    proof
      let k be Nat;
      given A9 being non empty set, d9 being distance_function of A9,L, Aq
      being non empty set, dq being distance_function of Aq,L such that
      Aq, dq is_extension2_of A9,d9 and
      f.k = [A9,d9] and
A8:   f.(k+1) = [Aq,dq];
      ex A1 being non empty set, d1 being distance_function of A1,L, AQ
      being non empty set, DQ being distance_function of AQ,L st AQ, DQ
      is_extension2_of A1,d1 & f.(k+1) = [A1,d1]
      proof
        set Q = the QuadrSeq of dq;
        set AQ = NextSet2(dq);
        take Aq,dq;
        set DQ = NextDelta2(Q);
        take AQ,DQ;
        thus AQ, DQ is_extension2_of Aq,dq;
        thus thesis by A8;
      end;
      hence thesis by A6;
    end;
    ex A9 being non empty set, d9 being distance_function of A9,L, Aq
    being non empty set, dq being distance_function of Aq,L st Aq, dq
    is_extension2_of A9,d9 & f.0 = [A9,d9]
    proof
      set Aq = NextSet2(d);
      set q = the QuadrSeq of d;
      take A,d;
      consider dq being distance_function of Aq,L such that
A9:   dq = NextDelta2(q);
      take Aq,dq;
      thus Aq, dq is_extension2_of A,d by A9;
      thus thesis by A5;
    end;
    then
A10: X[0] by A6;
    thus for k being Nat holds X[k] from NAT_1:sch 2(A10, A7);
  end;
end;

theorem Th30:
  for A being non empty set for L be lower-bounded modular LATTICE
  for d be distance_function of A,L for S being ExtensionSeq2 of A,d for k,l
  being Nat st k <= l holds (S.k)`1 c= (S.l)`1
proof
  let A be non empty set;
  let L be lower-bounded modular LATTICE;
  let d be distance_function of A,L;
  let S be ExtensionSeq2 of A,d;
  let k be Nat;
  defpred X[Nat] means k <= $1 implies (S.k)`1 c= (S.$1)`1;
A1: for i being Nat st X[i] holds X[i+1]
  proof
    let i be Nat;
    assume that
A2: k <= i implies (S.k)`1 c= (S.i)`1 and
A3: k <= i+1;
    per cases by A3,NAT_1:8;
    suppose
      k = i+1;
      hence thesis;
    end;
    suppose
A4:   k <= i;
      consider A9 being non empty set, d9 being distance_function of A9,L, Aq
      being non empty set, dq being distance_function of Aq,L such that
A5:   Aq, dq is_extension2_of A9,d9 and
A6:   S.i = [A9,d9] and
A7:   S.(i+1) = [Aq,dq] by Def11;
A8:   (S.i)`1 c= ConsecutiveSet2(A9,DistEsti(d9)) by Th17,A6;
      ex q being QuadrSeq of d9 st Aq = NextSet2(d9) & dq = NextDelta2(q)
      by A5;
      then [Aq,dq]`1 = ConsecutiveSet2(A9,DistEsti(d9));
      hence thesis by A2,A4,A8,A7;
    end;
  end;
A9: X[0] by NAT_1:3;
  thus for l being Nat holds X[l] from NAT_1:sch 2(A9, A1);
end;

theorem Th31:
  for A being non empty set for L be lower-bounded modular LATTICE
  for d be distance_function of A,L for S being ExtensionSeq2 of A,d for k,l
  being Nat st k <= l holds (S.k)`2 c= (S.l)`2
proof
  let A be non empty set;
  let L be lower-bounded modular LATTICE;
  let d be distance_function of A,L;
  let S be ExtensionSeq2 of A,d;
  let k be Nat;
  defpred X[Nat] means k <= $1 implies (S.k)`2 c= (S.$1)`2;
A1: for i being Nat st X[i] holds X[i+1]
  proof
    let i be Nat;
    assume that
A2: k <= i implies (S.k)`2 c= (S.i)`2 and
A3: k <= i+1;
    per cases by A3,NAT_1:8;
    suppose
      k = i+1;
      hence thesis;
    end;
    suppose
A4:   k <= i;
      consider A9 being non empty set, d9 being distance_function of A9,L, Aq
      being non empty set, dq being distance_function of Aq,L such that
A5:   Aq, dq is_extension2_of A9,d9 and
A6:   S.i = [A9,d9] and
A7:   S.(i+1) = [Aq,dq] by Def11;
      consider q being QuadrSeq of d9 such that
      Aq = NextSet2(d9) and
A8:   dq = NextDelta2(q) by A5;
A9:   (S.i)`2 c= ConsecutiveDelta2(q,DistEsti(d9)) by Th23,A6;
      [Aq,dq]`2 = ConsecutiveDelta2(q,DistEsti(d9)) by A8;
      hence thesis by A2,A4,A9,A7;
    end;
  end;
A10: X[0] by NAT_1:3;
  thus for l being Nat holds X[l] from NAT_1:sch 2(A10, A1);
end;

theorem Th32:
  for L be lower-bounded modular LATTICE for S being ExtensionSeq2
of the carrier of L, BasicDF(L) for FS being non empty set st FS = union the
set of all  (S.i
)`1 where i is Element of NAT holds union the set of all  (S.i)`2 where i
  is Element of NAT is distance_function of FS,L
proof
  let L be lower-bounded modular LATTICE;
  let S be ExtensionSeq2 of the carrier of L, BasicDF(L);
  let FS be non empty set;
  assume
A1: FS = union the set of all  (S.i)`1 where i is Element of NAT;
  reconsider FS as non empty set;
  set A = the carrier of L;
  set FD = union the set of all  (S.i)`2 where i is Element of NAT;
  now
    let x,y be set;
    assume that
A2: x in the set of all  (S.i)`2 where i is Element of NAT and
A3: y in the set of all  (S.i)`2 where i is Element of NAT;
    consider k being Element of NAT such that
A4: x = (S.k)`2 by A2;
    consider l being Element of NAT such that
A5: y = (S.l)`2 by A3;
    k <= l or l <= k;
    then x c= y or y c= x by A4,A5,Th31;
    hence x,y are_c=-comparable;
  end;
  then
A6: the set of all  (S.i)`2 where i is Element of NAT is c=-linear;
  the set of all  (S.i)`2 where i is Element of NAT c= PFuncs([:FS,
  FS:],A)
  proof
    let z be object;
    assume z in the set of all  (S.i)`2 where i is Element of NAT;
    then consider j being Element of NAT such that
A7: z = (S.j)`2;
    consider A9 being non empty set, d9 being distance_function of A9,L, Aq
    being non empty set, dq being distance_function of Aq,L such that
    Aq, dq is_extension2_of A9,d9 and
A8: S.j = [A9,d9] and
    S.(j+1) = [Aq,dq] by Def11;
A9:  A9 = [A9,d9]`1;
    A9 in the set of all  (S.i)`1 where i is Element of NAT
       by A9,A8;
    then dom d9 = [:A9,A9:] & A9 c= FS by A1,FUNCT_2:def 1,ZFMISC_1:74;
    then
A10: rng d9 c= A & dom d9 c= [:FS,FS:] by ZFMISC_1:96;
    z = d9 by A7,A8;
    hence thesis by A10,PARTFUN1:def 3;
  end;
  then FD in PFuncs([:FS,FS:],A) by A6,TREES_2:40;
  then
A11: ex g being Function st FD = g & dom g c= [:FS,FS:] & rng g c= A by
PARTFUN1:def 3;
  (S.0)`1 in the set of all  (S.i)`1 where i is Element of NAT;
