WAYBEL30

index · ← WAYBEL29 · WAYBEL31 →
:: Meet Continuous Lattices Revisited
::  by Artur Korni{\l}owicz
::
:: Received January 6, 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 XBOOLE_0, TARSKI, SUBSET_1, RELAT_2, ORDERS_2, WAYBEL_0,
      YELLOW_1, CARD_FIL, STRUCT_0, ZFMISC_1, XXREAL_0, LATTICE3, ORDINAL2,
      YELLOW_0, LATTICES, WAYBEL_2, YELLOW_9, WAYBEL11, REWRITE1, WAYBEL_9,
      PRE_TOPC, PROB_1, WAYBEL19, PRELAMB, ORDINAL1, SETFAM_1, CANTOR_1, DIRAF,
      RCOMP_1, FINSET_1, RLVECT_3, COMPTS_1, YELLOW_8, TOPS_1, WAYBEL29,
      YELLOW13, FUNCT_1, WAYBEL21, RELAT_1, PARTFUN1, MCART_1, TOPS_2,
      WAYBEL_3, TDLAT_3, CONNSP_2, EQREL_1, WAYBEL_8, WAYBEL_6, WAYBEL30,
      CARD_1;
 notations TARSKI, XBOOLE_0, ZFMISC_1, SUBSET_1, RELAT_1, FUNCT_1, RELSET_1,
      PARTFUN1, BINOP_1, FUNCT_3, SETFAM_1, DOMAIN_1, CARD_1, STRUCT_0,
      FINSET_1, ORDERS_2, PRE_TOPC, TOPS_1, TOPS_2, COMPTS_1, CONNSP_2,
      TDLAT_3, LATTICE3, BORSUK_1, CANTOR_1, YELLOW_0, WAYBEL_0, YELLOW_1,
      WAYBEL_1, YELLOW_3, YELLOW_4, WAYBEL_2, WAYBEL_3, YELLOW_8, WAYBEL_6,
      WAYBEL_8, WAYBEL_9, WAYBEL11, YELLOW_9, WAYBEL19, WAYBEL21, YELLOW13,
      WAYBEL29;
 constructors TOPS_1, TOPS_2, TDLAT_3, CANTOR_1, ORDERS_3, WAYBEL_1, YELLOW_4,
      WAYBEL_6, WAYBEL_8, YELLOW_8, WAYBEL19, WAYBEL21, YELLOW13, WAYBEL29,
      COMPTS_1, WAYBEL_2;
 registrations XBOOLE_0, SUBSET_1, RELSET_1, FINSET_1, STRUCT_0, TOPS_1,
      BORSUK_1, LATTICE3, YELLOW_0, TEX_1, WAYBEL_0, YELLOW_1, YELLOW_2,
      YELLOW_3, YELLOW_4, WAYBEL_2, WAYBEL_3, WAYBEL_4, YELLOW_6, WAYBEL_8,
      WAYBEL10, WAYBEL11, WAYBEL14, YELLOW_9, YELLOW12, WAYBEL19, YELLOW13,
      PRE_TOPC, CARD_1;
 requirements BOOLE, SUBSET;
 definitions TARSKI, PRE_TOPC, LATTICE3, YELLOW_0, WAYBEL_0, WAYBEL_2,
      WAYBEL_3, YELLOW_8, WAYBEL19, WAYBEL11, YELLOW13, XBOOLE_0, TOPS_2;
 equalities LATTICE3, WAYBEL_0, WAYBEL_3, WAYBEL11, BINOP_1, STRUCT_0;
 expansions TARSKI, PRE_TOPC, LATTICE3, YELLOW_0, WAYBEL_0, WAYBEL_3, WAYBEL11,
      YELLOW13, XBOOLE_0;
 theorems TARSKI, PRE_TOPC, ORDERS_2, TOPS_1, TOPS_2, BORSUK_1, CONNSP_2,
      TDLAT_3, COMPTS_1, RELAT_1, ZFMISC_1, FUNCT_1, FUNCT_2, FUNCT_3,
      YELLOW_0, YELLOW_1, YELLOW_2, YELLOW_3, YELLOW_4, YELLOW_8, WAYBEL_0,
      WAYBEL_2, WAYBEL_3, WAYBEL_8, YELLOW13, WAYBEL11, WAYBEL12, WAYBEL14,
      YELLOW_9, WAYBEL19, YELLOW12, WAYBEL21, WAYBEL29, SETFAM_1, XBOOLE_0,
      XBOOLE_1, STRUCT_0;
 schemes SUBSET_1, FINSET_1, DOMAIN_1;

begin

theorem Th1:
  for x being set, D being non empty set holds x /\ union D = union
  the set of all x /\ d where d is Element of D
proof
  let x be set, D be non empty set;
  hereby
    let a be object;
    assume
A1: a in x /\ union D;
    then a in union D by XBOOLE_0:def 4;
    then consider Z being set such that
A2: a in Z and
A3: Z in D by TARSKI:def 4;
A4: x /\ Z in the set of all x /\ d where d is Element of D by A3;
    a in x by A1,XBOOLE_0:def 4;
    then a in x /\ Z by A2,XBOOLE_0:def 4;
    hence
    a in union the set of all x /\ d where d is Element of D by A4,
TARSKI:def 4;
  end;
  let a be object;
  assume a in union the set of all x /\ d where d is Element of D;
  then consider Z being set such that
A5: a in Z and
A6: Z in the set of all x /\ d where d is Element of D by TARSKI:def 4;
  consider d being Element of D such that
A7: Z = x /\ d and
  not contradiction by A6;
  a in d by A5,A7,XBOOLE_0:def 4;
  then
A8: a in union D by TARSKI:def 4;
  a in x by A5,A7,XBOOLE_0:def 4;
  hence thesis by A8,XBOOLE_0:def 4;
end;

theorem Th2:
  for R being non empty reflexive transitive RelStr, D being non
  empty directed Subset of InclPoset Ids R holds union D is Ideal of R
proof
  let R be non empty reflexive transitive RelStr, D be non empty directed
  Subset of InclPoset Ids R;
  set d = the Element of D;
  D c= the carrier of InclPoset Ids R;
  then
A1: D c= Ids R by YELLOW_1:1;
A2: D c= bool the carrier of R
  proof
    let d be object;
    assume d in D;
    then d in Ids R by A1;
    then ex I being Ideal of R st d = I;
    hence thesis;
  end;
  d in Ids R by A1;
  then consider I being Ideal of R such that
A3: d = I and
  not contradiction;
A4: for X being Subset of R st X in D holds X is directed
  proof
    let X be Subset of R;
    assume X in D;
    then X in Ids R by A1;
    then ex I being Ideal of R st X = I;
    hence thesis;
  end;
A5: for X, Y being Subset of R st X in D & Y in D ex Z being Subset of R st
  Z in D & X \/ Y c= Z
  proof
    let X, Y be Subset of R;
    assume that
A6: X in D and
A7: Y in D;
    reconsider X1 = X, Y1 = Y as Element of InclPoset Ids R by A6,A7;
    consider Z1 being Element of InclPoset Ids R such that
A8: Z1 in D and
A9: X1 <= Z1 and
A10: Y1 <= Z1 by A6,A7,WAYBEL_0:def 1;
    Z1 in Ids R by A1,A8;
    then ex I being Ideal of R st Z1 = I;
    then reconsider Z = Z1 as Subset of R;
    take Z;
    thus Z in D by A8;
A11: Y1 c= Z1 by A10,YELLOW_1:3;
    X1 c= Z1 by A9,YELLOW_1:3;
    hence thesis by A11,XBOOLE_1:8;
  end;
A12: for X being Subset of R st X in D holds X is lower
  proof
    let X be Subset of R;
    assume X in D;
    then X in Ids R by A1;
    then ex I being Ideal of R st X = I;
    hence thesis;
  end;
  set i = the Element of I;
  i in d by A3;
  hence thesis by A12,A2,A4,A5,TARSKI:def 4,WAYBEL_0:26,46;
end;

Lm1: now
  let R be non empty reflexive transitive RelStr, D be non empty directed
  Subset of InclPoset Ids R, UD be Element of InclPoset Ids R such that
A1: UD = union D;
  thus D is_<=_than UD
  proof
    let d be Element of InclPoset Ids R;
    assume
A2: d in D;
    d c= UD
    by A1,A2,TARSKI:def 4;
    hence d <= UD by YELLOW_1:3;
  end;
end;

Lm2: now
  let R be non empty reflexive transitive RelStr, D be non empty directed
  Subset of InclPoset Ids R, UD be Element of InclPoset Ids R such that
A1: UD = union D;
  thus for b being Element of InclPoset Ids R st b is_>=_than D holds UD <= b
  proof
    let b be Element of InclPoset Ids R such that
A2: for a being Element of InclPoset Ids R st a in D holds b >= a;
    UD c= b
    proof
      let x be object;
      assume x in UD;
      then consider Z being set such that
A3:   x in Z and
A4:   Z in D by A1,TARSKI:def 4;
      reconsider Z as Element of InclPoset Ids R by A4;
      b >= Z by A2,A4;
      then Z c= b by YELLOW_1:3;
      hence thesis by A3;
    end;
    hence thesis by YELLOW_1:3;
  end;
end;

:: Exercise 2.16 (i), p. 16

registration
  let R be non empty reflexive transitive RelStr;
  cluster InclPoset Ids R -> up-complete;
  coherence
  proof
    set I = InclPoset Ids R;
    let D be non empty directed Subset of I;
    reconsider UD = union D as Ideal of R by Th2;
    UD in Ids R;
    then reconsider UD as Element of I by YELLOW_1:1;
    take UD;
    thus thesis by Lm1,Lm2;
  end;
end;

theorem Th3:
  for R being non empty reflexive transitive RelStr, D being non
  empty directed Subset of InclPoset Ids R holds sup D = union D
proof
  let R be non empty reflexive transitive RelStr, D be non empty directed
  Subset of InclPoset Ids R;
  reconsider UD = union D as Ideal of R by Th2;
A1: ex_sup_of D,InclPoset Ids R by WAYBEL_0:75;
  UD in Ids R;
  then reconsider UD as Element of InclPoset Ids R by YELLOW_1:1;
A2: for b being Element of InclPoset Ids R st b is_>=_than D holds UD <= b
  by Lm2;
  D is_<=_than UD by Lm1;
  hence thesis by A2,A1,YELLOW_0:def 9;
end;

theorem Th4:
  for R being Semilattice, D being non empty directed Subset of
  InclPoset Ids R, x being Element of InclPoset Ids R holds sup ({x} "/\" D) =
  union the set of all x /\ d where d is Element of D
proof
  let R be Semilattice, D be non empty directed Subset of InclPoset Ids R, x
  be Element of InclPoset Ids R;
  set I = InclPoset Ids R, A = the set of all x /\ d where d is Element of D;
  set xD = {x "/\" d where d is Element of I: d in D};
  xD c= the carrier of I
  proof
    let a be object;
    assume a in xD;
    then ex d being Element of I st a = x "/\" d & d in D;
    hence thesis;
  end;
  then reconsider xD as Subset of I;
A1: ex_sup_of {x} "/\" D,I by WAYBEL_2:1;
  then ex_sup_of xD,I by YELLOW_4:42;
  then
A2: sup xD is_>=_than xD by YELLOW_0:def 9;
  hereby
    set A = the set of all x /\ w where w is Element of D;
    let a be object;
    ex_sup_of D,I by WAYBEL_0:75;
    then sup ({x} "/\" D) <= x "/\" sup D by A1,YELLOW_4:53;
    then
A3: sup ({x} "/\" D) c= x "/\" sup D by YELLOW_1:3;
    assume a in sup ({x} "/\" D);
    then a in x "/\" sup D by A3;
    then
A4: a in x /\ sup D by YELLOW_2:43;
    then a in sup D by XBOOLE_0:def 4;
    then a in union D by Th3;
    then consider d being set such that
A5: a in d and
A6: d in D by TARSKI:def 4;
    reconsider d as Element of I by A6;
A7: x /\ d in A by A6;
    a in x by A4,XBOOLE_0:def 4;
    then a in x /\ d by A5,XBOOLE_0:def 4;
    hence a in union A by A7,TARSKI:def 4;
  end;
  let a be object;
  assume a in union A;
  then consider Z being set such that
A8: a in Z and
A9: Z in A by TARSKI:def 4;
  consider d being Element of D such that
A10: Z = x /\ d and
  not contradiction by A9;
  reconsider d as Element of I;
A11: xD = {x} "/\" D by YELLOW_4:42;
  then x "/\" d in {x} "/\" D;
  then sup xD >= x "/\" d by A2,A11;
  then
A12: x "/\" d c= sup xD by YELLOW_1:3;
  x /\ d = x "/\" d by YELLOW_2:43;
  then a in sup xD by A12,A8,A10;
  hence thesis by YELLOW_4:42;
end;

