LATSUM_1

index · ← NDIFF_1 · NAGATA_1 →
:: The Operation of Addition of Relational Structures
::  by Katarzyna Romanowicz and Adam Grabowski
::
:: Received May 24, 2004
:: Copyright (c) 2004-2026 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 XBOOLE_0, ORDERS_2, PARTFUN1, STRUCT_0, FINSEQ_1, RELAT_1,
      TARSKI, RELAT_2, SUBSET_1, XXREAL_0, LATTICE3, WAYBEL_0, EQREL_1,
      LATTICES;
 notations XBOOLE_0, TARSKI, SUBSET_1, RELSET_1, RELAT_2, STRUCT_0, ORDERS_2,
      YELLOW_0, WAYBEL_0, LATTICE3;
 constructors LATTICE3, WAYBEL_0, RELSET_1;
 registrations XBOOLE_0, RELSET_1, STRUCT_0, WAYBEL_0;
 requirements SUBSET, BOOLE;
 definitions RELAT_2;
 expansions RELAT_2;
 theorems ZFMISC_1, RELAT_1, RELSET_1, ORDERS_2, XBOOLE_0, XBOOLE_1, WAYBEL_0,
      YELLOW_0, YELLOW_5;

begin

theorem
  for x, y, A, B being set st x in A \/ B & y in A \/ B holds x in A \ B
  & y in A \ B or x in B & y in B or x in A \ B & y in B or x in B & y in A \ B
proof
  let x, y, A, B be set;
  assume
A1: x in A \/ B & y in A \/ B;
  A \/ B = (A \ B) \/ B by XBOOLE_1:39;
  hence thesis by A1,XBOOLE_0:def 3;
end;

definition
  let R, S be RelStr;
  pred R tolerates S means

  for x, y being set st x in (the carrier of R
) /\ (the carrier of S) & y in (the carrier of R) /\ (the carrier of S) holds [
  x, y] in the InternalRel of R iff [x,y] in the InternalRel of S;
end;

begin

definition
  let R, S be RelStr; :: Wronski Sum Operation
  func R [*] S -> strict RelStr means
  :Def2:
  the carrier of it = (the carrier
of R) \/ (the carrier of S) & the InternalRel of it = (the InternalRel of R) \/
  (the InternalRel of S) \/ ((the InternalRel of R) * the InternalRel of S);
  existence
  proof
    set X = (the carrier of R) \/ (the carrier of S);
    the carrier of R c= X & the carrier of S c= X by XBOOLE_1:7;
    then reconsider
    G = (the InternalRel of R) * the InternalRel of S as Relation
    of X by RELSET_1:7;
    the carrier of R c= X & the carrier of S c= X by XBOOLE_1:7;
    then reconsider IR = the InternalRel of R, IS = the InternalRel of S as
    Relation of X by RELSET_1:7;
    set F = IR \/ IS \/ G;
    reconsider F as Relation of X;
    take RelStr (# X, F #);
    thus thesis;
  end;
  uniqueness;
end;

registration
  let R be RelStr, S be non empty RelStr;
  cluster R [*] S -> non empty;
  coherence
  proof
    (the carrier of R) \/ (the carrier of S) <> {};
    hence thesis by Def2;
  end;
end;

registration
  let R be non empty RelStr, S be RelStr;
  cluster R [*] S -> non empty;
  coherence
  proof
    (the carrier of R) \/ (the carrier of S) <> {};
    hence thesis by Def2;
  end;
end;

theorem Th2:
  for R, S being RelStr holds the InternalRel of R c= the
  InternalRel of R [*] S & the InternalRel of S c= the InternalRel of R [*] S
proof
  let R, S be RelStr;
  the InternalRel of R c= (the InternalRel of R) \/ (the InternalRel of S)
  & ( the InternalRel of R) \/ (the InternalRel of S) c= (the InternalRel of R)
  \/ ( the InternalRel of S) \/ ((the InternalRel of R) * the InternalRel of S)
  by XBOOLE_1:7;
  then
  the InternalRel of R c= (the InternalRel of R) \/ (the InternalRel of S)
  \/ ((the InternalRel of R) * the InternalRel of S) by XBOOLE_1:1;
  hence the InternalRel of R c= the InternalRel of R [*] S by Def2;
  the InternalRel of S c= (the InternalRel of R) \/ (the InternalRel of S)
  & ( the InternalRel of R) \/ (the InternalRel of S) c= (the InternalRel of R)
  \/ ( the InternalRel of S) \/ ((the InternalRel of R) * the InternalRel of S)
  by XBOOLE_1:7;
  then
  the InternalRel of S c= (the InternalRel of R) \/ (the InternalRel of S)
  \/ ((the InternalRel of R) * the InternalRel of S) by XBOOLE_1:1;
  hence thesis by Def2;
end;