  then reconsider
  X = the set of all  (S.i)`1 where i is Element of NAT as
  non empty set;
  set LL = { [:I,I:] where I is Element of X : I in X }, PP = the set of all
 [:(S.i)`1,(S.i
  )`1:] where i is Element of NAT;
  defpred X[object,object] means $2 = (S.$1)`2;
A12: LL = PP
  proof
    thus LL c= PP
    proof
      let x be object;
      assume x in LL;
      then consider J being Element of X such that
A13:  x = [:J,J:] and
A14:  J in X;
      ex j being Element of NAT st J = (S.j)`1 by A14;
      hence thesis by A13;
    end;
    let x be object;
    assume x in PP;
    then consider j being Element of NAT such that
A15: x = [:(S.j)`1,(S.j)`1:];
    (S.j)`1 in X;
    hence thesis by A15;
  end;
  reconsider FD as Function by A11;
A16: for x being object st x in NAT ex y being object st X[x,y];
  consider F being Function such that
A17: dom F = NAT and
A18: for x being object st x in NAT holds X[x,F.x] from CLASSES1:sch 1(A16);
A19: rng F = the set of all  (S.i)`2 where i is Element of NAT
  proof
    thus rng F c= the set of all  (S.i)`2 where i is Element of NAT
    proof
      let x be object;
      assume x in rng F;
      then consider j being object such that
A20:  j in dom F and
A21:  F.j = x by FUNCT_1:def 3;
      reconsider j as Element of NAT by A17,A20;
      x = (S.j)`2 by A18,A21;
      hence thesis;
    end;
    let x be object;
    assume x in the set of all  (S.i)`2 where i is Element of NAT;
    then consider j being Element of NAT such that
A22: x = (S.j)`2;
    x = F.j by A18,A22;
    hence thesis by A17,FUNCT_1:def 3;
  end;
  F is Function-yielding
  proof
    let x be object;
    assume x in dom F;
    then reconsider j = x as Element of NAT by A17;
    consider A1 being non empty set, d1 being distance_function of A1,L, Aq1
    being non empty set, dq1 being distance_function of Aq1,L such that
    Aq1, dq1 is_extension2_of A1,d1 and
A23: S.j = [A1,d1] and
    S.(j+1) = [Aq1,dq1] by Def11;
    [A1,d1]`2 = d1;
    hence thesis by A18,A23;
  end;
  then reconsider F as Function-yielding Function;
A24: rng doms F = PP
  proof
    thus rng doms F c= PP
    proof
      let x be object;
      assume x in rng doms F;
      then consider j being object such that
A25:  j in dom doms F and
A26:  x = (doms F).j by FUNCT_1:def 3;
A27:  j in dom F by A25,FUNCT_6:59;
      reconsider j as Element of NAT by A17,A25,FUNCT_6:59;
      consider A1 being non empty set, d1 being distance_function of A1,L, Aq1
      being non empty set, dq1 being distance_function of Aq1,L such that
      Aq1, dq1 is_extension2_of A1,d1 and
A28:  S.j = [A1,d1] and
      S.(j+1) = [Aq1,dq1] by Def11;
A29:  [A1,d1]`2 = d1;
      x = dom (F.j) by A26,A27,FUNCT_6:22
        .= dom d1 by A18,A29,A28
        .= [:(S.j)`1,(S.j)`1:] by A28,FUNCT_2:def 1;
      hence thesis;
    end;
    let x be object;
    assume x in PP;
    then consider j being Element of NAT such that
A30: x = [:(S.j)`1,(S.j)`1:];
    consider A1 being non empty set, d1 being distance_function of A1,L, Aq1
    being non empty set, dq1 being distance_function of Aq1,L such that
    Aq1, dq1 is_extension2_of A1,d1 and
A31: S.j = [A1,d1] and
    S.(j+1) = [Aq1,dq1] by Def11;
A32: [A1,d1]`2 = d1;
    j in NAT;
    then
A33: j in dom doms F by A17,FUNCT_6:59;
    x = dom d1 by A30,A31,FUNCT_2:def 1
      .= dom (F.j) by A18,A32,A31
      .= (doms F).j by A17,FUNCT_6:22;
    hence thesis by A33,FUNCT_1:def 3;
  end;
  now
    let x,y be set;
    assume that
A34: x in X and
A35: y in X;
    consider k being Element of NAT such that
A36: x = (S.k)`1 by A34;
    consider l being Element of NAT such that
A37: y = (S.l)`1 by A35;
    k <= l or l <= k;
    then x c= y or y c= x by A36,A37,Th30;
    hence x,y are_c=-comparable;
  end;
  then X is c=-linear;
  then [:FS,FS:] = union rng doms F by A1,A24,A12,LATTICE5:3
    .= dom FD by A19,LATTICE5:1;
  then reconsider FD as BiFunction of FS,L by A11,FUNCT_2:def 1,RELSET_1:4;
A38: FD is symmetric
  proof
    let x,y be Element of FS;
    consider x1 being set such that
A39: x in x1 and
A40: x1 in X by A1,TARSKI:def 4;
    consider k being Element of NAT such that
A41: x1 = (S.k)`1 by A40;
    consider A1 being non empty set, d1 being distance_function of A1,L, Aq1
    being non empty set, dq1 being distance_function of Aq1,L such that
    Aq1, dq1 is_extension2_of A1,d1 and
A42: S.k = [A1,d1] and
    S.(k+1) = [Aq1,dq1] by Def11;
A43: [A1,d1]`1 = A1;
A44: x in A1 by A39,A41,A42;
 [A1,d1]`2 = d1;
    then d1 in the set of all  (S.i)`2 where i is Element of NAT by A42;
    then
A45: d1 c= FD by ZFMISC_1:74;
    consider y1 being set such that
A46: y in y1 and
A47: y1 in X by A1,TARSKI:def 4;
    consider l being Element of NAT such that
A48: y1 = (S.l)`1 by A47;
    consider A2 being non empty set, d2 being distance_function of A2,L, Aq2
    being non empty set, dq2 being distance_function of Aq2,L such that
    Aq2, dq2 is_extension2_of A2,d2 and
A49: S.l = [A2,d2] and
    S.(l+1) = [Aq2,dq2] by Def11;
A50: [A2,d2]`1 = A2;
A51: y in A2 by A46,A48,A49;
 [A2,d2]`2 = d2;
    then d2 in the set of all  (S.i)`2 where i is Element of NAT by A49;
    then
A52: d2 c= FD by ZFMISC_1:74;
    per cases;
    suppose
      k <= l;
      then A1 c= A2 by A43,A50,Th30,A42,A49;
      then reconsider x9=x,y9=y as Element of A2 by A44,A46,A48,A49;
A53:  dom d2 = [:A2,A2:] by FUNCT_2:def 1;
      hence FD.(x,y) = d2.[x9,y9] by A52,GRFUNC_1:2
        .= d2.(x9,y9)
        .= d2.(y9,x9) by LATTICE5:def 5
        .= FD.[y9,x9] by A52,A53,GRFUNC_1:2
        .= FD.(y,x);
    end;
    suppose
      l <= k;
      then A2 c= A1 by A43,A50,Th30,A42,A49;
      then reconsider x9=x,y9=y as Element of A1
           by A39,A41,A42,A51;
A54:  dom d1 = [:A1,A1:] by FUNCT_2:def 1;
      hence FD.(x,y) = d1.[x9,y9] by A45,GRFUNC_1:2
        .= d1.(x9,y9)
        .= d1.(y9,x9) by LATTICE5:def 5
        .= FD.[y9,x9] by A45,A54,GRFUNC_1:2
        .= FD.(y,x);
    end;
  end;
A55: FD is u.t.i.