:: Exercise 4.8 (i), p. 33

registration
  let R be Semilattice;
  cluster InclPoset Ids R -> satisfying_MC;
  coherence
  proof
    set I = InclPoset Ids R;
    let x be Element of I, D be non empty directed Subset of I;
    thus x "/\" sup D = x /\ sup D by YELLOW_2:43
      .= x /\ union D by Th3
      .= union the set of all x /\ d where d is Element of D by Th1
      .= sup ({x} "/\" D) by Th4;
  end;
end;

registration
  let R be 1-element RelStr;
  cluster -> trivial for TopAugmentation of R;
  coherence
  proof
    let T be TopAugmentation of R;
    the RelStr of T = the RelStr of R by YELLOW_9:def 4;
    hence thesis;
  end;
end;

theorem
  for S being Scott complete TopLattice, T being complete LATTICE, A
being Scott TopAugmentation of T st the RelStr of S = the RelStr of T holds the
  TopRelStr of A = the TopRelStr of S
proof
  let S be Scott complete TopLattice, T be complete LATTICE, A be Scott
  TopAugmentation of T such that
A1: the RelStr of S = the RelStr of T;
A2: the topology of S = sigma S by WAYBEL14:23
    .= sigma T by A1,YELLOW_9:52
    .= the topology of A by YELLOW_9:51;
  the RelStr of A = the RelStr of S by A1,YELLOW_9:def 4;
  hence thesis by A2;
end;

theorem
  for N being Lawson complete TopLattice, T being complete LATTICE, A
being Lawson correct TopAugmentation of T st the RelStr of N = the RelStr of T
  holds the TopRelStr of A = the TopRelStr of N
proof
  let N be Lawson complete TopLattice, T be complete LATTICE, A be Lawson
  correct TopAugmentation of T such that
A1: the RelStr of N = the RelStr of T;
A2: omega T = omega N by A1,WAYBEL19:3;
  set S = the Scott correct TopAugmentation of T;
  set l = the lower correct TopAugmentation of T;
A3: the RelStr of l = the RelStr of T by YELLOW_9:def 4;
A4: the RelStr of S = the RelStr of T by YELLOW_9:def 4;
  (the topology of S) \/ (the topology of l) c= bool the carrier of N
  proof
    let a be object;
    assume a in (the topology of S) \/ (the topology of l);
    then a in the topology of S or a in the topology of l by XBOOLE_0:def 3;
    hence thesis by A1,A4,A3;
  end;
  then reconsider
  X = (the topology of S) \/ (the topology of l) as Subset-Family
  of N;
  reconsider X as Subset-Family of N;
A5: the topology of l = omega T by WAYBEL19:def 2;
  (sigma N) \/ (omega N) is prebasis of N by WAYBEL19:def 3;
  then
A6: (sigma T) \/ (omega N) is prebasis of N by A1,YELLOW_9:52;
A7: the topology of S = sigma T by YELLOW_9:51;
  the carrier of N = (the carrier of S) \/ (the carrier of l) by A1,A4,A3;
  then N is Refinement of S, l by A2,A6,A5,A7,YELLOW_9:def 6;
  then
A8: the topology of N = UniCl FinMeetCl X by YELLOW_9:56
    .= lambda T by A1,A5,A7,WAYBEL19:33
    .= the topology of A by WAYBEL19:def 4;
  the RelStr of A = the RelStr of N by A1,YELLOW_9:def 4;
  hence thesis by A8;
end;

theorem
  for N being Lawson complete TopLattice for S being Scott
TopAugmentation of N for A being Subset of N, J being Subset of S st A = J & J
  is closed holds A is closed
proof
  let N be Lawson complete TopLattice, S be Scott TopAugmentation of N, A be
  Subset of N, J be Subset of S such that
A1: A = J;
  assume J is closed;
  then
A2: [#]S \ J is open;
A3: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  then N is Lawson correct TopAugmentation of S by YELLOW_9:def 4;
  hence [#]N \ A is open by A1,A3,A2,WAYBEL19:37;
end;

registration
  let A be complete LATTICE;
  cluster lambda A -> non empty;
  coherence
  proof
    set S = the Lawson correct TopAugmentation of A;
    InclPoset the topology of S is non trivial;
    hence thesis by WAYBEL19:def 4;
  end;
end;

registration
  let S be Scott complete TopLattice;
  cluster InclPoset sigma S -> complete non trivial;
  coherence;
end;

registration
  let N be Lawson complete TopLattice;
  cluster InclPoset sigma N -> complete non trivial;
  coherence;
  cluster InclPoset lambda N -> complete non trivial;
  coherence
  proof
    set S = the Lawson correct TopAugmentation of N;
    InclPoset the topology of S is complete non trivial;
    hence thesis by WAYBEL19:def 4;
  end;
end;

theorem Th8:
  for T being non empty reflexive RelStr holds sigma T c= {W\
  uparrow F where W, F is Subset of T: W in sigma T & F is finite}
proof
  let T be non empty reflexive RelStr;
  let s be object;
   reconsider ss=s as set by TARSKI:1;
A1: ss\uparrow {}T = s;
  assume s in sigma T;
  hence thesis by A1;
end;

theorem Th9:
  for N being Lawson complete TopLattice holds lambda N = the topology of N
proof
  let N be Lawson complete TopLattice;
  N is Lawson correct TopAugmentation of N by YELLOW_9:44;
  hence thesis by WAYBEL19:def 4;
end;

theorem Th10:
  for N being Lawson complete TopLattice holds sigma N c= lambda N
proof
  let N be Lawson complete TopLattice;
  set Z = {W\uparrow F where W, F is Subset of N: W in sigma N & F is finite};
  Z is Basis of N by WAYBEL19:32;
  then Z c= the topology of N by TOPS_2:64;
  then
A1: Z c= lambda N by Th9;
  sigma N c= Z by Th8;
  hence thesis by A1;
end;

theorem
  for M, N being complete LATTICE st the RelStr of M = the RelStr of N
  holds lambda M = lambda N
proof
  let M, N be complete LATTICE such that
A1: the RelStr of M = the RelStr of N;
A2: lambda N = UniCl FinMeetCl ((sigma N) \/ (omega N)) by WAYBEL19:33;
A3: lambda M = UniCl FinMeetCl ((sigma M) \/ (omega M)) by WAYBEL19:33;
  sigma M = sigma N by A1,YELLOW_9:52;
  hence thesis by A1,A3,A2,WAYBEL19:3;
end;

theorem Th12:
  for N being Lawson complete TopLattice, X being Subset of N
  holds X in lambda N iff X is open
by Th9;

registration
  cluster TopSpace-like -> Scott for reflexive 1-element TopRelStr;
  coherence
  by TDLAT_3:15;
end;

registration
  cluster trivial -> Lawson for complete TopLattice;
  coherence
  proof
    let T be complete TopLattice;
    assume T is trivial;
     then
  the carrier of T is 1-element;
    then reconsider W = T as 1-element complete TopLattice
        by STRUCT_0:def 19;
    set N = the Lawson correct TopAugmentation of W;
A1: the RelStr of T = the RelStr of N by YELLOW_9:def 4;
    the topology of W = {{}, the carrier of W} by TDLAT_3:def 2;
    then the topology of T = the topology of N by A1,TDLAT_3:def 2
      .= lambda T by WAYBEL19:def 4
      .= UniCl FinMeetCl ((sigma T) \/ (omega T)) by WAYBEL19:33;
    then FinMeetCl ((omega T) \/ (sigma T)) is Basis of T by YELLOW_9:22;
    hence (omega T) \/ (sigma T) is prebasis of T by YELLOW_9:23;
  end;
end;

registration
  cluster strict continuous lower-bounded meet-continuous Scott for complete
    TopLattice;
  existence
  proof
    set A = the strict 1-element TopLattice;
    take A;
    thus thesis;
  end;
end;

registration
  cluster strict continuous compact Hausdorff Lawson for complete TopLattice;
  existence
  proof
    set R = the strict trivial complete TopLattice;
    take R;
    thus thesis;
  end;
end;

scheme
  EmptySch { A() -> Scott TopLattice, X() -> set, F(set) -> set }: { F(w)
  where w is Element of A(): w in {} } = {} proof
  thus { F(w) where w is Element of A(): w in {} } c= {}
  proof
    let a be object;
    assume a in { F(w) where w is Element of A(): w in {} };
    then
A1: ex w being Element of A() st a = F(w) & w in {};
    assume not a in {};
    thus thesis by A1;
  end;
  thus thesis;
end;

theorem Th13:
  for N being meet-continuous LATTICE, A being Subset of N st A is
  property(S) holds uparrow A is property(S)
proof
  let N be meet-continuous LATTICE, A be Subset of N such that
A1: for D being non empty directed Subset of N st sup D in A ex y being
Element of N st y in D & for x being Element of N st x in D & x >= y holds x in
  A;
  let D be non empty directed Subset of N;
  assume sup D in uparrow A;
  then consider a being Element of N such that
A2: a <= sup D and
A3: a in A by WAYBEL_0:def 16;
  reconsider aa = {a} as non empty directed Subset of N by WAYBEL_0:5;
  a = sup ({a} "/\" D) by A2,WAYBEL_2:52;
  then consider y being Element of N such that
A4: y in aa "/\" D and
A5: for x being Element of N st x in aa "/\" D & x >= y holds x in A by A1,A3;
  aa "/\" D = {a "/\" d where d is Element of N: d in D} by YELLOW_4:42;
  then consider d being Element of N such that
A6: y = a "/\" d and
A7: d in D by A4;
  take d;
  thus d in D by A7;
  let x be Element of N such that
  x in D and
A8: x >= d;
  d >= y by A6,YELLOW_0:23;
  then
A9: x >= y by A8,ORDERS_2:3;
  y in A by A4,A5,ORDERS_2:1;
  hence thesis by A9,WAYBEL_0:def 16;
end;

registration
  let N be meet-continuous LATTICE, A be property(S) Subset of N;
  cluster uparrow A -> property(S);
  coherence by Th13;
end;