theorem Th3:
  for R, S being RelStr st R is reflexive & S is reflexive holds R
  [*] S is reflexive
proof
  let R, S be RelStr;
  assume R is reflexive & S is reflexive;
  then
A1: the InternalRel of R is_reflexive_in the carrier of R & the InternalRel
  of S is_reflexive_in the carrier of S by ORDERS_2:def 2;
A2: the InternalRel of R c= the InternalRel of R [*] S & the InternalRel of
  S c= the InternalRel of R [*] S by Th2;
  the InternalRel of R [*] S is_reflexive_in the carrier of R [*] S
  proof
    let x be object;
    assume x in the carrier of R [*] S;
    then x in (the carrier of R) \/ (the carrier of S) by Def2;
    then x in the carrier of R or x in the carrier of S by XBOOLE_0:def 3;
    then
    [x,x] in the InternalRel of R or [x,x] in the InternalRel of S by A1;
    hence thesis by A2;
  end;
  hence thesis by ORDERS_2:def 2;
end;

begin

theorem Th4: :: theorem 3.1 (vii)
  for R, S being RelStr, a, b being set st [a,b] in the InternalRel
of R [*] S & a in the carrier of R & b in the carrier of R & R tolerates S & R
  is transitive holds [a,b] in the InternalRel of R
proof
  let R, S be RelStr, a, b be set;
  assume that
A1: [a,b] in the InternalRel of R [*] S and
A2: a in the carrier of R and
A3: b in the carrier of R and
A4: R tolerates S and
A5: R is transitive;
  [a,b] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
  InternalRel of R) * the InternalRel of S) by A1,Def2;
  then
A6: [a,b] in (the InternalRel of R) \/ (the InternalRel of S) or [a,b] in ((
  the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
  assume
A7: not [a,b] in the InternalRel of R;
  per cases by A7,A6,XBOOLE_0:def 3;
  suppose
A8: [a,b] in the InternalRel of S;
    then b in the carrier of S by ZFMISC_1:87;
    then
A9: b in (the carrier of R) /\ (the carrier of S) by A3,XBOOLE_0:def 4;
    a in the carrier of S by A8,ZFMISC_1:87;
    then a in (the carrier of R) /\ (the carrier of S) by A2,XBOOLE_0:def 4;
    hence thesis by A4,A7,A8,A9;
  end;
  suppose
A10: [a,b] in ((the InternalRel of R) * the InternalRel of S);
    then b in the carrier of S by ZFMISC_1:87;
    then
A11: b in (the carrier of R) /\ (the carrier of S) by A3,XBOOLE_0:def 4;
A12: the InternalRel of R is_transitive_in the carrier of R by A5,
ORDERS_2:def 3;
    consider z being object such that
A13: [a,z] in the InternalRel of R and
A14: [z,b] in the InternalRel of S by A10,RELAT_1:def 8;
A15: z in the carrier of R by A13,ZFMISC_1:87;
    z in the carrier of S by A14,ZFMISC_1:87;
    then z in (the carrier of R) /\ (the carrier of S) by A15,XBOOLE_0:def 4;
    then [z,b] in the InternalRel of R by A4,A11,A14;
    hence thesis by A2,A3,A7,A13,A15,A12;
  end;
end;

theorem Th5: :: theorem 3.1 (viii)
  for R, S being RelStr, a, b being set st [a,b] in the InternalRel
of R [*] S & a in the carrier of S & b in the carrier of S & R tolerates S & S
  is transitive holds [a,b] in the InternalRel of S
proof
  let R, S be RelStr, a, b be set;
  assume that
A1: [a,b] in the InternalRel of R [*] S and
A2: a in the carrier of S and
A3: b in the carrier of S and
A4: R tolerates S and
A5: S is transitive;
  [a,b] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
  InternalRel of R) * the InternalRel of S) by A1,Def2;
  then
A6: [a,b] in (the InternalRel of R) \/ (the InternalRel of S) or [a,b] in ((
  the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
  assume
A7: not [a,b] in the InternalRel of S;
  per cases by A7,A6,XBOOLE_0:def 3;
  suppose
A8: [a,b] in the InternalRel of R;
    then b in the carrier of R by ZFMISC_1:87;
    then
A9: b in (the carrier of R) /\ (the carrier of S) by A3,XBOOLE_0:def 4;
    a in the carrier of R by A8,ZFMISC_1:87;
    then a in (the carrier of R) /\ (the carrier of S) by A2,XBOOLE_0:def 4;
    hence thesis by A4,A7,A8,A9;
  end;
  suppose
A10: [a,b] in ((the InternalRel of R) * the InternalRel of S);
    then a in the carrier of R by ZFMISC_1:87;
    then
A11: a in (the carrier of R) /\ (the carrier of S) by A2,XBOOLE_0:def 4;
A12: the InternalRel of S is_transitive_in the carrier of S by A5,
ORDERS_2:def 3;
    consider z being object such that
A13: [a,z] in the InternalRel of R and
A14: [z,b] in the InternalRel of S by A10,RELAT_1:def 8;
A15: z in the carrier of S by A14,ZFMISC_1:87;
    z in the carrier of R by A13,ZFMISC_1:87;
    then z in (the carrier of R) /\ (the carrier of S) by A15,XBOOLE_0:def 4;
    then [a,z] in the InternalRel of S by A4,A11,A13;
    hence thesis by A2,A3,A7,A14,A15,A12;
  end;
end;