  proof
    let x,y,z be Element of FS;
    consider x1 being set such that
A56: x in x1 and
A57: x1 in X by A1,TARSKI:def 4;
    consider k being Element of NAT such that
A58: x1 = (S.k)`1 by A57;
    consider A1 being non empty set, d1 being distance_function of A1,L, Aq1
    being non empty set, dq1 being distance_function of Aq1,L such that
    Aq1, dq1 is_extension2_of A1,d1 and
A59: S.k = [A1,d1] and
    S.(k+1) = [Aq1,dq1] by Def11;
A60: [A1,d1]`1 = A1;
A61: x in A1 by A56,A58,A59;
  [A1,d1]`2 = d1;
    then d1 in the set of all  (S.i)`2 where i is Element of NAT by A59;
    then
A62: d1 c= FD by ZFMISC_1:74;
A63: dom d1 = [:A1,A1:] by FUNCT_2:def 1;
    consider y1 being set such that
A64: y in y1 and
A65: y1 in X by A1,TARSKI:def 4;
    consider l being Element of NAT such that
A66: y1 = (S.l)`1 by A65;
    consider A2 being non empty set, d2 being distance_function of A2,L, Aq2
    being non empty set, dq2 being distance_function of Aq2,L such that
    Aq2, dq2 is_extension2_of A2,d2 and
A67: S.l = [A2,d2] and
    S.(l+1) = [Aq2,dq2] by Def11;
A68: [A2,d2]`1 = A2;
A69: y in A2 by A64,A66,A67;
  [A2,d2]`2 = d2;
    then d2 in the set of all  (S.i)`2 where i is Element of NAT by A67;
    then
A70: d2 c= FD by ZFMISC_1:74;
A71: dom d2 = [:A2,A2:] by FUNCT_2:def 1;
    consider z1 being set such that
A72: z in z1 and
A73: z1 in X by A1,TARSKI:def 4;
    consider n being Element of NAT such that
A74: z1 = (S.n)`1 by A73;
    consider A3 being non empty set, d3 being distance_function of A3,L, Aq3
    being non empty set, dq3 being distance_function of Aq3,L such that
    Aq3, dq3 is_extension2_of A3,d3 and
A75: S.n = [A3,d3] and
    S.(n+1) = [Aq3,dq3] by Def11;
A76: [A3,d3]`1 = A3;
A77: z in A3 by A72,A74,A75;
  [A3,d3]`2 = d3;
    then d3 in the set of all  (S.i)`2 where i is Element of NAT by A75;
    then
A78: d3 c= FD by ZFMISC_1:74;
A79: dom d3 = [:A3,A3:] by FUNCT_2:def 1;
    per cases;
    suppose
      k <= l;
      then
A80:  A1 c= A2 by A60,A68,Th30,A59,A67;
      thus FD.(x,y) "\/" FD.(y,z) >= FD.(x,z)
      proof
        per cases;
        suppose
          l <= n;
          then
A81:      A2 c= A3 by A68,A76,Th30,A67,A75;
          then A1 c= A3 by A80;
          then reconsider
          x9 = x, y9 = y, z9 = z as Element of A3
      by A61,A69,A72,A74,A75,A81;
A82:      FD.(y,z) = d3.[y9,z9] by A78,A79,GRFUNC_1:2
            .= d3.(y9,z9);
A83:      FD.(x,z) = d3.[x9,z9] by A78,A79,GRFUNC_1:2
            .= d3.(x9,z9);
          FD.(x,y) = d3.[x9,y9] by A78,A79,GRFUNC_1:2
            .= d3.(x9,y9);
          hence thesis by A82,A83,LATTICE5:def 7;
        end;
        suppose
          n <= l;
          then A3 c= A2 by A68,A76,Th30,A67,A75;
          then reconsider
          x9 = x, y9 = y, z9 = z as Element of A2
       by A61,A64,A66,A67,A77,A80;
A84:      FD.(y,z) = d2.[y9,z9] by A70,A71,GRFUNC_1:2
            .= d2.(y9,z9);
A85:      FD.(x,z) = d2.[x9,z9] by A70,A71,GRFUNC_1:2
            .= d2.(x9,z9);
          FD.(x,y) = d2.[x9,y9] by A70,A71,GRFUNC_1:2
            .= d2.(x9,y9);
          hence thesis by A84,A85,LATTICE5:def 7;
        end;
      end;
    end;
    suppose
      l <= k;
      then
A86:  A2 c= A1 by A60,A68,Th30,A59,A67;
      thus FD.(x,y) "\/" FD.(y,z) >= FD.(x,z)
      proof
        per cases;
        suppose
          k <= n;
          then
A87:      A1 c= A3 by A60,A76,Th30,A59,A75;
          then A2 c= A3 by A86;
          then reconsider
          x9 = x, y9 = y, z9 = z as Element of A3
    by A61,A69,A72,A74,A75,A87;
A88:      FD.(y,z) = d3.[y9,z9] by A78,A79,GRFUNC_1:2
            .= d3.(y9,z9);
A89:      FD.(x,z) = d3.[x9,z9] by A78,A79,GRFUNC_1:2
            .= d3.(x9,z9);
          FD.(x,y) = d3.[x9,y9] by A78,A79,GRFUNC_1:2
            .= d3.(x9,y9);
          hence thesis by A88,A89,LATTICE5:def 7;
        end;
        suppose
          n <= k;
          then A3 c= A1 by A60,A76,Th30,A59,A75;
          then reconsider
          x9 = x, y9 = y, z9 = z as Element of A1
   by A56,A58,A59,A69,A77,A86;
A90:      FD.(y,z) = d1.[y9,z9] by A62,A63,GRFUNC_1:2
            .= d1.(y9,z9);
A91:      FD.(x,z) = d1.[x9,z9] by A62,A63,GRFUNC_1:2
            .= d1.(x9,z9);
          FD.(x,y) = d1.[x9,y9] by A62,A63,GRFUNC_1:2
            .= d1.(x9,y9);
          hence thesis by A90,A91,LATTICE5:def 7;
        end;
      end;
    end;
  end;
  FD is zeroed
  proof
    let x be Element of FS;
    consider y being set such that
A92: x in y and
A93: y in X by A1,TARSKI:def 4;
    consider j being Element of NAT such that
A94: y = (S.j)`1 by A93;
    consider A1 being non empty set, d1 being distance_function of A1,L, Aq1
    being non empty set, dq1 being distance_function of Aq1,L such that
    Aq1, dq1 is_extension2_of A1,d1 and
A95: S.j = [A1,d1] and
    S.(j+1) = [Aq1,dq1] by Def11;
 [A1,d1]`2 = d1;
    then d1 in the set of all  (S.i)`2 where i is Element of NAT by A95;
    then
A96: d1 c= FD by ZFMISC_1:74;
    reconsider x9 = x as Element of A1 by A92,A94,A95;
    dom d1 = [:A1,A1:] by FUNCT_2:def 1;