:: Proposition 2.1 (i), p. 153

theorem Th14:
  for N being meet-continuous Lawson complete TopLattice, S
  being Scott TopAugmentation of N, A being Subset of N st A in lambda N holds
  uparrow A in sigma S
proof
  let N be meet-continuous Lawson complete TopLattice, S be Scott
  TopAugmentation of N, A be Subset of N;
  assume A in lambda N;
  then
A1: A is open by Th12;
A2: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  then reconsider Y = A as Subset of S;
A3: S is meet-continuous by A2,YELLOW12:14;
  reconsider UA = uparrow A as Subset of S by A2;
A4: uparrow A = uparrow Y by A2,WAYBEL_0:13;
  Y is property(S) by A1,A2,WAYBEL19:36,YELLOW12:19;
  then UA is open by A3,A4,WAYBEL11:15;
  then uparrow A in the topology of S;
  hence thesis by WAYBEL14:23;
end;

theorem Th15:
  for N being meet-continuous Lawson complete TopLattice for S
  being Scott TopAugmentation of N for A being Subset of N, J being Subset of S
  st A = J holds A is open implies uparrow J is open
proof
  let N be meet-continuous Lawson complete TopLattice, S be Scott
  TopAugmentation of N, A be Subset of N, J be Subset of S such that
A1: A = J;
  assume A is open;
  then A in lambda N by Th12;
  then
A2: uparrow A in sigma S by Th14;
  the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  then uparrow J in sigma S by A2,A1,WAYBEL_0:13;
  hence thesis by WAYBEL14:24;
end;

theorem Th16:
  for N being meet-continuous Lawson complete TopLattice for S
being Scott TopAugmentation of N for x being Point of S, y being Point of N for
J being Basis of y st x = y holds {uparrow A where A is Subset of N: A in J} is
  Basis of x
proof
  let N be meet-continuous Lawson complete TopLattice, S be Scott
  TopAugmentation of N, x be Point of S, y be Point of N, J be Basis of y such
  that
A1: x = y;
  set Z = {uparrow A where A is Subset of N: A in J};
  set K = Z;
A2: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  K c= bool the carrier of S
  proof
    let k be object;
    assume k in K;
    then ex A being Subset of N st k = uparrow A & A in J;
    hence thesis by A2;
  end;
  then reconsider K as Subset-Family of S;
  K is Basis of x
  proof
A3:  K is open
    proof
      let k be Subset of S;
      assume k in K;
      then consider A being Subset of N such that
A4:   k = uparrow A and
A5:   A in J;
      reconsider A9 = A as Subset of S by A2;
      uparrow A9 is open by A5,Th15,YELLOW_8:12;
      then uparrow A9 in the topology of S;
      then uparrow A in the topology of S by A2,WAYBEL_0:13;
      hence thesis by A4;
    end;
    K is x-quasi_basis
    proof
    for k being set st k in K holds x in k
    proof
      let k be set;
      assume k in K;
      then consider A being Subset of N such that
A6:   k = uparrow A and
A7:   A in J;
A8:   A c= uparrow A by WAYBEL_0:16;
      y in Intersect J by YELLOW_8:def 1;
      then y in A by A7,SETFAM_1:43;
      hence thesis by A8,A1,A6;
    end;
    hence x in Intersect K by SETFAM_1:43;
    let sA be Subset of S such that
A9: sA is open and
A10: x in sA;
    sA is upper by A9,WAYBEL11:def 4;
    then
A11: uparrow sA c= sA by WAYBEL_0:24;
    reconsider lA = sA as Subset of N by A2;
    N is Lawson correct TopAugmentation of S by A2,YELLOW_9:def 4;
    then lA is open by A9,WAYBEL19:37;
    then lA in lambda N by Th12;
    then
A12: uparrow lA in sigma S by Th14;
A13: lA c= uparrow lA by WAYBEL_0:16;
    sigma N c= lambda N by Th10;
    then sigma S c= lambda N by A2,YELLOW_9:52;
    then uparrow lA is open by A12,Th12;
    then consider lV1 being Subset of N such that
A14: lV1 in J and
A15: lV1 c= uparrow lA by A13,A1,A10,YELLOW_8:def 1;
    reconsider sUV = uparrow lV1 as Subset of S by A2;
    take sUV;
    thus sUV in K by A14;
A16: lV1 is_coarser_than uparrow lA by A15,WAYBEL12:16;
    sA c= uparrow sA by WAYBEL_0:16;
    then
A17: sA = uparrow sA by A11;
    uparrow sA = uparrow lA by A2,WAYBEL_0:13;
    hence thesis by A16,A17,YELLOW12:28;
  end;
  hence thesis by A3;
  end;
  hence thesis;
end;

:: Proposition 2.1 (ii), p. 153

theorem Th17:
  for N being meet-continuous Lawson complete TopLattice for S
being Scott TopAugmentation of N for X being upper Subset of N, Y being Subset
  of S st X = Y holds Int X = Int Y
proof
  let N be meet-continuous Lawson complete TopLattice, S be Scott
  TopAugmentation of N, X be upper Subset of N, Y be Subset of S such that
A1: X = Y;
A2: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  then reconsider K = uparrow Int X as Subset of S;
  reconsider sX = Int X as Subset of S by A2;
A3: K c= Y
  proof
    let a be object;
A4: Int X c= X by TOPS_1:16;
    assume
A5: a in K;
    then reconsider x = a as Element of N;
A6: X c= uparrow X by WAYBEL_0:16;
    uparrow X c= X by WAYBEL_0:24;
    then
A7: uparrow X = X by A6;
    ex y being Element of N st y <= x & y in Int X by A5,WAYBEL_0:def 16;
    hence thesis by A7,A1,A4,WAYBEL_0:def 16;
  end;
A8: Int X c= uparrow Int X by WAYBEL_0:16;
  uparrow sX is open by Th15;
  then K is open by A2,WAYBEL_0:13;
  then uparrow Int X c= Int Y by A3,TOPS_1:24;
  hence Int X c= Int Y by A8;
  reconsider A = Int Y as Subset of N by A2;
  N is Lawson correct TopAugmentation of S by A2,YELLOW_9:def 4;
  then A is open by WAYBEL19:37;
  hence thesis by A1,TOPS_1:16,24;
end;

:: Proposition 2.1 (iii), p. 153

theorem
  for N being meet-continuous Lawson complete TopLattice for S being
  Scott TopAugmentation of N for X being lower Subset of N, Y being Subset of S
  st X = Y holds Cl X = Cl Y
proof
  let N be meet-continuous Lawson complete TopLattice, S be Scott
  TopAugmentation of N, X be lower Subset of N, Y be Subset of S such that
A1: X = Y;
A2: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  then reconsider A = Cl Y as Subset of N;
  (Cl X)` = (Cl X``)` .= Int X` by TOPS_1:def 1
    .= Int Y` by A1,A2,Th17
    .= (Cl Y``)` by TOPS_1:def 1
    .= A` by A2;
  hence thesis by TOPS_1:1;
end;

theorem Th19:
  for M, N being complete LATTICE, LM being Lawson correct
TopAugmentation of M, LN being Lawson correct TopAugmentation of N st InclPoset
sigma N is continuous holds the topology of [:LM,LN qua TopSpace:] = lambda [:M
  ,N:]
proof
  let M, N be complete LATTICE, LM be Lawson correct TopAugmentation of M, LN
  be Lawson correct TopAugmentation of N such that
A1: InclPoset sigma N is continuous;
  set SMN = the non empty Scott correct TopAugmentation of [:M,N:];
  set lMN = the non empty lower correct TopAugmentation of [:M,N:];
  set LMN = the non empty Lawson correct TopAugmentation of [:M,N:];
A2: [:LM,LN qua TopSpace:] = the TopStruct of LMN
  proof
    set lN = the non empty lower correct TopAugmentation of N;
    set lM = the non empty lower correct TopAugmentation of M;
    set SN = the non empty Scott correct TopAugmentation of N;
    set SM = the non empty Scott correct TopAugmentation of M;
A3: LN is Refinement of SN, lN by WAYBEL19:29;
A4: the RelStr of lN = the RelStr of N by YELLOW_9:def 4;
    (omega LMN) \/ (sigma LMN) is prebasis of LMN by WAYBEL19:def 3;
    then
A5: (omega LMN) \/ (sigma LMN) is prebasis of the TopStruct of LMN by
YELLOW12:33;
A6: the RelStr of LM = the RelStr of M by YELLOW_9:def 4;
A7: the RelStr of LN = the RelStr of N by YELLOW_9:def 4;
A8: the RelStr of LMN = the RelStr of [:M,N:] by YELLOW_9:def 4;
A9: the carrier of [:LM,LN qua TopSpace:] = [:the carrier of LM,the
    carrier of LN:] by BORSUK_1:def 2
      .= the carrier of LMN by A6,A7,A8,YELLOW_3:def 2;
A10: the topology of [:lM,lN qua TopSpace:] = omega [:M,N:] by WAYBEL19:15
      .= omega LMN by A8,WAYBEL19:3;
A11: the RelStr of SN = the RelStr of N by YELLOW_9:def 4;
    the RelStr of SM = the RelStr of M by YELLOW_9:def 4
      .= the RelStr of Sigma M by YELLOW_9:def 4;
    then
A12: the TopStruct of SM = the TopStruct of Sigma M by WAYBEL29:13;
A13: the RelStr of lM = the RelStr of M by YELLOW_9:def 4;
    the RelStr of SN = the RelStr of N by YELLOW_9:def 4
      .= the RelStr of Sigma N by YELLOW_9:def 4;
    then the TopStruct of SN = the TopStruct of Sigma N by WAYBEL29:13;
    then
A14: the topology of [:SM,SN qua TopSpace:] = the topology of [:Sigma M,(
    Sigma N) qua TopSpace:] by A12,WAYBEL29:7
      .= sigma [:M,N:] by A1,WAYBEL29:30
      .= sigma LMN by A8,YELLOW_9:52;
A15: the RelStr of SM = the RelStr of M by YELLOW_9:def 4;
A16: LM is Refinement of SM, lM by WAYBEL19:29;
    then
    [:LM,LN qua TopSpace:] is Refinement of [:SM,SN qua TopSpace:], [:lM,
    lN qua TopSpace:] by A3,A15,A11,A13,A4,YELLOW12:50;
    then the carrier of the TopStruct of LMN = (the carrier of [:SM,SN qua
    TopSpace:]) \/ (the carrier of [:lM,lN qua TopSpace:]) by A9,YELLOW_9:def 6
;
    then
    the TopStruct of LMN is Refinement of [:SM,SN qua TopSpace:], [:lM,lN
    qua TopSpace:] by A5,A14,A10,YELLOW_9:def 6;
    hence thesis by A16,A3,A15,A11,A13,A4,A9,YELLOW12:49;
  end;
  LMN is Refinement of SMN, lMN by WAYBEL19:29;
  then reconsider R = [:LM,LN qua TopSpace:] as Refinement of SMN, lMN by A2,
YELLOW12:47;
  the topology of [:LM,LN qua TopSpace:] = the topology of R;
  hence thesis by WAYBEL19:34;
end;