theorem Th6: :: a version of 3.1 (vii, viii - left to right)
  for R, S being RelStr, a, b being object holds ([a,b] in the
  InternalRel of R implies [a,b] in the InternalRel of R [*] S) & ([a,b] in the
  InternalRel of S implies [a,b] in the InternalRel of R [*] S)
proof
  let R, S be RelStr, a, b be object;
  thus [a,b] in the InternalRel of R implies [a,b] in the InternalRel of R [*]
  S
  proof
    assume [a,b] in the InternalRel of R;
    then [a,b] in (the InternalRel of R) \/ (the InternalRel of S) by
XBOOLE_0:def 3;
    then [a,b] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
    InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
    hence thesis by Def2;
  end;
  assume [a,b] in the InternalRel of S;
  then [a,b] in (the InternalRel of R) \/ (the InternalRel of S) by
XBOOLE_0:def 3;
  then [a,b] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
  InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
  hence thesis by Def2;
end;

theorem
  for R, S being non empty RelStr, x being Element of R [*] S holds x in
  the carrier of R or x in (the carrier of S) \ (the carrier of R)
proof
  let R, S be non empty RelStr, x be Element of R [*] S;
  x in the carrier of R [*] S;
  then x in (the carrier of S) \/ (the carrier of R) by Def2;
  then
  x in (the carrier of R) \/ ((the carrier of S) \ (the carrier of R)) by
XBOOLE_1:39;
  hence thesis by XBOOLE_0:def 3;
end;

theorem Th8: :: theorem 3.1 (vii)
  for R, S being non empty RelStr for x, y being Element of R, a, b
  being Element of R [*] S st x = a & y = b & R tolerates S & R is transitive
  holds x <= y iff a <= b
proof
  let R, S be non empty RelStr, x, y be Element of R, a, b be Element of R [*]
  S;
  assume
A1: x = a & y = b;
  assume
A2: R tolerates S & R is transitive;
  hereby
    assume x <= y;
    then [x,y] in the InternalRel of R by ORDERS_2:def 5;
    then [a,b] in the InternalRel of R [*] S by A1,Th6;
    hence a <= b by ORDERS_2:def 5;
  end;
  assume a <= b;
  then [a,b] in the InternalRel of R [*] S by ORDERS_2:def 5;
  then [x,y] in the InternalRel of R by A1,A2,Th4;
  hence thesis by ORDERS_2:def 5;
end;

theorem Th9: :: theorem 3.1 (viii)
  for R, S being non empty RelStr, a, b being Element of R [*] S, c
, d being Element of S st a = c & b = d & R tolerates S & S is transitive holds
  a <= b iff c <= d
proof
  let R, S be non empty RelStr, a, b be Element of R [*] S, c, d be Element of
  S;
  assume that
A1: a = c & b = d and
A2: R tolerates S & S is transitive;
  hereby
    assume a <= b;
    then [a,b] in the InternalRel of R [*] S by ORDERS_2:def 5;
    then [c,d] in the InternalRel of S by A1,A2,Th5;
    hence c <= d by ORDERS_2:def 5;
  end;
  assume c <= d;
  then [c,d] in the InternalRel of S by ORDERS_2:def 5;
  then [a,b] in the InternalRel of R [*] S by A1,Th6;
  hence thesis by ORDERS_2:def 5;
end;

theorem Th10:
  for R, S being antisymmetric reflexive transitive with_suprema
  non empty RelStr for x being set st x in the carrier of R holds x is Element
  of R [*] S
proof
  let R, S be antisymmetric reflexive transitive with_suprema non empty
  RelStr;
  let x be set;
  assume x in the carrier of R;
  then x in (the carrier of R) \/ (the carrier of S) by XBOOLE_0:def 3;
  hence thesis by Def2;
end;

theorem
  for R, S being antisymmetric reflexive transitive with_suprema non
empty RelStr for x being set st x in the carrier of S holds x is Element of R
  [*] S
proof
  let R, S be antisymmetric reflexive transitive with_suprema non empty
  RelStr;
  let x be set;
  assume x in the carrier of S;
  then x in (the carrier of R) \/ (the carrier of S) by XBOOLE_0:def 3;
  hence thesis by Def2;
end;

theorem Th12:
  for R, S being non empty RelStr for x being set st x in (the
  carrier of R) /\ (the carrier of S) holds x is Element of R
proof
  let R, S be non empty RelStr;
  let x be set;
  assume
A1: x in (the carrier of R) /\ (the carrier of S);
  (the carrier of R) /\ (the carrier of S) c= the carrier of R by XBOOLE_1:17;
  hence thesis by A1;
end;