    hence FD.(x,x) = d1.[x9,x9] by A96,GRFUNC_1:2
      .= d1.(x9,x9)
      .= Bottom L by LATTICE5:def 6;
  end;
  hence thesis by A38,A55;
end;

theorem Th33:
  for L be lower-bounded modular LATTICE for S being ExtensionSeq2
  of the carrier of L, BasicDF(L) for FS being non empty set for FD being
distance_function of FS,L for x,y being Element of FS for a,b being Element of
L st FS = union the set of all  (S.i)`1 where i is Element of NAT & FD =
  union the set of all  (S.i)`2 where i is Element of NAT & FD.(x,y) <= a
  "\/"b ex z1,z2 being Element of FS st FD.(x,z1) = a & FD.(z1,z2) = (FD.(x,y)
  "\/"a)"/\"b & FD.(z2,y) = a
proof
  let L be lower-bounded modular LATTICE;
  let S be ExtensionSeq2 of the carrier of L, BasicDF(L);
  let FS be non empty set, FD be distance_function of FS,L;
  let x,y be Element of FS;
  let a,b be Element of L;
  assume that
A1: FS = union the set of all  (S.i)`1 where i is Element of NAT and
A2: FD = union the set of all  (S.i)`2 where i is Element of NAT and
A3: FD.(x,y) <= a"\/"b;
  (S.0)`1 in the set of all  (S.i)`1 where i is Element of NAT;
  then reconsider
  X = the set of all  (S.i)`1 where i is Element of NAT as
  non empty set;
  consider x1 being set such that
A4: x in x1 and
A5: x1 in X by A1,TARSKI:def 4;
  consider k being Element of NAT such that
A6: x1 = (S.k)`1 by A5;
  consider A1 being non empty set, d1 being distance_function of A1,L, Aq1
  being non empty set, dq1 being distance_function of Aq1,L such that
A7: Aq1, dq1 is_extension2_of A1,d1 and
A8: S.k = [A1,d1] and
A9: S.(k+1) = [Aq1,dq1] by Def11;
A10: [A1,d1]`1 = A1;
A11: x in A1 by A4,A6,A8;
  [A1,d1]`2 = d1;
  then d1 in the set of all  (S.i)`2 where i is Element of NAT by A8;
  then
A12: d1 c= FD by A2,ZFMISC_1:74;
A13: [Aq1,dq1]`1 = Aq1;
  then Aq1 in the set of all  (S.i)`1 where i is Element of NAT by A9;
  then
A14: Aq1 c= FS by A1,ZFMISC_1:74;
  [Aq1,dq1]`2 = dq1;
  then dq1 in the set of all  (S.i)`2 where i is Element of NAT by A9;
  then
A15: dq1 c= FD by A2,ZFMISC_1:74;
  consider y1 being set such that
A16: y in y1 and
A17: y1 in X by A1,TARSKI:def 4;
  consider l being Element of NAT such that
A18: y1 = (S.l)`1 by A17;
  consider A2 being non empty set, d2 being distance_function of A2,L, Aq2
  being non empty set, dq2 being distance_function of Aq2,L such that
A19: Aq2, dq2 is_extension2_of A2,d2 and
A20: S.l = [A2,d2] and
A21: S.(l+1) = [Aq2,dq2] by Def11;
A22: [A2,d2]`1 = A2;
A23: y in A2 by A16,A18,A20;
  [A2,d2]`2 = d2;
  then d2 in the set of all  (S.i)`2 where i is Element of NAT by A20;
  then
A24: d2 c= FD by A2,ZFMISC_1:74;
A25: [Aq2,dq2]`1 = Aq2;
  then Aq2 in the set of all  (S.i)`1 where i is Element of NAT by A21;
  then
A26: Aq2 c= FS by A1,ZFMISC_1:74;
  [Aq2,dq2]`2 = dq2;
  then dq2 in the set of all  (S.i)`2 where i is Element of NAT by A21;
  then
A27: dq2 c= FD by A2,ZFMISC_1:74;
  per cases;
  suppose
    k <= l;
    then A1 c= A2 by A10,A22,Th30,A8,A20;
    then reconsider x9=x,y9=y as Element of A2
      by A11,A16,A18,A20;
    A2 c= Aq2 by A22,A25,Th30,A20,A21,NAT_1:11;
    then reconsider x99 = x9,y99 = y9 as Element of Aq2;
    dom d2 = [:A2,A2:] by FUNCT_2:def 1;
    then
A28: FD.(x,y) = d2.[x9,y9] by A24,GRFUNC_1:2
      .= d2.(x9,y9);
    then consider z1,z2 being Element of Aq2 such that
A29: dq2.(x,z1) = a and
A30: dq2.(z1,z2) = (d2.(x9,y9)"\/"a)"/\"b and
A31: dq2.(z2,y) = a by A3,A19,Th29;
    reconsider z19 = z1, z29 = z2 as Element of FS by A26;
    take z19,z29;
A32: dom dq2 = [:Aq2,Aq2:] by FUNCT_2:def 1;
    hence FD.(x,z19) = dq2.[x99,z1] by A27,GRFUNC_1:2
      .= a by A29;
    thus FD.(z19,z29) = dq2.[z1,z2] by A27,A32,GRFUNC_1:2
      .= (FD.(x,y)"\/"a)"/\"b by A28,A30;
    thus FD.(z29,y) = dq2.[z2,y99] by A27,A32,GRFUNC_1:2
      .= a by A31;
  end;
  suppose
    l <= k;
    then A2 c= A1 by A10,A22,Th30,A8,A20;
    then reconsider x9=x,y9=y as Element of A1 by A4,A6,A8,A23;
    A1 c= Aq1 by A10,A13,Th30,A8,A9,NAT_1:11;
    then reconsider x99 = x9,y99 = y9 as Element of Aq1;
    dom d1 = [:A1,A1:] by FUNCT_2:def 1;
    then
A33: FD.(x,y) = d1.[x9,y9] by A12,GRFUNC_1:2
      .= d1.(x9,y9);
    then consider z1,z2 being Element of Aq1 such that
A34: dq1.(x,z1) = a and
A35: dq1.(z1,z2) = (d1.(x9,y9)"\/"a)"/\"b and
A36: dq1.(z2,y) = a by A3,A7,Th29;
    reconsider z19 = z1, z29 = z2 as Element of FS by A14;
    take z19,z29;
A37: dom dq1 = [:Aq1,Aq1:] by FUNCT_2:def 1;
    hence FD.(x,z19) = dq1.[x99,z1] by A15,GRFUNC_1:2
      .= a by A34;
    thus FD.(z19,z29) = dq1.[z1,z2] by A15,A37,GRFUNC_1:2
      .= (FD.(x,y)"\/"a)"/\"b by A33,A35;
    thus FD.(z29,y) = dq1.[z2,y99] by A15,A37,GRFUNC_1:2
      .= a by A36;
  end;
end;

Lm3: for m being Element of NAT st m in Seg 4 holds (m = 1 or m = 2 or m = 3
or m = 4)
proof
  let m be Element of NAT;
  assume
A1: m in Seg 4;
  then m <= 4 by FINSEQ_1:1;
  then m = 0 or ... or m = 4 by NAT_1:60;
  hence thesis by A1,FINSEQ_1:1;
end;

Lm4: for j being Nat st 1 <= j & j < 4 holds j = 1 or j = 2 or j = 3
proof