:: Proposition 2.2, p. 153

theorem Th20:
  for M, N being complete LATTICE, P being Lawson correct
  TopAugmentation of [:M,N:], Q being Lawson correct TopAugmentation of M, R
  being Lawson correct TopAugmentation of N st InclPoset sigma N is continuous
  holds the TopStruct of P = [:Q,R qua TopSpace:]
proof
  let M, N be complete LATTICE, P be Lawson correct TopAugmentation of [:M,N:]
, Q be Lawson correct TopAugmentation of M, R be Lawson correct TopAugmentation
  of N such that
A1: InclPoset sigma N is continuous;
A2: the topology of P = lambda [:M,N:] by WAYBEL19:def 4
    .= the topology of [:Q,R qua TopSpace:] by A1,Th19;
A3: the RelStr of Q = the RelStr of M by YELLOW_9:def 4;
A4: the RelStr of R = the RelStr of N by YELLOW_9:def 4;
  the RelStr of P = the RelStr of [:M,N:] by YELLOW_9:def 4;
  then the carrier of P = [:the carrier of Q, the carrier of N:] by A3,
YELLOW_3:def 2
    .= the carrier of [:Q,R qua TopSpace:] by A4,BORSUK_1:def 2;
  hence thesis by A2;
end;

:: Theorem 2.3, p. 153, first conjunct

theorem Th21:
  for N being meet-continuous Lawson complete TopLattice, x
  being Element of N holds x"/\" is continuous
proof
  let N be meet-continuous Lawson complete TopLattice, x be Element of N;
  for X being non empty Subset of N holds x"/\" preserves_inf_of X by
YELLOW13:11;
  hence thesis by WAYBEL21:45;
end;

registration
  let N be meet-continuous Lawson complete TopLattice, x be Element of N;
  cluster x"/\" -> continuous;
  coherence by Th21;
end;

:: Theorem 2.3, p. 153, second conjunct

theorem Th22:
  for N being meet-continuous Lawson complete TopLattice st
  InclPoset sigma N is continuous holds N is topological_semilattice
proof
  let N be meet-continuous Lawson complete TopLattice such that
A1: InclPoset sigma N is continuous;
  set NN = the Lawson correct TopAugmentation of [:N,N:];
  N is TopAugmentation of N by YELLOW_9:44;
  then
A2: the TopStruct of NN = [:N,N qua TopSpace:] by A1,Th20;
A3: the RelStr of NN = the RelStr of [:N,N:] by YELLOW_9:def 4;
  then reconsider h = inf_op N as Function of NN, N;
A4: the RelStr of N = the RelStr of N;
A5: h is directed-sups-preserving
  proof
    let X be Subset of NN;
    assume X is non empty directed;
    then reconsider X1 = X as non empty directed Subset of [:N,N:] by A3,
WAYBEL_0:3;
    inf_op N preserves_sup_of X1 by WAYBEL_0:def 37;
    hence thesis by A3,A4,WAYBEL_0:65;
  end;
A6: h is infs-preserving
  by A3,WAYBEL_0:def 32,A4,WAYBEL_0:65;
  then h is SemilatticeHomomorphism of NN, N by WAYBEL21:5;
  then
A7: h is continuous by A5,A6,WAYBEL21:46;
A8: the TopStruct of N = the TopStruct of N;
  let g be Function of [:N,N qua TopSpace:], N;
  assume g = inf_op N;
  hence thesis by A2,A7,A8,YELLOW12:36;
end;

Lm3: now
  let S, T, x1, x2 be set such that
A1: x1 in S and
A2: x2 in T;
A3: dom <:pr2(S,T),pr1(S,T):> = dom pr2(S,T) /\ dom pr1(S,T) by FUNCT_3:def 7
    .= dom pr2(S,T) /\ [:S,T:] by FUNCT_3:def 4
    .= [:S,T:] /\ [:S,T:] by FUNCT_3:def 5
    .= [:S,T:];
  [x1,x2] in [:S,T:] by A1,A2,ZFMISC_1:87;
  hence
  <:pr2(S,T),pr1(S,T):>. [x1,x2] = [pr2(S,T).(x1,x2),pr1(S,T).(x1,x2)] by A3,
FUNCT_3:def 7
    .= [x2,pr1(S,T).(x1,x2)] by A1,A2,FUNCT_3:def 5
    .= [x2,x1] by A1,A2,FUNCT_3:def 4;
end;

:: Proposition 2.4, p. 153

theorem
  for N being meet-continuous Lawson complete TopLattice st InclPoset
sigma N is continuous holds N is Hausdorff iff for X being Subset of [:N,N qua
  TopSpace:] st X = the InternalRel of N holds X is closed
proof
  let N be meet-continuous Lawson complete TopLattice such that
A1: InclPoset sigma N is continuous;
A2: [:the carrier of N,the carrier of N:] = the carrier of [:N,N qua
  TopSpace:] by BORSUK_1:def 2;
  hereby
    reconsider D = id the carrier of N as Subset of [:N,N qua TopSpace:] by
BORSUK_1:def 2;
    set INF = inf_op N, f = <:pr1(the carrier of N,the carrier of N),INF:>;
    assume N is Hausdorff;
    then
A3: D is closed by YELLOW12:46;
A4: the carrier of [:N,N:] = [:the carrier of N,the carrier of N:] by
YELLOW_3:def 2;
    then reconsider
    f as Function of [:N,N qua TopSpace:], [:N,N qua TopSpace:] by A2,
FUNCT_3:58;
    let X be Subset of [:N,N qua TopSpace:] such that
A5: X = the InternalRel of N;
A6: for x, y being Element of N holds f. [x,y] = [x, x "/\" y]
    proof
      let x, y be Element of N;
A7:   dom (pr1(the carrier of N,the carrier of N)) = [:the carrier of N,
      the carrier of N:] by FUNCT_2:def 1;
A8:   [x,y] in [:the carrier of N,the carrier of N:] by ZFMISC_1:87;
      dom INF = [:the carrier of N,the carrier of N:] by A4,FUNCT_2:def 1;
      hence
      f. [x,y] = [pr1(the carrier of N,the carrier of N).(x,y),INF.(x,y)]
      by A8,A7,FUNCT_3:49
        .= [x, INF.(x,y)] by FUNCT_3:def 4
        .= [x, x "/\" y] by WAYBEL_2:def 4;
    end;
A9: X = f"D
    proof
      hereby
        let a be object;
        assume
A10:    a in X;
        then consider s, t being object such that
A11:    s in the carrier of N and
A12:    t in the carrier of N and
A13:    a = [s,t] by A5,ZFMISC_1:def 2;
        reconsider s, t as Element of N by A11,A12;
        s <= t by A5,A10,A13,ORDERS_2:def 5;
        then s "/\" t = s by YELLOW_0:25;
        then f. [s,t] = [s,s] by A6;
        then
A14:    f.a in D by A13,RELAT_1:def 10;
        dom f = the carrier of [:N,N qua TopSpace:] by FUNCT_2:def 1;
        then a in dom f by A2,A11,A12,A13,ZFMISC_1:87;
        hence a in f"D by A14,FUNCT_1:def 7;
      end;
      let a be object;
      assume
A15:  a in f"D;
      then
A16:  f.a in D by FUNCT_1:def 7;
      consider s, t being object such that
A17:  s in the carrier of N and
A18:  t in the carrier of N and
A19:  a = [s,t] by A2,A15,ZFMISC_1:def 2;
      reconsider s, t as Element of N by A17,A18;
      f.a = [s, s "/\" t] by A6,A19;
      then s = s "/\" t by A16,RELAT_1:def 10;
      then s <= t by YELLOW_0:25;
      hence thesis by A5,A19,ORDERS_2:def 5;
    end;
    reconsider INF as Function of [:N,N qua TopSpace:], N by A2,A4;
    N is topological_semilattice by A1,Th22;
    then
A20: INF is continuous;
    pr1(the carrier of N,the carrier of N) is continuous Function of [:N,
    N qua TopSpace:],N by YELLOW12:39;
    then f is continuous by A20,YELLOW12:41;
    hence X is closed by A9,A3;
  end;
  assume
A21: for X being Subset of [:N,N qua TopSpace:] st X = the InternalRel
  of N holds X is closed;
A22: (the InternalRel of N) /\ the InternalRel of N~ c= id the carrier of N
  by YELLOW12:23;
  id the carrier of N c= (the InternalRel of N) /\ the InternalRel of N~
  by YELLOW12:22;
  then
A23: id the carrier of N = (the InternalRel of N) /\ the InternalRel of N~
  by A22;
  for A being Subset of [:N,N qua TopSpace:] st A = id the carrier of N
  holds A is closed
  proof
    reconsider f = <:pr2(the carrier of N,the carrier of N), pr1(the carrier
of N,the carrier of N):> as continuous Function of [:N,N qua TopSpace:], [:N,N
    qua TopSpace:] by YELLOW12:42;
    reconsider X = the InternalRel of N, Y = the InternalRel of N~ as Subset
    of [:N,N qua TopSpace:] by BORSUK_1:def 2;
    let A be Subset of [:N,N qua TopSpace:] such that
A24: A = id the carrier of N;
    reconsider X, Y as Subset of [:N,N qua TopSpace:];
A25: X is closed by A21;
A26: dom f = [:the carrier of N,the carrier of N:] by YELLOW12:4;
A27: f.:X = Y
    proof
      thus f.:X c= Y
      proof
        let y be object;
        assume y in f.:X;
        then consider x being object such that
        x in dom f and
A28:    x in X and
A29:    y = f.x by FUNCT_1:def 6;
        consider x1, x2 being object such that
A30:    x1 in the carrier of N and
A31:    x2 in the carrier of N and
A32:    x = [x1,x2] by A28,ZFMISC_1:def 2;
        f.x = [x2,x1] by A30,A31,A32,Lm3;
        hence thesis by A28,A29,A32,RELAT_1:def 7;
      end;
      let y be object;
      assume
A33:  y in Y;
      then consider y1, y2 being object such that
A34:  y1 in the carrier of N and
A35:  y2 in the carrier of N and
A36:  y = [y1,y2] by ZFMISC_1:def 2;
A37:  [y2,y1] in X by A33,A36,RELAT_1:def 7;
      f. [y2,y1] = y by A34,A35,A36,Lm3;
      hence thesis by A26,A37,FUNCT_1:def 6;
    end;
    f is being_homeomorphism by YELLOW12:43;
    then Y is closed by A25,A27,TOPS_2:58;
    hence thesis by A23,A24,A25;
  end;
  hence thesis by YELLOW12:46;
end;

:: Definition 2.5, p. 154

definition
  let N be non empty reflexive RelStr, X be Subset of N;
  func X^0 -> Subset of N equals
  { u where u is Element of N : for D being non
  empty directed Subset of N st u <= sup D holds X meets D };
  coherence
  proof
    defpred P[Element of N] means for D being non empty directed Subset of N
    st $1 <= sup D holds X meets D;
    thus {u where u is Element of N: P[u]} is Subset of N from DOMAIN_1:sch 7;
  end;
end;

registration
  let N be non empty reflexive antisymmetric RelStr, X be empty Subset of N;
  cluster X^0 -> empty;
  coherence
  proof
    X^0 c= {}
    proof
      let a be object such that
A1:   a in X^0 and
      not a in {};
      consider u being Element of N such that
      a = u and
A2:   for D being non empty directed Subset of N st u <= sup D holds X
      meets D by A1;
      reconsider D = {u} as non empty directed Subset of N by WAYBEL_0:5;
A3:   X misses D;
      u <= sup D by YELLOW_0:39;
      hence contradiction by A3,A2;
    end;
    hence thesis;
  end;
end;

theorem
  for N being non empty reflexive RelStr, A, J being Subset of N st A c=
  J holds A^0 c= J^0
proof
  let N be non empty reflexive RelStr, A, J be Subset of N such that
A1: A c= J;
  let a be object;
  assume a in A^0;
  then consider u being Element of N such that
A2: a = u and
A3: for D being non empty directed Subset of N st u <= sup D holds A meets D;
  for D being non empty directed Subset of N st u <= sup D holds J meets D
  by A1,A3,XBOOLE_1:63;
  hence thesis by A2;
end;