theorem Th13:
  for R, S being non empty RelStr for x being set st x in (the
  carrier of R) /\ (the carrier of S) holds x is Element of S
proof
  let R, S be non empty RelStr;
  let x be set;
  assume
A1: x in (the carrier of R) /\ (the carrier of S);
  (the carrier of R) /\ (the carrier of S) c= the carrier of S by XBOOLE_1:17;
  hence thesis by A1;
end;

theorem
  for R, S being antisymmetric reflexive transitive with_suprema non
empty RelStr for x, y being Element of R [*] S st x in the carrier of R & y in
the carrier of S & R tolerates S holds x <= y iff (ex a being Element of R [*]
  S st a in (the carrier of R) /\ (the carrier of S) & x <= a & a <= y)
proof
  let R, S be antisymmetric reflexive transitive with_suprema non empty
  RelStr, x, y be Element of R [*] S;
  assume that
A1: x in the carrier of R and
A2: y in the carrier of S and
A3: R tolerates S;
  per cases;
  suppose
A4: [x,y] in the InternalRel of R;
    hereby
      assume
A5:   x <= y;
      take a = y;
      y in the carrier of R by A4,ZFMISC_1:87;
      hence a in (the carrier of R) /\ (the carrier of S) by A2,XBOOLE_0:def 4;
      R [*] S is reflexive by Th3;
      hence x <= a & a <= y by A5,ORDERS_2:1;
    end;
    [x,y] in the InternalRel of R [*] S by A4,Th6;
    hence thesis by ORDERS_2:def 5;
  end;
  suppose
A6: [x,y] in the InternalRel of S;
    hereby
      assume
A7:   x <= y;
      take a = x;
      x in the carrier of S by A6,ZFMISC_1:87;
      hence a in (the carrier of R) /\ (the carrier of S) by A1,XBOOLE_0:def 4;
      R [*] S is reflexive by Th3;
      hence x <= a & a <= y by A7,ORDERS_2:1;
    end;
    [x,y] in the InternalRel of R [*] S by A6,Th6;
    hence thesis by ORDERS_2:def 5;
  end;
  suppose that
A8: ( not [x,y] in the InternalRel of R)& not [x,y] in the InternalRel of S;
    hereby
      assume x <= y;
      then [x,y] in the InternalRel of R [*] S by ORDERS_2:def 5;
      then [x,y] in (the InternalRel of R) \/ (the InternalRel of S) \/ (the
      InternalRel of R) * the InternalRel of S by Def2;
      then [x,y] in (the InternalRel of R) \/ (the InternalRel of S) or [x,y]
      in (the InternalRel of R) * the InternalRel of S by XBOOLE_0:def 3;
      then consider z being object such that
A9:   [x,z] in the InternalRel of R and
A10:  [z,y] in the InternalRel of S by A8,RELAT_1:def 8,XBOOLE_0:def 3;
A11:  z in the carrier of R by A9,ZFMISC_1:87;
A12:  z in the carrier of S by A10,ZFMISC_1:87;
      then z in (the carrier of R) \/ (the carrier of S) by XBOOLE_0:def 3;
      then reconsider z as Element of R [*] S by Def2;
      take z;
      thus z in (the carrier of R) /\ (the carrier of S) by A11,A12,
XBOOLE_0:def 4;
      [x,z] in the InternalRel of R [*] S by A9,Th6;
      hence x <= z by ORDERS_2:def 5;
      [z,y] in the InternalRel of R [*] S by A10,Th6;
      hence z <= y by ORDERS_2:def 5;
    end;
    given a being Element of R [*] S such that
A13: a in (the carrier of R) /\ (the carrier of S) and
A14: x <= a and
A15: a <= y;
    reconsider y9 = y, a1 = a as Element of S by A2,A13,Th13;
    a1 <= y9 by A3,A15,Th9;
    then
A16: [a,y] in the InternalRel of S by ORDERS_2:def 5;
    reconsider x9 = x, a9 = a as Element of R by A1,A13,Th12;
    x9 <= a9 by A3,A14,Th8;
    then [x,a] in the InternalRel of R by ORDERS_2:def 5;
    then [x,y] in (the InternalRel of R) * the InternalRel of S by A16,
RELAT_1:def 8;
    then [x,y] in (the InternalRel of R) \/ (the InternalRel of S) \/ (the
    InternalRel of R) * the InternalRel of S by XBOOLE_0:def 3;
    then [x,y] in the InternalRel of R [*] S by Def2;
    hence thesis by ORDERS_2:def 5;
  end;
end;