  let j be Nat;
  assume that
A1: 1 <= j and
A2: j < 4;
  j < 3+1 by A2;
  then j <= 3 by NAT_1:13;
  then j = 0 or ... or j = 3 by NAT_1:60;
  hence thesis by A1;
end;

theorem Th34:
  for L be lower-bounded modular LATTICE for S being ExtensionSeq2
  of the carrier of L, BasicDF(L) for FS being non empty set for FD being
distance_function of FS,L for f being Homomorphism of L,EqRelLATT FS for e1,e2
being Equivalence_Relation of FS
for x,y being object st f = alpha FD & FS = union
the set of all  (S.i)`1 where i is Element of NAT & FD = union the set of all
 (S.i)`2
where i is Element of NAT & e1 in the carrier of Image f &
  e2 in the carrier of Image f & [x,y] in e1 "\/" e2 ex F being non empty
  FinSequence of FS st len F = 2+2 & x,y are_joint_by F,e1,e2
proof
  let L be lower-bounded modular LATTICE;
  let S be ExtensionSeq2 of the carrier of L, BasicDF(L);
  let FS be non empty set;
  let FD be distance_function of FS,L;
  let f be Homomorphism of L,EqRelLATT FS;
  let e1,e2 be Equivalence_Relation of FS;
  let x,y be object;
  assume that
A1: f = alpha FD and
A2: FS = union the set of all  (S.i)`1 where i is Element of NAT &
  FD = union the set of all  (S.i)`2 where i is Element of NAT and
A3: e1 in the carrier of Image f and
A4: e2 in the carrier of Image f and
A5: [x,y] in e1 "\/" e2;
A6: the carrier of Image f = rng f by YELLOW_0:def 15;
  then consider a being object such that
A7: a in dom f and
A8: e1 = f.a by A3,FUNCT_1:def 3;
  consider b being object such that
A9: b in dom f and
A10: e2 = f.b by A4,A6,FUNCT_1:def 3;
  reconsider a,b as Element of L by A7,A9;
  reconsider a,b as Element of L;
  consider e being Equivalence_Relation of FS such that
A11: e = f.(a"\/"b) and
A12: for u,v being Element of FS holds [u,v] in e iff FD.(u,v) <= a"\/"b
  by A1,LATTICE5:def 8;
  consider e29 being Equivalence_Relation of FS such that
A13: e29 = f.b and
A14: for u,v being Element of FS holds [u,v] in e29 iff FD.(u,v) <= b by A1,
LATTICE5:def 8;
  consider e19 being Equivalence_Relation of FS such that
A15: e19 = f.a and
A16: for u,v being Element of FS holds [u,v] in e19 iff FD.(u,v) <= a by A1,
LATTICE5:def 8;
  field (e1 "\/" e2) = FS by ORDERS_1:12;
  then reconsider u = x, v = y as Element of FS by A5,RELAT_1:15;
A17: Seg 4 = { n where n is Nat: 1 <= n & n <= 4 } by FINSEQ_1:def 1;
  then
A18: 1 in Seg 4;
  e = f.a"\/"f.b by A11,WAYBEL_6:2
    .= e1 "\/" e2 by A8,A10,LATTICE5:10;
  then
A19: FD.(u,v) <= a"\/"b by A5,A12;
  then consider z1,z2 being Element of FS such that
A20: FD.(u,z1) = a and
A21: FD.(z1,z2) = (FD.(u,v)"\/"a)"/\"b and
A22: FD.(z2,v) = a by A2,Th33;
  defpred P[set,object] means
($1 = 1 implies $2 = u) & ($1 = 2 implies $2 = z1)
  & ($1 = 3 implies $2 = z2) & ($1 = 4 implies $2 = v);
A23: for m being Nat st m in Seg 4 ex w being object st P[m,w]
  proof
    let m be Nat;
    assume
A24: m in Seg 4;
    per cases by A24,Lm3;
    suppose
A25:  m = 1;
      take x;
      thus thesis by A25;
    end;
    suppose
A26:  m = 2;
      take z1;
      thus thesis by A26;
    end;
    suppose
A27:  m = 3;
      take z2;
      thus thesis by A27;
    end;
    suppose
A28:  m = 4;
      take y;
      thus thesis by A28;
    end;
  end;
  ex p being FinSequence st dom p = Seg 4 & for k being Nat st k in Seg 4
  holds P[k,p.k] from FINSEQ_1:sch 1(A23);
  then consider h being FinSequence such that
A29: dom h = Seg 4 and
A30: for m being Nat st m in Seg 4 holds (m = 1 implies h.m = u) & (m =
  2 implies h.m = z1) & (m = 3 implies h.m = z2) & (m = 4 implies h.m = v);
A31: len h = 4 by A29,FINSEQ_1:def 3;
A32: 3 in Seg 4 by A17;
A33: 4 in Seg 4 by A17;
A34: 2 in Seg 4 by A17;
  rng h c= FS
  proof
    let w be object;
    assume w in rng h;
    then consider j be object such that
A35: j in dom h and
A36: w = h.j by FUNCT_1:def 3;
    per cases by A29,A35,Lm3;
    suppose
      j = 1;
      then h.j = u by A30,A18;
      hence thesis by A36;
    end;
    suppose
      j = 2;
      then h.j = z1 by A30,A34;
      hence thesis by A36;
    end;
    suppose
      j = 3;
      then h.j = z2 by A30,A32;
      hence thesis by A36;
    end;
    suppose
      j = 4;
      then h.j = v by A30,A33;
      hence thesis by A36;
    end;
  end;
  then reconsider h as FinSequence of FS by FINSEQ_1:def 4;
  len h <> 0 by A29,FINSEQ_1:def 3;
  then reconsider h as non empty FinSequence of FS;
A37: h.1 = x by A30,A18;
A38: for j being Element of NAT st 1 <= j & j < len h holds (j is odd
  implies [h.j,h.(j+1)] in e1) & (j is even implies [h.j,h.(j+1)] in e2)
  proof
    let j be Element of NAT;
    assume
A39: 1 <= j & j < len h;
    per cases by A31,A39,Lm4;
    suppose
A40:  j = 1;
      [u,z1] in e19 by A16,A20;
      then [h.1,z1] in e19 by A30,A18;
      hence thesis by A8,A15,A30,A34,A40;
    end;
    suppose
A41:  j = 2;
      FD.(u,v)"\/"a <= a"\/"b"\/"a by A19,WAYBEL_1:2;
      then FD.(u,v)"\/"a <= b"\/"(a"\/"a) by LATTICE3:14;
      then FD.(u,v)"\/"a <= b"\/"a by YELLOW_5:1;
      then (FD.(u,v)"\/"a)"/\"b <= b"/\"(b"\/"a) by WAYBEL_1:1;