:: Remark 2.6 (i), p. 154

theorem Th25:
  for N being non empty reflexive RelStr, x being Element of N
  holds (uparrow x)^0 = wayabove x
proof
  let N be non empty reflexive RelStr, x be Element of N;
  thus (uparrow x)^0 c= wayabove x
  proof
    let a be object;
    assume a in (uparrow x)^0;
    then consider u being Element of N such that
A1: a = u and
A2: for D being non empty directed Subset of N st u <= sup D holds (
    uparrow x) meets D;
    u >> x
    proof
      let D be non empty directed Subset of N;
      assume u <= sup D;
      then (uparrow x) meets D by A2;
      then consider d being object such that
A3:   d in (uparrow x) /\ D by XBOOLE_0:4;
      reconsider d as Element of N by A3;
      take d;
      thus d in D by A3,XBOOLE_0:def 4;
      d in uparrow x by A3,XBOOLE_0:def 4;
      hence thesis by WAYBEL_0:18;
    end;
    hence thesis by A1;
  end;
  let a be object;
  assume
A4: a in wayabove x;
  then reconsider b = a as Element of N;
  now
A5: b >> x by A4,WAYBEL_3:8;
    let D be non empty directed Subset of N;
    assume b <= sup D;
    then consider d being Element of N such that
A6: d in D and
A7: x <= d by A5;
    d in uparrow x by A7,WAYBEL_0:18;
    hence (uparrow x) meets D by A6,XBOOLE_0:3;
  end;
  hence thesis;
end;

:: Remark 2.6 (ii), p. 154

theorem Th26:
  for N being Scott TopLattice, X being upper Subset of N holds Int X c= X^0
proof
  let N be Scott TopLattice, X be upper Subset of N;
  let x be object;
  assume
A1: x in Int X;
  then reconsider y = x as Element of N;
  now
A2: Int X is upper inaccessible by WAYBEL11:def 4;
    let D be non empty directed Subset of N;
    assume y <= sup D;
    then sup D in Int X by A2,A1;
    then D meets Int X by A2;
    hence X meets D by TOPS_1:16,XBOOLE_1:63;
  end;
  hence thesis;
end;

:: Lemma 2.7 (i), p. 154

theorem Th27:
  for N being non empty reflexive RelStr, X, Y being Subset of N
  holds (X^0) \/ (Y^0) c= (X \/ Y)^0
proof
  let N be non empty reflexive RelStr, X, Y be Subset of N;
  let a be object;
  assume
A1: a in (X^0) \/ (Y^0);
  then reconsider b = a as Element of N;
  now
    let D be non empty directed Subset of N such that
A2: b <= sup D;
    now
      per cases by A1,XBOOLE_0:def 3;
      suppose
        a in X^0;
        then ex x being Element of N st a = x & for D being
        non empty directed Subset of N st x <= sup D holds X meets D;
        then X meets D by A2;
        then X /\ D <> {};
        then X /\ D \/ Y /\ D <> {};
        hence (X \/ Y) /\ D <> {} by XBOOLE_1:23;
      end;
      suppose
        a in Y^0;
        then ex y being Element of N st a = y & for D being
        non empty directed Subset of N st y <= sup D holds Y meets D;
        then Y meets D by A2;
        then Y /\ D <> {};
        then X /\ D \/ Y /\ D <> {};
        hence (X \/ Y) /\ D <> {} by XBOOLE_1:23;
      end;
    end;
    hence (X \/ Y) meets D;
  end;
  hence thesis;
end;

:: Lemma 2.7 (ii), p. 154

theorem Th28:
  for N being meet-continuous LATTICE, X, Y being upper Subset of
  N holds (X^0) \/ (Y^0) = (X \/ Y)^0
proof
  let N be meet-continuous LATTICE, X, Y be upper Subset of N;
  thus (X^0) \/ (Y^0) c= (X \/ Y)^0 by Th27;
  assume not (X \/ Y)^0 c= (X^0) \/ (Y^0);
  then consider s being object such that
A1: s in (X \/ Y)^0 and
A2: not s in (X^0) \/ (Y^0);
A3: not s in X^0 by A2,XBOOLE_0:def 3;
A4: not s in Y^0 by A2,XBOOLE_0:def 3;
  reconsider s as Element of N by A1;
  consider D being non empty directed Subset of N such that
A5: s <= sup D and
A6: X misses D by A3;
  consider E being non empty directed Subset of N such that
A7: s <= sup E and
A8: Y misses E by A4;
  s "/\" s = s by YELLOW_0:25;
  then s <= (sup D) "/\" (sup E) by A5,A7,YELLOW_3:2;
  then
A9: s <= sup (D "/\" E) by WAYBEL_2:51;
  ex xy being Element of N st s = xy & for D being non
  empty directed Subset of N st xy <= sup D holds (X \/ Y) meets D by A1;
  then (X \/ Y) meets (D"/\"E) by A9;
  then
A10: (X \/ Y) /\ (D"/\"E) <> {};
  X misses (D "/\" E) by A6,YELLOW12:21;
  then
A11: X /\ (D "/\" E) = {};
  Y misses (D "/\" E) by A8,YELLOW12:21;
  then X /\ (D"/\"E) \/ Y /\ (D"/\"E) = {} by A11;
  hence contradiction by A10,XBOOLE_1:23;
end;

:: Lemma 2.8, p. 154

theorem Th29:
  for S being meet-continuous Scott TopLattice, F being finite
Subset of S holds Int uparrow F c= union { wayabove x where x is Element of S :
  x in F }
proof
  let S be meet-continuous Scott TopLattice, F be finite Subset of S;
  defpred P[set] means ex UU being Subset-Family of S st UU = {uparrow x where
x is Element of S : x in $1} & (union UU)^0 = union { (uparrow x)^0 where x is
  Element of S : x in $1 };
A1: for b, J being set st b in F & J c= F & P[J] holds P[J \/ {b}]
  proof
    let b, J be set;
    assume that
A2: b in F and
    J c= F;
    reconsider bb = b as Element of S by A2;
A3: (union {(uparrow x)^0 where x is Element of S : x in J}) \/ ((uparrow
    bb)^0) = union {(uparrow x)^0 where x is Element of S : x in J \/ {b}}
    proof
      {(uparrow x)^0 where x is Element of S : x in J} c= {(uparrow x)^0
      where x is Element of S : x in J \/ {b}}
      proof
        let a be object;
        assume a in {(uparrow x)^0 where x is Element of S : x in J};
        then
A4:     ex y being Element of S st a = (uparrow y)^0 & y in J;
        J c= J \/ {b} by XBOOLE_1:7;
        hence thesis by A4;
      end;
      then
A5:   union {(uparrow x)^0 where x is Element of S : x in J} c= union {(
      uparrow x)^0 where x is Element of S : x in J \/ {b}} by ZFMISC_1:77;
A6:   {b} c= J \/ {b} by XBOOLE_1:7;
      b in {b} by TARSKI:def 1;
      then (uparrow bb)^0 in {(uparrow x)^0 where x is Element of S : x in J
      \/ {b}} by A6;
      then (uparrow bb)^0 c= union {(uparrow x)^0 where x is Element of S : x
      in J \/ {b}} by ZFMISC_1:74;
      hence (union {(uparrow x)^0 where x is Element of S : x in J}) \/ ((
uparrow bb)^0) c= union {(uparrow x)^0 where x is Element of S : x in J \/ {b}}
      by A5,XBOOLE_1:8;
      let a be object;
      assume
      a in union {(uparrow x)^0 where x is Element of S : x in J \/ { b}};
      then consider A being set such that
A7:   a in A and
A8:   A in {(uparrow x)^0 where x is Element of S : x in J \/ {b}} by
TARSKI:def 4;
      consider y being Element of S such that
A9:   A = (uparrow y)^0 and
A10:  y in J \/ {b} by A8;
      per cases by A10,XBOOLE_0:def 3;
      suppose
        y in J;
        then
        (uparrow y)^0 in {(uparrow x)^0 where x is Element of S : x in J};
        then
A11:    a in union {(uparrow x)^0 where x is Element of S : x in J } by A7,A9,
TARSKI:def 4;
        union {(uparrow x)^0 where x is Element of S : x in J} c= (union
{(uparrow x)^0 where x is Element of S : x in J}) \/ ((uparrow bb)^0) by
XBOOLE_1:7;
        hence thesis by A11;
      end;
      suppose
A12:    y in {b};
A13:    (uparrow bb)^0 c= (union {(uparrow x)^0 where x is Element of S :
        x in J}) \/ ((uparrow bb)^0) by XBOOLE_1:7;
        y = b by A12,TARSKI:def 1;
        hence thesis by A13,A7,A9;
      end;
    end;
    assume P[J];
    then consider UU being Subset-Family of S such that
A14: UU = {uparrow x where x is Element of S : x in J} and
A15: (union UU)^0 = union {(uparrow x)^0 where x is Element of S : x in J};
    reconsider I = UU \/ {uparrow bb} as Subset-Family of S;
    take I;
    thus I = {uparrow x where x is Element of S : x in J \/ {b}}
    proof
      thus I c= {uparrow x where x is Element of S : x in J \/ {b}}
      proof
        let a be object such that
A16:    a in I;
        per cases by A16,XBOOLE_0:def 3;
        suppose
A17:      a in UU;
A18:      J c= J \/ {b} by XBOOLE_1:7;
          ex x being Element of S st a = uparrow x & x in J by A17,A14;
          hence thesis by A18;
        end;
        suppose
A19:      a in {uparrow bb};
A20:      b in {b} by TARSKI:def 1;
A21:      {b} c= J \/ {b} by XBOOLE_1:7;
          a = uparrow bb by A19,TARSKI:def 1;
          hence thesis by A20,A21;
        end;
      end;
      let a be object;
      assume a in {uparrow x where x is Element of S : x in J \/ {b}};
      then consider x being Element of S such that
A22:  a = uparrow x and
A23:  x in J \/ {b};
      per cases by A23,XBOOLE_0:def 3;
      suppose
A24:    x in J;
A25:    UU c= UU \/ {uparrow bb} by XBOOLE_1:7;
        uparrow x in UU by A24,A14;
        hence thesis by A25,A22;
      end;
      suppose
A26:    x in {b};
A27:    {uparrow bb} c= UU \/ {uparrow bb} by XBOOLE_1:7;
A28:    a in {uparrow x} by A22,TARSKI:def 1;
        x = b by A26,TARSKI:def 1;
        hence thesis by A27,A28;
      end;
    end;
A29: (union UU) \/ uparrow bb = union I
    proof
      thus (union UU) \/ uparrow bb c= union I
      proof
        let a be object such that
A30:    a in (union UU) \/ uparrow bb;
        per cases by A30,XBOOLE_0:def 3;
        suppose
A31:      a in union UU;
A32:      UU c= I by XBOOLE_1:7;
          ex A being set st a in A & A in UU by A31,TARSKI:def 4;
          hence thesis by A32,TARSKI:def 4;
        end;
        suppose
A33:      a in uparrow bb;
A34:      uparrow bb in {uparrow bb} by TARSKI:def 1;
          {uparrow bb} c= UU \/ {uparrow bb} by XBOOLE_1:7;
          hence thesis by A34,A33,TARSKI:def 4;
        end;
      end;
      let a be object;
      assume a in union I;
      then consider A being set such that
A35:  a in A and
A36:  A in I by TARSKI:def 4;
      per cases by A36,XBOOLE_0:def 3;
      suppose
        A in UU;
        then A c= union UU by ZFMISC_1:74;
        then
A37:    a in union UU by A35;
        union UU c= (union UU) \/ uparrow bb by XBOOLE_1:7;
        hence thesis by A37;
      end;
      suppose
A38:    A in {uparrow bb};
A39:    uparrow bb c= (union UU) \/ uparrow bb by XBOOLE_1:7;
        A = uparrow bb by A38,TARSKI:def 1;
        hence thesis by A39,A35;
      end;
    end;
    for X being Subset of S st X in UU holds X is upper
    proof
      let X be Subset of S;
      assume X in UU;
      then ex x being Element of S st X = uparrow x & x in J by A14;
      hence thesis;
    end;
    then union UU is upper by WAYBEL_0:28;
    hence thesis by A3,A15,A29,Th28;
  end;
A40: P[{}]
  proof
    deffunc F(Element of S) = (uparrow $1)^0;
    reconsider UU = {} as Subset-Family of S by XBOOLE_1:2;
    take UU;
    reconsider K = union UU as empty Subset of S;
A41: K^0 is empty;
    thus UU = {uparrow x where x is Element of S : x in {}}
    proof
      deffunc F(Element of S) = uparrow $1;
      {F(x) where x is Element of S : x in {}} = {} from EmptySch;
      hence thesis;
    end;
    {F(x) where x is Element of S : x in {}} = {} from EmptySch;
    hence thesis by A41;
  end;
A42: {(uparrow x)^0 where x is Element of S : x in F} = {wayabove x where x
  is Element of S : x in F}
  proof
    thus {(uparrow x)^0 where x is Element of S : x in F} c= {wayabove x where
    x is Element of S : x in F}
    proof
      let a be object;
      assume a in {(uparrow x)^0 where x is Element of S : x in F};
      then consider x being Element of S such that
A43:  a = (uparrow x)^0 and
A44:  x in F;
      (uparrow x)^0 = wayabove x by Th25;
      hence thesis by A43,A44;
    end;
    let a be object;
    assume a in {wayabove x where x is Element of S : x in F};
    then consider x being Element of S such that
A45: a = wayabove x and
A46: x in F;
    (uparrow x)^0 = wayabove x by Th25;
    hence thesis by A45,A46;
  end;
A47: F is finite;
  P[F] from FINSET_1:sch 2(A47,A40,A1);
  then (uparrow F)^0 = union {wayabove x where x is Element of S : x in F} by
A42,YELLOW_9:4;
  hence thesis by Th26;
end;