theorem Th15:
  for R, S being non empty RelStr, a, b being Element of R, c, d
  being Element of S st a = c & b = d & R tolerates S & R is transitive & S is
  transitive holds a <= b iff c <= d
proof
  let R, S be non empty RelStr, a, b be Element of R, c, d be Element of S;
  assume that
A1: a = c & b = d and
A2: R tolerates S and
A3: R is transitive and
A4: S is transitive;
  a in (the carrier of R) \/ the carrier of S & b in (the carrier of R) \/
  the carrier of S by XBOOLE_0:def 3;
  then reconsider a9 = a, b9 = b as Element of R [*] S by Def2;
  hereby
    assume a <= b;
    then a9 <= b9 by A2,A3,Th8;
    hence c <= d by A1,A2,A4,Th9;
  end;
  assume c <= d;
  then a9 <= b9 by A1,A2,A4,Th9;
  hence thesis by A2,A3,Th8;
end;

theorem Th16:
  for R being antisymmetric reflexive transitive with_suprema non
  empty RelStr, D being lower directed Subset of R for x, y being Element of R
  st x in D & y in D holds x "\/" y in D
proof
  let R be antisymmetric reflexive transitive with_suprema non empty RelStr,
  D be lower directed Subset of R;
  let x, y be Element of R;
  assume x in D & y in D;
  then consider z being Element of R such that
A1: z in D and
A2: x <= z & y <= z by WAYBEL_0:def 1;
  x "\/" y <= z by A2,YELLOW_0:22;
  hence thesis by A1,WAYBEL_0:def 19;
end;

theorem Th17:
  for R, S being RelStr, a, b being set st (the carrier of R) /\ (
the carrier of S) is upper Subset of R & [a,b] in the InternalRel of R [*] S &
  a in the carrier of S holds b in the carrier of S
proof
  let R, S be RelStr, a, b be set;
  set X = (the carrier of R) /\ (the carrier of S);
  reconsider X as Subset of R by XBOOLE_1:17;
  assume that
A1: (the carrier of R) /\ (the carrier of S) is upper Subset of R and
A2: [a,b] in the InternalRel of R [*] S and
A3: a in the carrier of S;
  [a,b] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
  InternalRel of R) * the InternalRel of S) by A2,Def2;
  then
A4: [a,b] in (the InternalRel of R) \/ (the InternalRel of S) or [a,b] in ((
  the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
  assume
A5: not b in the carrier of S;
  per cases by A4,XBOOLE_0:def 3;
  suppose
A6: [a,b] in the InternalRel of R;
    then reconsider a9 = a, b9 = b as Element of R by ZFMISC_1:87;
    a in the carrier of R by A6,ZFMISC_1:87;
    then
A7: a in (the carrier of R) /\ the carrier of S by A3,XBOOLE_0:def 4;
    a9 <= b9 by A6,ORDERS_2:def 5;
    then X c= the carrier of S & b in X by A1,A7,WAYBEL_0:def 20,XBOOLE_1:17;
    hence thesis by A5;
  end;
  suppose
    [a,b] in the InternalRel of S;
    hence thesis by A5,ZFMISC_1:87;
  end;
  suppose
    [a,b] in (the InternalRel of R) * the InternalRel of S;
    hence thesis by A5,ZFMISC_1:87;
  end;
end;

theorem Th18: :: theorem 3.1 (xi)
  for R, S being RelStr, a, b being Element of R [*] S st (the
  carrier of R) /\ (the carrier of S) is upper Subset of R & a <= b & a in the
  carrier of S holds b in the carrier of S
proof
  let R, S be RelStr, a, b be Element of R [*] S;
  assume that
A1: (the carrier of R) /\ (the carrier of S) is upper Subset of R and
A2: a <= b and
A3: a in the carrier of S;
  [a,b] in the InternalRel of R [*] S by A2,ORDERS_2:def 5;
  hence thesis by A1,A3,Th17;
end;

theorem :: theorem 3.1 (vi)
  for R, S being antisymmetric reflexive transitive with_suprema non
  empty RelStr for x, y being Element of R, a, b being Element of S st (the
  carrier of R) /\ (the carrier of S) is lower directed Subset of S & (the
carrier of R) /\ (the carrier of S) is upper Subset of R & R tolerates S & x =
  a & y = b holds x "\/" y = a "\/" b
proof
  let R, S be antisymmetric reflexive transitive with_suprema non empty
  RelStr;
  let x, y be Element of R;
  let a, b be Element of S;
  assume that
A1: (the carrier of R) /\ (the carrier of S) is lower directed Subset of S and
A2: (the carrier of R) /\ (the carrier of S) is upper Subset of R and
A3: R tolerates S and
A4: x = a and
A5: y = b;
  a in (the carrier of R) /\ (the carrier of S) & b in (the carrier of R)
  /\ ( the carrier of S) by A4,A5,XBOOLE_0:def 4;
  then reconsider xy = a "\/" b as Element of R by A1,Th13,Th16;
  a "\/" b >= b by YELLOW_0:22;
  then
A6: xy >= y by A3,A5,Th15;
A7: for d being Element of R st d >= x & d >= y holds xy <= d
  proof
    let d be Element of R;
    reconsider X = x, D = d as Element of R [*] S by Th10;
    assume that
A8: d >= x and
A9: d >= y;
    X <= D by A3,A8,Th8;
    then reconsider dd = d as Element of S by A2,A4,Th18;
    dd >= a & b <= dd by A3,A4,A5,A8,A9,Th15;
    then a "\/" b <= dd by YELLOW_5:9;
    hence thesis by A3,Th15;
  end;
  a "\/" b >= a by YELLOW_0:22;
  then xy >= x by A3,A4,Th15;
  hence thesis by A6,A7,YELLOW_0:22;
end;