      then (FD.(u,v)"\/"a)"/\"b <= b by LATTICE3:18;
      then [z1,z2] in e29 by A14,A21;
      then
A42:  [h.2,z2] in e29 by A30,A34;
      consider i being Element of NAT such that
A43:  i = 1;
      2*i = j by A41,A43;
      hence thesis by A10,A13,A30,A32,A41,A42;
    end;
    suppose
A44:  j = 3;
      [z2,v] in e19 by A16,A22;
      then
A45:  [h.3,v] in e19 by A30,A32;
      consider i being Element of NAT such that
A46:  i = 1;
      2*i+1 = j by A44,A46;
      hence thesis by A8,A15,A30,A33,A44,A45;
    end;
  end;
  take h;
  thus len h = 2+2 by A29,FINSEQ_1:def 3;
  h.(len h) = h.4 by A29,FINSEQ_1:def 3
    .= y by A30,A33;
  hence thesis by A37,A38;
end;

theorem Th35:
  for L be lower-bounded modular LATTICE holds L
  has_a_representation_of_type<= 2
proof
  let L be lower-bounded modular LATTICE;
  set A = the carrier of L, D = BasicDF(L);
  set S = the ExtensionSeq2 of A,D;
  set FS = union the set of all  (S.i)`1 where i is Element of NAT;
A1: (S.0)`1 in the set of all  (S.i)`1 where i is Element of NAT;
A2: S.0 = [A,D] by Def11;
  A c= FS by A1,A2,ZFMISC_1:74;
  then reconsider FS as non empty set;
  reconsider FD = union the set of all  (S.i)`2 where i is Element of NAT
 as distance_function of FS,L by Th32;
  alpha FD is join-preserving
  proof
    set f = alpha FD;
    let a,b be Element of L;
A3: ex_sup_of f.:{a,b},EqRelLATT FS by YELLOW_0:17;
    consider e2 being Equivalence_Relation of FS such that
A4: e2 = f.b and
A5: for x,y being Element of FS holds [x,y] in e2 iff FD.(x,y) <= b
    by LATTICE5:def 8;
    consider e1 being Equivalence_Relation of FS such that
A6: e1 = f.a and
A7: for x,y being Element of FS holds [x,y] in e1 iff FD.(x,y) <= a
    by LATTICE5:def 8;
    consider e3 being Equivalence_Relation of FS such that
A8: e3 = f.(a "\/" b) and
A9: for x,y being Element of FS holds [x,y] in e3 iff FD.(x,y) <= a
    "\/"b by LATTICE5:def 8;
A10: field e2 = FS by ORDERS_1:12;
    now
      let x,y be object;
A11:  b <= b "\/" a by YELLOW_0:22;
      assume
A12:  [x,y] in e2;
      then reconsider x9 = x, y9 = y as Element of FS by A10,RELAT_1:15;
      FD.(x9,y9) <= b by A5,A12;
      then FD.(x9,y9) <= b "\/" a by A11,ORDERS_2:3;
      hence [x,y] in e3 by A9;
    end;
    then
A13: e2 c= e3;
A14: field e3 = FS by ORDERS_1:12;
    for u,v being object holds [u,v] in e3 implies [u,v] in e1 "\/" e2
    proof
      let u,v be object;
A15:  Seg 4 = { n where n is Nat: 1 <= n & n <= 4 } by FINSEQ_1:def 1;
      then
A16:  3 in Seg 4;
      assume
A17:  [u,v] in e3;
      then reconsider x = u, y = v as Element of FS by A14,RELAT_1:15;
A18:  FD.(x,y) <= a"\/"b by A9,A17;
      then consider z1,z2 being Element of FS such that
A19:  FD.(x,z1) = a and
A20:  FD.(z1,z2) = (FD.(x,y)"\/"a)"/\"b and
A21:  FD.(z2,y) = a by Th33;
A22:  u in FS by A14,A17,RELAT_1:15;
      defpred P[set,object] means
($1 = 1 implies $2 = x) & ($1 = 2 implies $2 =
      z1) & ($1 = 3 implies $2 = z2) & ($1 = 4 implies $2 = y);
A23:  for m being Nat st m in Seg 4 ex w being object st P[m,w]
      proof
        let m be Nat;
        assume
A24:    m in Seg 4;
        per cases by A24,Lm3;
        suppose
A25:      m = 1;
          take x;
          thus thesis by A25;
        end;
        suppose
A26:      m = 2;
          take z1;
          thus thesis by A26;
        end;
        suppose
A27:      m = 3;
          take z2;
          thus thesis by A27;
        end;
        suppose
A28:      m = 4;
          take y;
          thus thesis by A28;
        end;
      end;
      ex p being FinSequence st dom p = Seg 4 & for k being Nat st k in
      Seg 4 holds P[k,p.k] from FINSEQ_1:sch 1(A23);
      then consider h being FinSequence such that
A29:  dom h = Seg 4 and
A30:  for m being Nat st m in Seg 4 holds (m = 1 implies h.m = x) & (
m = 2 implies h.m = z1) & (m = 3 implies h.m = z2) & (m = 4 implies h.m = y);
A31:  len h = 4 by A29,FINSEQ_1:def 3;
A32:  4 in Seg 4 by A15;
A33:  1 in Seg 4 by A15;
      then
A34:  u = h.1 by A30;
A35:  2 in Seg 4 by A15;
A36:  for j being Nat st 1 <= j & j < len h holds [h.j,h.(j+1)
      ] in e1 \/ e2
      proof
        let j be Nat;
        assume
A37:    1 <= j & j < len h;
        per cases by A31,A37,Lm4;
        suppose
A38:      j = 1;
          [x,z1] in e1 by A7,A19;
          then [h.1,z1] in e1 by A30,A33;
          then [h.1,h.2] in e1 by A30,A35;
          hence thesis by A38,XBOOLE_0:def 3;
        end;
        suppose
A39:      j = 2;
          FD.(x,y)"\/"a <= a"\/"b"\/"a by A18,WAYBEL_1:2;
          then FD.(x,y)"\/"a <= b"\/"(a"\/"a) by LATTICE3:14;
          then FD.(x,y)"\/"a <= b"\/"a by YELLOW_5:1;
          then (FD.(x,y)"\/"a)"/\"b <= b"/\"(b"\/"a) by WAYBEL_1:1;
          then (FD.(x,y)"\/"a)"/\"b <= b by LATTICE3:18;
          then [z1,z2] in e2 by A5,A20;
          then [h.2,z2] in e2 by A30,A35;
          then [h.2,h.3] in e2 by A30,A16;
          hence thesis by A39,XBOOLE_0:def 3;
        end;
        suppose
A40:      j = 3;
          [z2,y] in e1 by A7,A21;