:: Theorem 2.9, p. 154

theorem Th30:
  for N being Lawson complete TopLattice holds N is continuous
  iff N is meet-continuous Hausdorff
proof
  let N be Lawson complete TopLattice;
  thus N is continuous implies N is meet-continuous Hausdorff;
  assume
A1: N is meet-continuous Hausdorff;
  thus
A2: for x being Element of N holds waybelow x is non empty directed;
  thus N is up-complete;
  for x, y being Element of N st not x <= y ex u being Element of N st u
  << x & not u <= y
  proof
    reconsider J = {O\uparrow F where O, F is Subset of N: O in sigma N & F is
    finite} as Basis of N by WAYBEL19:32;
    set S = the Scott TopAugmentation of N;
A3: for N being Semilattice, x, y being Element of N st ex u being
Element of N st u << x & not u <= x "/\" y ex u being Element of N st u << x &
    not u <= y
    proof
      let N be Semilattice, x, y be Element of N;
      given u being Element of N such that
A4:   u << x and
A5:   not u <= x "/\" y;
      take u;
      thus u << x by A4;
      assume
A6:   u <= y;
      u <= x by A4,WAYBEL_3:1;
      then u "/\" u <= x "/\" y by A6,YELLOW_3:2;
      hence contradiction by A5,YELLOW_0:25;
    end;
    let x, y be Element of N;
    assume not x <= y;
    then x "/\" y <> x by YELLOW_0:23;
    then consider W, V being Subset of N such that
A7: W is open and
A8: V is open and
A9: x in W and
A10: x "/\" y in V and
A11: W misses V by A1;
    V = union {G where G is Subset of N: G in J & G c= V} by A8,YELLOW_8:9;
    then consider K being set such that
A12: x "/\" y in K and
A13: K in {G where G is Subset of N: G in J & G c= V} by A10,TARSKI:def 4;
    consider V1 being Subset of N such that
A14: K = V1 and
A15: V1 in J and
A16: V1 c= V by A13;
    consider U2, F being Subset of N such that
A17: V1 = U2\uparrow F and
A18: U2 in sigma N and
A19: F is finite by A15;
A20: the RelStr of S = the RelStr of N by YELLOW_9:def 4;
    then reconsider x1 = x, y1 = y as Element of S;
A21: ex_inf_of {x1,y1},S by YELLOW_0:21;
    reconsider U1 = U2 as Subset of S by A20;
    reconsider WU1 = W /\ U2 as Subset of N;
    reconsider W1 = WU1 as Subset of S by A20;
A22: uparrow W1 = uparrow WU1 by A20,WAYBEL_0:13;
    U2 in sigma S by A20,A18,YELLOW_9:52;
    then
A23: U1 is open by WAYBEL14:24;
    then
A24: U1 is upper by WAYBEL11:def 4;
    WU1 c= uparrow F
    proof
A25:  W misses V1 by A11,A16,XBOOLE_1:63;
A26:  WU1 \ uparrow F c= U1 \ uparrow F by XBOOLE_1:17,33;
      let w be object;
      assume that
A27:  w in WU1 and
A28:  not w in uparrow F;
A29:  w in W by A27,XBOOLE_0:def 4;
      w in WU1 \ uparrow F by A27,A28,XBOOLE_0:def 5;
      hence contradiction by A26,A17,A29,A25,XBOOLE_0:3;
    end;
    then WU1 is_coarser_than uparrow F by WAYBEL12:16;
    then
A30: uparrow WU1 c= uparrow F by YELLOW12:28;
A31: x1 "/\" y1 <= x1 by YELLOW_0:23;
    x "/\" y = inf {x,y} by YELLOW_0:40
      .= "/\"({x1,y1},S) by A20,A21,YELLOW_0:27
      .= x1 "/\" y1 by YELLOW_0:40;
    then x1 "/\" y1 in U1 by A12,A14,A17,XBOOLE_0:def 5;
    then x1 in U1 by A24,A31;
    then
A32: x in W1 by A9,XBOOLE_0:def 4;
    W1 c= uparrow W1 by WAYBEL_0:16;
    then
A33: x in uparrow W1 by A32;
    reconsider F1 = F as finite Subset of S by A20,A19;
A34: uparrow F1 = uparrow F by A20,WAYBEL_0:13;
    N is Lawson correct TopAugmentation of S by A20,YELLOW_9:def 4;
    then U2 is open by A23,WAYBEL19:37;
    then uparrow W1 c= Int uparrow F1 by A7,A1,A30,A22,A34,Th15,TOPS_1:24;
    then
A35: x in Int uparrow F1 by A33;
    S is meet-continuous by A1,A20,YELLOW12:14;
    then Int uparrow F1 c= union { wayabove u where u is Element of S : u in
    F1 } by Th29;
    then consider A being set such that
A36: x in A and
A37: A in { wayabove u where u is Element of S : u in F1 } by A35,TARSKI:def 4;
    consider u being Element of S such that
A38: A = wayabove u and
A39: u in F1 by A37;
    reconsider u1 = u as Element of N by A20;
A40: wayabove u1 = wayabove u by A20,YELLOW12:13;
    now
      take u1;
      thus u1 << x by A36,A38,A40,WAYBEL_3:8;
      uparrow u1 c= uparrow F by A39,YELLOW12:30;
      then not x "/\" y in uparrow u1 by A12,A14,A17,XBOOLE_0:def 5;
      hence not u1 <= x "/\" y by WAYBEL_0:18;
    end;
    then consider u2 being Element of N such that
A41: u2 << x and
A42: not u2 <= y by A3;
    take u2;
    thus thesis by A41,A42;
  end;
  hence thesis by A2,WAYBEL_3:24;
end;

registration
  cluster continuous Lawson -> Hausdorff for complete TopLattice;
  coherence;
  cluster meet-continuous Lawson Hausdorff -> continuous for
complete TopLattice;
  coherence by Th30;
end;

:: Definition 2.10, p. 155

definition
  let N be non empty TopRelStr;
  attr N is with_small_semilattices means
  for x being Point of N ex J being
  basis of x st for A being Subset of N st A in J holds subrelstr A is
  meet-inheriting;
  attr N is with_compact_semilattices means
  for x being Point of N ex J being
  basis of x st for A being Subset of N st A in J holds subrelstr A is
  meet-inheriting & A is compact;
  attr N is with_open_semilattices means
  :Def4:
  for x being Point of N ex J
  being Basis of x st for A being Subset of N st A in J holds subrelstr A is
  meet-inheriting;
end;

registration
  cluster with_open_semilattices -> with_small_semilattices for non empty
    TopSpace-like TopRelStr;
  coherence
  proof
    let N be non empty TopSpace-like TopRelStr;
    assume
A1: for x being Point of N ex J being Basis of x st for A being Subset
    of N st A in J holds subrelstr A is meet-inheriting;
    let x be Point of N;
    consider J being Basis of x such that
A2: for A being Subset of N st A in J holds subrelstr A is
    meet-inheriting by A1;
    reconsider J as basis of x by YELLOW13:23;
    take J;
    thus thesis by A2;
  end;
  cluster with_compact_semilattices -> with_small_semilattices for non empty
    TopSpace-like TopRelStr;
  coherence
  proof
    let N be non empty TopSpace-like TopRelStr;
    assume
A3: for x being Point of N ex J being basis of x st for A being Subset
    of N st A in J holds subrelstr A is meet-inheriting & A is compact;
    let x be Point of N;
    consider J being basis of x such that
A4: for A being Subset of N st A in J holds subrelstr A is
    meet-inheriting & A is compact by A3;
    take J;
    thus thesis by A4;
  end;
  cluster anti-discrete -> with_small_semilattices with_open_semilattices for
non
    empty TopRelStr;
  coherence
  proof
    let T be non empty TopRelStr;
    assume T is anti-discrete;
    then reconsider W = T as anti-discrete non empty TopRelStr;
    set J = {the carrier of W};
A5: now
      let A be Subset of W;
A6:   subrelstr [#]W is infs-inheriting;
      assume A in J;
      then reconsider
      K = subrelstr A as infs-inheriting SubRelStr of T by A6,TARSKI:def 1;
      K is meet-inheriting;
      hence subrelstr A is meet-inheriting;
    end;
A7: W is with_open_semilattices
    proof
      let x be Point of W;
      reconsider J as Basis of x by YELLOW13:13;
      take J;
      let A be Subset of W;
      assume A in J;
      hence thesis by A5;
    end;
    W is with_small_semilattices
    proof
      let x be Point of W;
      reconsider J as basis of x by YELLOW13:21;
      take J;
      let A be Subset of W;
      assume A in J;
      hence thesis by A5;
    end;
    hence thesis by A7;
  end;
  cluster reflexive TopSpace-like -> with_compact_semilattices
       for 1-element TopRelStr;
  coherence
  proof
    let T be 1-element TopRelStr;
    assume T is reflexive TopSpace-like;
    then reconsider W = T as reflexive 1-element TopSpace-like TopRelStr;
    W is with_compact_semilattices
    proof
      let x be Point of W;
      reconsider J = {the carrier of W} as basis of x by YELLOW13:21;
      take J;
      let A be Subset of W;
      assume
A8:   A in J;
      subrelstr [#]W is infs-inheriting;
      then reconsider K = subrelstr A as infs-inheriting SubRelStr of T by A8,
TARSKI:def 1;
      K is meet-inheriting;
      hence subrelstr A is meet-inheriting;
      A = [#]W by A8,TARSKI:def 1;
      hence thesis;
    end;
    hence thesis;
  end;
end;