theorem
  for R, S being lower-bounded antisymmetric reflexive transitive
with_suprema non empty RelStr st (the carrier of R) /\ (the carrier of S) is
  non empty lower directed Subset of S holds Bottom S in the carrier of R
proof
  let R, S be lower-bounded antisymmetric reflexive transitive with_suprema
  non empty RelStr;
  assume
A1: (the carrier of R) /\ (the carrier of S) is non empty lower directed
  Subset of S;
  then consider x being object such that
A2: x in (the carrier of R) /\ (the carrier of S) by XBOOLE_0:def 1;
  reconsider x as Element of S by A2,Th13;
  Bottom S <= x by YELLOW_0:44;
  then Bottom S in (the carrier of R) /\ (the carrier of S) by A1,A2,
WAYBEL_0:def 19;
  hence thesis by XBOOLE_0:def 4;
end;

theorem Th21:
  for R, S being RelStr, a, b being set st (the carrier of R) /\ (
the carrier of S) is lower Subset of S & [a,b] in the InternalRel of R [*] S &
  b in the carrier of R holds a in the carrier of R
proof
  let R, S be RelStr, a, b be set;
  set X = (the carrier of R) /\ (the carrier of S);
  reconsider X as Subset of R by XBOOLE_1:17;
  assume that
A1: (the carrier of R) /\ (the carrier of S) is lower Subset of S and
A2: [a,b] in the InternalRel of R [*] S and
A3: b in the carrier of R;
  [a,b] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
  InternalRel of R) * the InternalRel of S) by A2,Def2;
  then
A4: [a,b] in (the InternalRel of R) \/ (the InternalRel of S) or [a,b] in ((
  the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
  assume
A5: not a in the carrier of R;
  per cases by A4,XBOOLE_0:def 3;
  suppose
A6: [a,b] in the InternalRel of S;
    then reconsider a9 = a, b9 = b as Element of S by ZFMISC_1:87;
    b in the carrier of S by A6,ZFMISC_1:87;
    then
A7: b in (the carrier of R) /\ the carrier of S by A3,XBOOLE_0:def 4;
    a9 <= b9 by A6,ORDERS_2:def 5;
    then a in X by A1,A7,WAYBEL_0:def 19;
    hence thesis by A5;
  end;
  suppose
    [a,b] in the InternalRel of R;
    hence thesis by A5,ZFMISC_1:87;
  end;
  suppose
    [a,b] in (the InternalRel of R) * the InternalRel of S;
    hence thesis by A5,ZFMISC_1:87;
  end;
end;

theorem :: theorem 1 (ix)
  for x, y being set, R, S being RelStr st [x,y] in the InternalRel of R
  [*] S & (the carrier of R) /\ (the carrier of S) is upper Subset of R holds x
in the carrier of R & y in the carrier of R or x in the carrier of S & y in the
  carrier of S or x in (the carrier of R) \ (the carrier of S) & y in (the
  carrier of S) \ (the carrier of R)
proof
  let x, y be set, R, S be RelStr;
  assume that
A1: [x,y] in the InternalRel of R [*] S and
A2: (the carrier of R) /\ (the carrier of S) is upper Subset of R;
  x in the carrier of R [*] S by A1,ZFMISC_1:87;
  then
A3: x in (the carrier of R) \/ (the carrier of S) by Def2;
  y in the carrier of R [*] S by A1,ZFMISC_1:87;
  then
A4: y in (the carrier of R) \/ (the carrier of S) by Def2;
  per cases by A3,A4,XBOOLE_0:def 3;
  suppose
    x in the carrier of R & y in the carrier of R;
    hence thesis;
  end;
  suppose
    x in the carrier of S & y in the carrier of S;
    hence thesis;
  end;
  suppose
    x in the carrier of R & y in the carrier of S;
    hence thesis by XBOOLE_0:def 5;
  end;
  suppose
    x in the carrier of S & y in the carrier of R;
    hence thesis by A1,A2,Th17;
  end;
end;

theorem :: theorem 3.1 (x)
  for R, S being RelStr, a, b being Element of R [*] S st (the carrier
of R) /\ (the carrier of S) is lower Subset of S & a <= b & b in the carrier of
  R holds a in the carrier of R
proof
  let R, S be RelStr, a, b be Element of R [*] S;
  assume that
A1: (the carrier of R) /\ (the carrier of S) is lower Subset of S and
A2: a <= b and
A3: b in the carrier of R;
  [a,b] in the InternalRel of R [*] S by A2,ORDERS_2:def 5;
  hence thesis by A1,A3,Th21;
end;