          then [h.3,y] in e1 by A30,A16;
          then [h.3,h.4] in e1 by A30,A32;
          hence thesis by A40,XBOOLE_0:def 3;
        end;
      end;
      v = h.4 by A30,A32
        .= h.(len h) by A29,FINSEQ_1:def 3;
      hence thesis by A22,A31,A34,A36,EQREL_1:28;
    end;
    then
A41: e3 c= e1 "\/" e2;
A42: field e1 = FS by ORDERS_1:12;
    now
      let x,y be object;
A43:  a <= a "\/" b by YELLOW_0:22;
      assume
A44:  [x,y] in e1;
      then reconsider x9 = x, y9 = y as Element of FS by A42,RELAT_1:15;
      FD.(x9,y9) <= a by A7,A44;
      then FD.(x9,y9) <= a "\/" b by A43,ORDERS_2:3;
      hence [x,y] in e3 by A9;
    end;
    then e1 c= e3;
    then e1 \/ e2 c= e3 by A13,XBOOLE_1:8;
    then
A45: e1 "\/" e2 c= e3 by EQREL_1:def 2;
    dom f = the carrier of L by FUNCT_2:def 1;
    then sup (f.:{a,b}) = sup {f.a,f.b} by FUNCT_1:60
      .= f.a "\/" f.b by YELLOW_0:41
      .= e1 "\/" e2 by A6,A4,LATTICE5:10
      .= f.(a "\/" b) by A8,A45,A41
      .= f.sup {a,b} by YELLOW_0:41;
    hence thesis by A3;
  end;
  then reconsider f = alpha FD as Homomorphism of L,EqRelLATT FS by LATTICE5:14
;
A46: dom f = the carrier of L by FUNCT_2:def 1;
A47: ex e being Equivalence_Relation of FS st e in the carrier of Image f &
  e <> id FS
  proof
A48: {A} <> {{A}}
    proof
      assume {A} = {{A}};
      then {A} in {A} by TARSKI:def 1;
      hence contradiction;
    end;
    consider A9 being non empty set, d9 being distance_function of A9,L, Aq9
    being non empty set, dq9 being distance_function of Aq9,L such that
A49: Aq9, dq9 is_extension2_of A9,d9 and
A50: S.0 = [A9,d9] and
A51: S.(0+1) = [Aq9,dq9] by Def11;
    A9 = A & d9 = D by A2,A50,XTUPLE_0:1;
    then consider q being QuadrSeq of D such that
A52: Aq9 = NextSet2(D) and
A53: dq9 = NextDelta2(q) by A49;
    ConsecutiveSet2(A,{}) = A by Th14;
    then reconsider Q = Quadr2(q,{}) as Element of [:A,A,the carrier of L,the
    carrier of L:];
A54: (S.1)`2 in the set of all  (S.i)`2 where i is Element of NAT;
    succ {} c= DistEsti(D) by Th1;
    then {} in DistEsti(D) by ORDINAL1:21;
    then
A55: {} in dom q by LATTICE5:25;
    then q.{} in rng q by FUNCT_1:def 3;
    then q.{} in {[u,v,a9,b9] where u is Element of A, v is Element of A, a9
    is Element of L, b9 is Element of L: D.(u,v) <= a9"\/"b9} by
LATTICE5:def 13;
    then consider u,v be Element of A, a,b be Element of L such that
A56: q.{} = [u,v,a,b] and
    D.(u,v) <= a"\/"b;
    consider e being Equivalence_Relation of FS such that
A57: e = f.b and
A58: for x,y being Element of FS holds [x,y] in e iff FD.(x,y) <= b
    by LATTICE5:def 8;
    Quadr2(q,{}) = [u,v,a,b] by A55,A56,Def6;
    then
A59: b = Q`4_4;
    [Aq9,dq9]`2 = NextDelta2(q) by A53;
    then
A60: NextDelta2(q) c= FD by A54,A51,ZFMISC_1:74;
A61: {{A}} in {{A}, {{A}} } by TARSKI:def 2;
    then
A62: {{A}} in A \/ {{A}, {{A}} } by XBOOLE_0:def 3;
    take e;
    e in rng f by A46,A57,FUNCT_1:def 3;
    hence e in the carrier of Image f by YELLOW_0:def 15;
A63: (S.1)`1 in the set of all  (S.i)`1 where i is Element of NAT;
    [Aq9,dq9]`1 = NextSet2(D) by A52;
    then
A64: NextSet2(D) c= FS by A63,A51,ZFMISC_1:74;
    new_set2 A = new_set2 ConsecutiveSet2(A,{}) by Th14
      .= ConsecutiveSet2(A,succ {}) by Th15;
    then new_set2 A c= NextSet2(D) by Th1,Th21;
    then
A65: new_set2 A c= FS by A64;
A66: {{A}} in new_set2 A by A61,XBOOLE_0:def 3;
A67: {A} in {{A}, {{A}} } by TARSKI:def 2;
    then {A} in A \/ {{A}, {{A}} } by XBOOLE_0:def 3;
    then reconsider W = {A}, V = {{A}} as Element of FS by A65,A66;
A68: ConsecutiveSet2(A,{}) = A & ConsecutiveDelta2(q,{}) = D by Th14,Th18;
    ConsecutiveDelta2(q,succ {}) = new_bi_fun2(BiFun(ConsecutiveDelta2(q
    ,{}), ConsecutiveSet2(A,{}),L),Quadr2(q,{})) by Th19
      .= new_bi_fun2(D,Q) by A68,LATTICE5:def 15;
    then new_bi_fun2(D,Q) c= NextDelta2(q) by Th1,Th24;
    then
A69: new_bi_fun2(D,Q) c= FD by A60;
    dom new_bi_fun2(D,Q) = [:new_set2 A,new_set2 A:] & {A} in new_set2 A
    by A67,FUNCT_2:def 1,XBOOLE_0:def 3;
    then [{A},{{A}}] in dom new_bi_fun2(D,Q) by A62,ZFMISC_1:87;
    then FD.(W,V) = new_bi_fun2(D,Q).({A},{{A}}) by A69,GRFUNC_1:2
      .= (D.(Q`1_4,Q`2_4)"\/"(Q`3_4))"/\"(Q`4_4) by Def4;
    then FD.(W,V) <= b by A59,YELLOW_0:23;
    then [{A},{{A}}] in e by A58;
    hence thesis by A48,RELAT_1:def 10;
  end;
A70: now
    consider e being Equivalence_Relation of FS such that
    e in the carrier of Image f and
A71: e <> id FS by A47;
    assume FS is trivial;
    then consider x being object such that
A72: FS = {x} by ZFMISC_1:131;
A73: [:{x},{x}:] = {[x,x]} & id({x}) = {[x,x]} by SYSREL:13,ZFMISC_1:29;
    field e = {x} by A72,EQREL_1:9;
    then id FS c= e by A72,RELAT_2:1;
    hence contradiction by A72,A71,A73;
  end;
  D is onto by LATTICE5:40;
  then
A74: rng D = A by FUNCT_2:def 3;
  for w being object st w in A
ex z being object st z in [:FS,FS:] & w = FD . z
  proof
    let w be object;
A75: (S.0)`1 in the set of all  (S.i)`1 where i is Element of NAT;
A76: (S.0)`2 in the set of all  (S.i)`2 where i is Element of NAT;