registration
  cluster strict trivial lower for TopLattice;
  existence
  proof
    set T = the strict 1-element TopLattice;
    take T;
    thus thesis;
  end;
end;

theorem Th31:
  for N being topological_semilattice with_infima TopPoset, C
  being Subset of N st subrelstr C is meet-inheriting holds subrelstr Cl C is
  meet-inheriting
proof
  let N be topological_semilattice with_infima TopPoset, C be Subset of N
  such that
A1: subrelstr C is meet-inheriting;
  set A = Cl C, S = subrelstr A;
  let x, y be Element of N such that
A2: x in the carrier of S and
A3: y in the carrier of S and
  ex_inf_of {x,y},N;
A4: the carrier of S = A by YELLOW_0:def 15;
  for V being a_neighborhood of x "/\" y holds V meets C
  proof
    set NN = [:N,N qua TopSpace:];
    let V be a_neighborhood of x "/\" y;
A5: the carrier of NN = [:the carrier of N,the carrier of N:] by BORSUK_1:def 2
;
    then reconsider xy = [x,y] as Point of NN by YELLOW_3:def 2;
    the carrier of [:N,N:] = [:the carrier of N,the carrier of N:] by
YELLOW_3:def 2;
    then reconsider f = inf_op N as Function of NN, N by A5;
A6: f.xy = f.(x,y) .= x "/\" y by WAYBEL_2:def 4;
    f is continuous by YELLOW13:def 5;
    then consider H being a_neighborhood of xy such that
A7: f.:H c= V by A6,BORSUK_1:def 1;
    consider A being Subset-Family of NN such that
A8: Int H = union A and
A9: for e being set st e in A ex X1, Y1 being Subset of N st e = [:X1
    ,Y1:] & X1 is open & Y1 is open by BORSUK_1:5;
    xy in union A by A8,CONNSP_2:def 1;
    then consider K being set such that
A10: xy in K and
A11: K in A by TARSKI:def 4;
    consider Ix, Iy being Subset of N such that
A12: K = [:Ix,Iy:] and
A13: Ix is open and
A14: Iy is open by A9,A11;
A15: x in Ix by A10,A12,ZFMISC_1:87;
A16: y in Iy by A10,A12,ZFMISC_1:87;
A17: Ix = Int Ix by A13,TOPS_1:23;
    Iy = Int Iy by A14,TOPS_1:23;
    then reconsider Iy as a_neighborhood of y by A16,CONNSP_2:def 1;
    Iy meets C by A3,A4,CONNSP_2:27;
    then consider iy being object such that
A18: iy in Iy and
A19: iy in C by XBOOLE_0:3;
    reconsider Ix as a_neighborhood of x by A15,A17,CONNSP_2:def 1;
    Ix meets C by A2,A4,CONNSP_2:27;
    then consider ix being object such that
A20: ix in Ix and
A21: ix in C by XBOOLE_0:3;
    reconsider ix, iy as Element of N by A20,A18;
    now
      [ix,iy] in K by A12,A20,A18,ZFMISC_1:87;
      then
A22:  [ix,iy] in Int H by A8,A11,TARSKI:def 4;
      take a = ix "/\" iy;
A23:  dom f = the carrier of [:N,N:] by FUNCT_2:def 1;
A24:  Int H c= H by TOPS_1:16;
      f.(ix,iy) = ix "/\" iy by WAYBEL_2:def 4;
      then ix "/\" iy in f.:H by A24,A23,A22,FUNCT_1:def 6;
      hence a in V by A7;
A25:  ex_inf_of {ix,iy},N by YELLOW_0:21;
      the carrier of subrelstr C = C by YELLOW_0:def 15;
      then inf{ix,iy} in C by A25,A1,A21,A19;
      hence a in C by YELLOW_0:40;
    end;
    hence thesis by XBOOLE_0:3;
  end;
  then x "/\" y in Cl C by CONNSP_2:27;
  hence thesis by A4,YELLOW_0:40;
end;

:: Theorem 2.11, p. 155

theorem Th32:
  for N being meet-continuous Lawson complete TopLattice for S
being Scott TopAugmentation of N holds (for x being Point of S ex J being Basis
  of x st for W being Subset of S st W in J holds W is Filter of S) iff N is
  with_open_semilattices
proof
  let N be meet-continuous Lawson complete TopLattice, S be Scott
  TopAugmentation of N;
A1: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  hereby
    assume
A2: for x being Point of S ex J being Basis of x st for W being Subset
    of S st W in J holds W is Filter of S;
    thus N is with_open_semilattices
    proof
      let x be Point of N;
      defpred P[set] means ex U1 being Filter of N, F being finite Subset of N
, W1 being Subset of N st $1 = W1 & U1 \ uparrow F = $1 & x in $1 & W1 is open;
      consider SF being Subset-Family of N such that
A3:   for W being Subset of N holds W in SF iff P[W] from SUBSET_1:
      sch 3;
      reconsider SF as Subset-Family of N;
A4:   now
        reconsider BL = {O\uparrow F where O, F is Subset of N: O in sigma N &
        F is finite} as Basis of N by WAYBEL19:32;
A5:     BL c= the topology of N by TOPS_2:64;
        reconsider y = x as Point of S by A1;
        let W be Subset of N such that
A6:     W is open and
A7:     x in W;
        consider By being Basis of y such that
A8:     for A being Subset of S st A in By holds A is Filter of S by A2;
        W = union { G where G is Subset of N: G in BL & G c= W } by A6,
YELLOW_8:9;
        then consider K being set such that
A9:     x in K and
A10:    K in { G where G is Subset of N: G in BL & G c= W } by A7,TARSKI:def 4;
        consider G being Subset of N such that
A11:    K = G and
A12:    G in BL and
A13:    G c= W by A10;
        consider V, F being Subset of N such that
A14:    G = V \ uparrow F and
A15:    V in sigma N and
A16:    F is finite by A12;
        reconsider F as finite Subset of N by A16;
A17:    not x in uparrow F by A9,A11,A14,XBOOLE_0:def 5;
        reconsider V as Subset of S by A1;
A18:    y in V by A9,A11,A14,XBOOLE_0:def 5;
A19:    sigma N = sigma S by A1,YELLOW_9:52;
        then V is open by A15,WAYBEL14:24;
        then consider U1 being Subset of S such that
A20:    U1 in By and
A21:    U1 c= V by A18,YELLOW_8:13;
        reconsider U2 = U1 as Subset of N by A1;
        U1 is Filter of S by A8,A20;
        then reconsider U2 as Filter of N by A1,WAYBEL_0:4,25;
        U2 \ uparrow F is Subset of N;
        then reconsider IT = U1 \ uparrow F as Subset of N;
        take U2, F, IT;
        thus IT = U2 \ uparrow F;
        y in U1 by A20,YELLOW_8:12;
        hence x in IT by A17,XBOOLE_0:def 5;
        U1 is open by A20,YELLOW_8:12;
        then U1 in sigma S by WAYBEL14:24;
        then IT in BL by A19;
        hence IT is open by A5;
        IT c= G by A14,A21,XBOOLE_1:33;
        hence IT c= W by A13;
      end;
      SF is Basis of x
      proof
A22:    SF is open
        proof
          let a be Subset of N;
          assume
A23:      a in SF;
          reconsider W = a as Subset of N;
          ex U1 being Filter of N, F being finite Subset of
N, W1 being Subset of N st W1 = W & U1 \ uparrow F = W & x in W & W1 is
          open by A3,A23;
          hence thesis;
        end;
        SF is x-quasi_basis
        proof
        for a being set st a in SF holds x in a
        proof
          let a be set;
          assume
A24:      a in SF;
          then reconsider W = a as Subset of N;
          ex U1 being Filter of N, F being finite Subset of
N, W1 being Subset of N st W1 = W & U1 \ uparrow F = W & x in W & W1 is
          open by A3,A24;
          hence thesis;
        end;
        hence x in Intersect SF by SETFAM_1:43;
        let W be Subset of N;
        assume that
A25:    W is open and
A26:    x in W;
        consider U2 being Filter of N, F being finite Subset of N, IT being
        Subset of N such that
A27:    IT = U2 \ uparrow F and
A28:    x in IT and
A29:    IT is open and
A30:    IT c= W by A25,A26,A4;
        take IT;
        thus thesis by A3,A27,A28,A29,A30;
      end;
      hence thesis by A22;
      end;
      then reconsider SF as Basis of x;
      take SF;
      let W be Subset of N;
      assume W in SF;
      then consider U1 being Filter of N, F being finite Subset of N, W1 being
      Subset of N such that
      W1 = W and
A31:  U1 \ uparrow F = W and
      x in W and
      W1 is open by A3;
      set SW = subrelstr W;
      thus SW is meet-inheriting
      proof
        let a, b be Element of N such that
A32:    a in the carrier of SW and
A33:    b in the carrier of SW and
        ex_inf_of {a,b},N;
A34:    the carrier of SW = W by YELLOW_0:def 15;
        then
A35:    b in U1 by A31,A33,XBOOLE_0:def 5;
A36:    not a in uparrow F by A34,A31,A32,XBOOLE_0:def 5;
        for y being Element of N st y <= a "/\" b holds not y in F
        proof
A37:      a "/\" b <= a by YELLOW_0:23;
          let y be Element of N;
          assume y <= a "/\" b;
          then y <= a by A37,ORDERS_2:3;
          hence thesis by A36,WAYBEL_0:def 16;
        end;
        then
A38:    not a "/\" b in uparrow F by WAYBEL_0:def 16;
        a in U1 by A34,A31,A32,XBOOLE_0:def 5;
        then consider z being Element of N such that
A39:    z in U1 and
A40:    z <= a and
A41:    z <= b by A35,WAYBEL_0:def 2;
        z "/\" z <= a "/\" b by A40,A41,YELLOW_3:2;
        then z <= a "/\" b by YELLOW_0:25;
        then a "/\" b in U1 by A39,WAYBEL_0:def 20;
        then a "/\" b in W by A38,A31,XBOOLE_0:def 5;
        hence thesis by A34,YELLOW_0:40;
      end;
    end;
  end;
  assume
A42: N is with_open_semilattices;
  let x be Point of S;
  reconsider y = x as Point of N by A1;
  consider J being Basis of y such that
A43: for A being Subset of N st A in J holds subrelstr A is
  meet-inheriting by A42;
  reconsider J9 = {uparrow A where A is Subset of N: A in J} as Basis of x by
Th16;
  take J9;
  let W be Subset of S;
  assume W in J9;
  then consider V being Subset of N such that
A44: W = uparrow V and
A45: V in J;
  subrelstr V is meet-inheriting by A43,A45;
  then
A46: V is filtered by YELLOW12:26;
  x in V by A45,YELLOW_8:12;
  hence thesis by A46,A1,A44,WAYBEL_0:4,25;
end;