theorem :: theorem 3.1 (xii)
  for R, S being RelStr st R tolerates S & (the carrier of R) /\ (the
  carrier of S) is upper Subset of R & (the carrier of R) /\ (the carrier of S)
  is lower Subset of S & R is transitive antisymmetric & S is transitive
  antisymmetric holds R [*] S is antisymmetric
proof
  let R, S be RelStr;
  set X = the carrier of R [*] S, F = the InternalRel of R [*] S;
  assume that
A1: R tolerates S and
A2: (the carrier of R) /\ (the carrier of S) is upper Subset of R and
A3: (the carrier of R) /\ (the carrier of S) is lower Subset of S and
A4: R is transitive antisymmetric and
A5: S is transitive antisymmetric;
A6: the InternalRel of S is_antisymmetric_in the carrier of S by A5,
ORDERS_2:def 4;
A7: the InternalRel of R is_antisymmetric_in the carrier of R by A4,
ORDERS_2:def 4;
  F is_antisymmetric_in X
  proof
    let x, y be object;
    assume that
A8: x in X & y in X and
A9: [x,y] in F and
A10: [y,x] in F;
A11: x in (the carrier of R) \/ (the carrier of S) & y in (the carrier of
    R) \/ ( the carrier of S) by A8,Def2;
    per cases by A11,XBOOLE_0:def 3;
    suppose
A12:  x in the carrier of R & y in the carrier of R;
      then
      [x,y] in the InternalRel of R & [y,x] in the InternalRel of R by A1,A4,A9
,A10,Th4;
      hence thesis by A7,A12;
    end;
    suppose
A13:  x in the carrier of R & y in the carrier of S;
      then
A14:  y in the carrier of R by A3,A10,Th21;
      then
      [x,y] in the InternalRel of R & [y,x] in the InternalRel of R by A1,A4,A9
,A10,A13,Th4;
      hence thesis by A7,A13,A14;
    end;
    suppose
A15:  x in the carrier of S & y in the carrier of R;
      then
A16:  y in the carrier of S by A2,A9,Th17;
      then
      [x,y] in the InternalRel of S & [y,x] in the InternalRel of S by A1,A5,A9
,A10,A15,Th5;
      hence thesis by A6,A15,A16;
    end;
    suppose
A17:  x in the carrier of S & y in the carrier of S;
      then
      [x,y] in the InternalRel of S & [y,x] in the InternalRel of S by A1,A5,A9
,A10,Th5;
      hence thesis by A6,A17;
    end;
  end;
  hence thesis by ORDERS_2:def 4;
end;