A77: S.0 = [A,D] by Def11;
A78: D c= FD by A76,A77,ZFMISC_1:74;
    assume w in A;
    then consider z being object such that
A79: z in [:A,A:] and
A80: D.z = w by A74,FUNCT_2:11;
    take z;
    A c= FS by A75,A77,ZFMISC_1:74;
    then [:A,A:] c= [:FS,FS:] by ZFMISC_1:96;
    hence z in [:FS,FS:] by A79;
    z in dom D by A79,FUNCT_2:def 1;
    hence thesis by A80,A78,GRFUNC_1:2;
  end;
  then rng FD = A by FUNCT_2:10;
  then
A81: FD is onto by FUNCT_2:def 3;
  reconsider FS as non trivial set by A70;
  take FS;
  reconsider f as Homomorphism of L,EqRelLATT FS;
  take f;
  thus f is one-to-one by A81,LATTICE5:15;
  reconsider FD as distance_function of FS,L;
  thus Image f is finitely_typed
  proof
    take FS;
    thus for e being object st e in the carrier of Image f holds e is
    Equivalence_Relation of FS
    proof
      let e be object;
      assume e in the carrier of Image f;
      then e in rng f by YELLOW_0:def 15;
      then consider x being object such that
A82:  x in dom f and
A83:  e = f.x by FUNCT_1:def 3;
      reconsider x as Element of L by A82;
      ex E being Equivalence_Relation of FS st E = f.x & for u,v being
      Element of FS holds [u,v] in E iff FD.(u,v) <= x by LATTICE5:def 8;
      hence thesis by A83;
    end;
    take 2+2;
    thus thesis by Th34;
  end;
  thus ex e being Equivalence_Relation of FS st e in the carrier of Image f &
  e <> id FS
  proof
A84: {A} <> {{A}}
    proof
      assume {A} = {{A}};
      then {A} in {A} by TARSKI:def 1;
      hence contradiction;
    end;
    consider A9 being non empty set, d9 being distance_function of A9,L, Aq9
    being non empty set, dq9 being distance_function of Aq9,L such that
A85: Aq9, dq9 is_extension2_of A9,d9 and
A86: S.0 = [A9,d9] and
A87: S.(0+1) = [Aq9,dq9] by Def11;
    A9 = A & d9 = D by A2,A86,XTUPLE_0:1;
    then consider q being QuadrSeq of D such that
A88: Aq9 = NextSet2(D) and
A89: dq9 = NextDelta2(q) by A85;
    ConsecutiveSet2(A,{}) = A by Th14;
    then reconsider Q = Quadr2(q,{}) as Element of [:A,A,the carrier of L,the
    carrier of L:];
A90: (S.1)`2 in the set of all  (S.i)`2 where i is Element of NAT;
    succ {} c= DistEsti(D) by Th1;
    then {} in DistEsti(D) by ORDINAL1:21;
    then
A91: {} in dom q by LATTICE5:25;
    then q.{} in rng q by FUNCT_1:def 3;
    then q.{} in {[u,v,a9,b9] where u is Element of A, v is Element of A, a9
    is Element of L, b9 is Element of L: D.(u,v) <= a9"\/"b9} by
LATTICE5:def 13;
    then consider u,v be Element of A, a,b be Element of L such that
A92: q.{} = [u,v,a,b] and
    D.(u,v) <= a"\/"b;
    consider e being Equivalence_Relation of FS such that
A93: e = f.b and
A94: for x,y being Element of FS holds [x,y] in e iff FD.(x,y) <= b
    by LATTICE5:def 8;
    Quadr2(q,{}) = [u,v,a,b] by A91,A92,Def6;
    then
A95: b = Q`4_4;
    [Aq9,dq9]`2 = NextDelta2(q) by A89;
    then
A96: NextDelta2(q) c= FD by A90,A87,ZFMISC_1:74;
A97: {{A}} in {{A}, {{A}} } by TARSKI:def 2;
    then
A98: {{A}} in A \/ {{A}, {{A}} } by XBOOLE_0:def 3;
    take e;
    e in rng f by A46,A93,FUNCT_1:def 3;
    hence e in the carrier of Image f by YELLOW_0:def 15;
A99: (S.1)`1 in the set of all  (S.i)`1 where i is Element of NAT;
    [Aq9,dq9]`1 = NextSet2(D) by A88;
    then
A100: NextSet2(D) c= FS by A99,A87,ZFMISC_1:74;
    new_set2 A = new_set2 ConsecutiveSet2(A,{}) by Th14
      .= ConsecutiveSet2(A,succ {}) by Th15;
    then new_set2 A c= NextSet2(D) by Th1,Th21;
    then
A101: new_set2 A c= FS by A100;
A102: {{A}} in new_set2 A by A97,XBOOLE_0:def 3;
A103: {A} in {{A}, {{A}} } by TARSKI:def 2;
    then {A} in A \/ {{A}, {{A}} } by XBOOLE_0:def 3;
    then reconsider W = {A}, V = {{A}} as Element of FS by A101,A102;
A104: ConsecutiveSet2(A,{}) = A & ConsecutiveDelta2(q,{}) = D by Th14,Th18;
    ConsecutiveDelta2(q,succ {}) = new_bi_fun2(BiFun(ConsecutiveDelta2(q
    ,{}), ConsecutiveSet2(A,{}),L),Quadr2(q,{})) by Th19
      .= new_bi_fun2(D,Q) by A104,LATTICE5:def 15;
    then new_bi_fun2(D,Q) c= NextDelta2(q) by Th1,Th24;
    then
A105: new_bi_fun2(D,Q) c= FD by A96;
    dom new_bi_fun2(D,Q) = [:new_set2 A,new_set2 A:] & {A} in new_set2 A
    by A103,FUNCT_2:def 1,XBOOLE_0:def 3;
    then [{A},{{A}}] in dom new_bi_fun2(D,Q) by A98,ZFMISC_1:87;
    then FD.(W,V) = new_bi_fun2(D,Q).({A},{{A}}) by A105,GRFUNC_1:2
      .= (D.(Q`1_4,Q`2_4)"\/"(Q`3_4))"/\"(Q`4_4) by Def4;
    then FD.(W,V) <= b by A95,YELLOW_0:23;
    then [{A},{{A}}] in e by A94;
    hence thesis by A84,RELAT_1:def 10;
  end;
  for e1,e2 being Equivalence_Relation of FS
for x,y being object st e1 in
the carrier of Image f & e2 in the carrier of Image f & [x,y] in e1 "\/" e2 ex
  F being non empty FinSequence of FS st len F = 2+2 & x,y are_joint_by F,e1,e2
  by Th34;
  hence thesis by A47,LATTICE5:13;
end;

::  <=>  ::   L has_a_representation_of_type<= 2 iff L is modular

::$N Jonsson Theorem for modular lattices
theorem
  for L be lower-bounded LATTICE holds L has_a_representation_of_type<=
  2 iff L is modular by Th9,Th35;