theorem :: theorem 3.1 (xiii)
  for R, S being RelStr st (the carrier of R) /\ (the carrier of S) is
upper Subset of R & (the carrier of R) /\ (the carrier of S) is lower Subset of
  S & R tolerates S & R is transitive & S is transitive holds R [*] S is
  transitive
proof
  let R, S be RelStr;
  set X = the carrier of R [*] S, F = the InternalRel of R [*] S;
  assume that
A1: (the carrier of R) /\ (the carrier of S) is upper Subset of R and
A2: (the carrier of R) /\ (the carrier of S) is lower Subset of S and
A3: R tolerates S and
A4: R is transitive and
A5: S is transitive;
A6: the InternalRel of S is_transitive_in the carrier of S by A5,ORDERS_2:def 3
;
A7: the InternalRel of R is_transitive_in the carrier of R by A4,ORDERS_2:def 3
;
  F is_transitive_in X
  proof
    let x, y, z be object;
    assume that
A8: x in X & y in X and
A9: z in X and
A10: [x,y] in F and
A11: [y,z] in F;
A12: x in (the carrier of R) \/ (the carrier of S) & y in (the carrier of
    R) \/ ( the carrier of S) by A8,Def2;
A13: z in (the carrier of R) \/ (the carrier of S) by A9,Def2;
    per cases by A12,A13,XBOOLE_0:def 3;
    suppose
A14:  x in the carrier of R & y in the carrier of R & z in the carrier of R;
      then
      [x,y] in the InternalRel of R & [y,z] in the InternalRel of R by A3,A4
,A10,A11,Th4;
      then [x,z] in the InternalRel of R by A7,A14;
      hence thesis by Th6;
    end;
    suppose
A15:  x in the carrier of R & y in the carrier of R & z in the carrier of S;
      then
A16:  [x,y] in the InternalRel of R by A3,A4,A10,Th4;
      [y,z] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
      InternalRel of R) * the InternalRel of S) by A11,Def2;
      then
A17:  [y,z] in (the InternalRel of R) \/ (the InternalRel of S) or [y,z]
      in ((the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
      now
        per cases by A17,XBOOLE_0:def 3;
        suppose
A18:      [y,z] in the InternalRel of R;
          then z in the carrier of R by ZFMISC_1:87;
          then [x,z] in the InternalRel of R by A7,A15,A16,A18;
          hence thesis by Th6;
        end;
        suppose
          [y,z] in the InternalRel of S;
          then
          [x,z] in ((the InternalRel of R) * the InternalRel of S) by A16,
RELAT_1:def 8;
          then
          [x,z] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((
          the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
          hence thesis by Def2;
        end;
        suppose
          [y,z] in ((the InternalRel of R) * the InternalRel of S);
          then consider a being object such that
A19:      [y,a] in the InternalRel of R and
A20:      [a,z] in the InternalRel of S by RELAT_1:def 8;
          a in the carrier of R by A19,ZFMISC_1:87;
          then [x,a] in the InternalRel of R by A7,A15,A16,A19;
          then
          [x,z] in ((the InternalRel of R) * the InternalRel of S) by A20,
RELAT_1:def 8;
          then [x,z] in ((the InternalRel of R) \/ (the InternalRel of S)) \/
          ((the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
          hence thesis by Def2;
        end;
      end;
      hence thesis;
    end;
    suppose
A21:  x in the carrier of R & y in the carrier of S & z in the carrier of R;
      then
A22:  y in the carrier of R by A2,A11,Th21;
      then
      [x,y] in the InternalRel of R & [y,z] in the InternalRel of R by A3,A4
,A10,A11,A21,Th4;
      then [x,z] in the InternalRel of R by A7,A21,A22;
      hence thesis by Th6;
    end;
    suppose
A23:  x in the carrier of S & y in the carrier of R & z in the carrier of R;
      then
A24:  [y,z] in the InternalRel of R by A3,A4,A11,Th4;
A25:  x in the carrier of R by A2,A10,A23,Th21;
      then [x,y] in the InternalRel of R by A3,A4,A10,A23,Th4;
      then [x,z] in the InternalRel of R by A7,A23,A25,A24;
      hence thesis by Th6;
    end;
    suppose
A26:  x in the carrier of S & y in the carrier of S & z in the carrier of R;
      then
A27:  [x,y] in the InternalRel of S by A3,A5,A10,Th5;
A28:  z in the carrier of S by A1,A11,A26,Th17;
      then [y,z] in the InternalRel of S by A3,A5,A11,A26,Th5;
      then [x,z] in the InternalRel of S by A6,A26,A27,A28;
      hence thesis by Th6;
    end;
    suppose
A29:  x in the carrier of S & y in the carrier of S & z in the carrier of S;
      then
      [x,y] in the InternalRel of S & [y,z] in the InternalRel of S by A3,A5
,A10,A11,Th5;
      then [x,z] in the InternalRel of S by A6,A29;
      hence thesis by Th6;
    end;
    suppose
A30:  x in the carrier of R & y in the carrier of S & z in the carrier of S;
      then
A31:  [y,z] in the InternalRel of S by A3,A5,A11,Th5;
      [x,y] in (the InternalRel of R) \/ (the InternalRel of S) \/ ((the
      InternalRel of R) * the InternalRel of S) by A10,Def2;
      then
A32:  [x,y] in (the InternalRel of R) \/ (the InternalRel of S) or [x,y]
      in ((the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
      now
        per cases by A32,XBOOLE_0:def 3;
        suppose
          [x,y] in the InternalRel of R;
          then
          [x,z] in ((the InternalRel of R) * the InternalRel of S) by A31,
RELAT_1:def 8;
          then [x,z] in ((the InternalRel of R) \/ (the InternalRel of S)) \/
          ((the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
          hence thesis by Def2;
        end;
        suppose
A33:      [x,y] in the InternalRel of S;
          then x in the carrier of S by ZFMISC_1:87;
          then [x,z] in the InternalRel of S by A6,A30,A31,A33;
          hence thesis by Th6;
        end;
        suppose
          [x,y] in ((the InternalRel of R) * the InternalRel of S);
          then consider a being object such that
A34:      [x,a] in the InternalRel of R and
A35:      [a,y] in the InternalRel of S by RELAT_1:def 8;
          a in the carrier of S by A35,ZFMISC_1:87;
          then [a,z] in the InternalRel of S by A6,A30,A31,A35;
          then
          [x,z] in ((the InternalRel of R) * the InternalRel of S) by A34,
RELAT_1:def 8;
          then [x,z] in ((the InternalRel of R) \/ (the InternalRel of S)) \/
          ((the InternalRel of R) * the InternalRel of S) by XBOOLE_0:def 3;
          hence thesis by Def2;
        end;
      end;
      hence thesis;
    end;
    suppose
A36:  x in the carrier of S & y in the carrier of R & z in the carrier of S;
      then
A37:  y in the carrier of S by A1,A10,Th17;
      then
      [x,y] in the InternalRel of S & [y,z] in the InternalRel of S by A3,A5
,A10,A11,A36,Th5;
      then [x,z] in the InternalRel of S by A6,A36,A37;
      hence thesis by Th6;
    end;
  end;
  hence thesis by ORDERS_2:def 3;
end;