:: Theorem 2.12, p. 155,  r => l

theorem Th33:
  for N being Lawson complete TopLattice for S being Scott
TopAugmentation of N for x being Element of N holds {inf A where A is Subset of
S: x in A & A in sigma S} c= {inf J where J is Subset of N : x in J & J in
  lambda N}
proof
  let N be Lawson complete TopLattice, S be Scott TopAugmentation of N, x be
  Element of N;
  set s = {inf A where A is Subset of S : x in A & A in sigma S};
  let k be object;
  assume k in s;
  then consider J being Subset of S such that
A1: k = inf J and
A2: x in J and
A3: J in sigma S;
A4: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  then reconsider A = J as Subset of N;
  sigma N c= lambda N by Th10;
  then
A5: sigma S c= lambda N by A4,YELLOW_9:52;
  inf A = inf J by A4,YELLOW_0:17,27;
  hence thesis by A5,A1,A2,A3;
end;

:: Theorem 2.12, p. 155

theorem Th34:
  for N being meet-continuous Lawson complete TopLattice for S
being Scott TopAugmentation of N for x being Element of N holds {inf A where A
is Subset of S : x in A & A in sigma S} = {inf J where J is Subset of N : x in
  J & J in lambda N}
proof
  let N be meet-continuous Lawson complete TopLattice, S be Scott
  TopAugmentation of N, x be Element of N;
  set l = {inf A where A is Subset of N : x in A & A in lambda N}, s = {inf J
  where J is Subset of S : x in J & J in sigma S};
  thus s c= l by Th33;
  let k be object;
  assume k in l;
  then consider A being Subset of N such that
A1: k = inf A and
A2: x in A and
A3: A in lambda N;
A4: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  then reconsider J = A as Subset of S;
  A is open by A3,Th12;
  then uparrow J is open by Th15;
  then
A5: uparrow J in sigma S by WAYBEL14:24;
A6: J c= uparrow J by WAYBEL_0:16;
  inf A = inf J by A4,YELLOW_0:17,27
    .= inf uparrow J by WAYBEL_0:38,YELLOW_0:17;
  hence thesis by A5,A1,A2,A6;
end;

:: Theorem 2.13, p. 155,  1 <=> 2

theorem Th35:
  for N being meet-continuous Lawson complete TopLattice holds N
is continuous iff N is with_open_semilattices & InclPoset sigma N is continuous
proof
  let N be meet-continuous Lawson complete TopLattice;
  set S = the Scott TopAugmentation of N;
A1: the RelStr of N = the RelStr of S by YELLOW_9:def 4;
  hereby
    assume
A2: N is continuous;
    for x being Point of S ex J being Basis of x st for W being Subset of
    S st W in J holds W is Filter of S
    proof
      let x be Point of S;
      consider J being Basis of x such that
A3:   for W being Subset of S st W in J holds W is open filtered by A2,
WAYBEL14:35;
      take J;
      let W be Subset of S;
      assume
A4:   W in J;
      then W is open by A3;
      hence thesis by A3,A4,WAYBEL11:def 4,YELLOW_8:12;
    end;
    hence N is with_open_semilattices by Th32;
    InclPoset sigma S is continuous by A2,WAYBEL14:36;
    hence InclPoset sigma N is continuous by A1,YELLOW_9:52;
  end;
  assume that
A5: N is with_open_semilattices and
A6: InclPoset sigma N is continuous;
A7: for x being Element of S ex J being Basis of x st for Y being Subset of
  S st Y in J holds Y is open filtered
  proof
    let x be Element of S;
    reconsider y = x as Element of N by A1;
    consider J being Basis of y such that
A8: for A being Subset of N st A in J holds subrelstr A is
    meet-inheriting by A5;
    reconsider J9 = {uparrow A where A is Subset of N: A in J} as Basis of x
    by Th16;
    take J9;
    let Y be Subset of S;
    assume
A9: Y in J9;
    then consider A being Subset of N such that
A10: Y = uparrow A and
A11: A in J;
    subrelstr A is meet-inheriting by A8,A11;
    then A is filtered by YELLOW12:26;
    hence thesis by A1,A9,A10,WAYBEL_0:4,YELLOW_8:12;
  end;
  sigma S = sigma N by A1,YELLOW_9:52;
  then
  for x being Element of S holds x = "\/" ({inf X where X is Subset of S:
  x in X & X in sigma S}, S) by A7,A6,WAYBEL14:37;
  then S is continuous by WAYBEL14:38;
  hence thesis by A1,YELLOW12:15;
end;

registration
  cluster continuous -> with_open_semilattices for
Lawson complete TopLattice;
  coherence by Th35;
end;

registration
  let N be continuous Lawson complete TopLattice;
  cluster InclPoset sigma N -> continuous;
  coherence by Th35;
end;

:: Theorem 2.13, p. 155,  1 => 3

theorem
  for N being continuous Lawson complete TopLattice holds N is compact
  Hausdorff topological_semilattice with_open_semilattices
proof
  let N be continuous Lawson complete TopLattice;
  thus N is compact Hausdorff;
  InclPoset sigma N is continuous;
  hence N is topological_semilattice by Th22;
  thus thesis;
end;

:: Theorem 2.13, p. 155,  3 => 3'

theorem
  for N being Hausdorff topological_semilattice with_open_semilattices
  Lawson complete TopLattice holds N is with_compact_semilattices
proof
  let N be Hausdorff topological_semilattice with_open_semilattices Lawson
  complete TopLattice;
  let x be Point of N;
  consider BO being Basis of x such that
A1: for A being Subset of N st A in BO holds subrelstr A is
  meet-inheriting by Def4;
  set BC = {Cl A where A is Subset of N: A in BO};
  BC c= bool the carrier of N
  proof
    let k be object;
    assume k in BC;
    then ex A being Subset of N st k = Cl A & A in BO;
    hence thesis;
  end;
  then reconsider BC as Subset-Family of N;
  BC is basis of x
  proof
    let S be a_neighborhood of x;
A2: Int S c= S by TOPS_1:16;
    x in Int S by CONNSP_2:def 1;
    then consider W being Subset of N such that
A3: W in BO and
A4: W c= Int S by YELLOW_8:13;
A5: W is open by A3,YELLOW_8:12;
    x in W by A3,YELLOW_8:12;
    then x in Int W by A5,TOPS_1:23;
    then reconsider T = W as a_neighborhood of x by CONNSP_2:def 1;
    per cases;
    suppose
A6:   W <> [#]N;
      x in W by A3,YELLOW_8:12;
      then {x} c= W by ZFMISC_1:31;
      then consider G being Subset of N such that
A7:   G is open and
A8:   {x} c= G and
A9:   Cl G c= W by A5,A6,CONNSP_2:20;
      x in G by A8,ZFMISC_1:31;
      then consider K being Subset of N such that
A10:  K in BO and
A11:  K c= G by A7,YELLOW_8:13;
A12:  K is open by A10,YELLOW_8:12;
A13:  Int K c= Int Cl K by PRE_TOPC:18,TOPS_1:19;
      x in K by A10,YELLOW_8:12;
      then x in Int K by A12,TOPS_1:23;
      then reconsider KK = Cl K as a_neighborhood of x by A13,CONNSP_2:def 1;
      take KK;
      thus KK in BC by A10;
      Cl K c= Cl G by A11,PRE_TOPC:19;
      then Cl K c= W by A9;
      then KK c= Int S by A4;
      hence thesis by A2;
    end;
    suppose
A14:  W = [#]N;
      take T;
      Cl [#]N = [#]N by TOPS_1:2;
      hence T in BC by A3,A14;
      thus thesis by A4,A2;
    end;
  end;
  then reconsider BC as basis of x;
  take BC;
  let A be Subset of N;
  assume A in BC;
  then consider C being Subset of N such that
A15: A = Cl C and
A16: C in BO;
  subrelstr C is meet-inheriting by A1,A16;
  hence subrelstr A is meet-inheriting by A15,Th31;
  thus thesis by A15,COMPTS_1:8;
end;

:: Theorem 2.13, p. 155,  3' => 4

theorem
  for N being meet-continuous Hausdorff Lawson complete TopLattice, x
being Element of N holds x = "\/"({inf V where V is Subset of N: x in V & V in
  lambda N},N)
proof
  let N be meet-continuous Hausdorff Lawson complete TopLattice, x be
  Element of N;
  set S = the Scott complete TopAugmentation of N;
A1: InclPoset sigma S is continuous by WAYBEL14:36;
A2: the RelStr of S = the RelStr of N by YELLOW_9:def 4;
  then reconsider y = x as Element of S;
  for y being Element of S ex J being Basis of y st for X being Subset of
  S st X in J holds X is open filtered by WAYBEL14:35;
  hence x = "\/" ({inf X where X is Subset of S: y in X & X in sigma S}, S) by
A1,WAYBEL14:37
    .= "\/" ({inf X where X is Subset of S: x in X & X in sigma S}, N) by A2,
YELLOW_0:17,26
    .= "\/" ({inf V where V is Subset of N: x in V & V in lambda N}, N) by Th34
;
end;

:: Theorem 2.13, p. 155,  1 <=> 4

theorem
  for N being meet-continuous Lawson complete TopLattice holds N is
continuous iff for x being Element of N holds x = "\/"({inf V where V is Subset
  of N: x in V & V in lambda N},N)
proof
  let N be meet-continuous Lawson complete TopLattice;
  set S = the complete Scott TopAugmentation of N;
A1: the RelStr of S = the RelStr of N by YELLOW_9:def 4;
  hereby
    assume
A2: N is continuous;
    then
A3: for x being Element of S ex J being Basis of x st for Y being Subset
    of S st Y in J holds Y is open filtered by WAYBEL14:35;
    let x be Element of N;
    InclPoset sigma S is continuous by A2,WAYBEL14:36;
    hence x = "\/" ({inf X where X is Subset of S: x in X & X in sigma S}, S )
    by A3,A1,WAYBEL14:37
      .= "\/" ({inf X where X is Subset of S: x in X & X in sigma S}, N) by A1,
YELLOW_0:17,26
      .= "\/"({inf V where V is Subset of N: x in V & V in lambda N},N) by Th34
;
  end;
  assume
A4: for x being Element of N holds x = "\/"({inf V where V is Subset of
N: x in V & V in lambda N},N);
  now
    let x be Element of S;
    thus x = "\/"({inf V where V is Subset of N: x in V & V in lambda N},N) by
A1,A4
      .= "\/"({inf V where V is Subset of S: x in V & V in sigma S},N) by A1
,Th34
      .= "\/"({inf V where V is Subset of S: x in V & V in sigma S},S) by A1,
YELLOW_0:17,26;
  end;
  then S is continuous by WAYBEL14:38;
  hence thesis by A1,YELLOW12:15;
end;

:: Exercise 2.16, p. 156,  1 <=> 2

theorem Th40:
  for N being meet-continuous Lawson complete TopLattice holds N
  is algebraic iff N is with_open_semilattices & InclPoset sigma N is algebraic
proof
  let N be meet-continuous Lawson complete TopLattice;
  set S = the Scott TopAugmentation of N;
A1: the RelStr of S = the RelStr of N by YELLOW_9:def 4;
  hereby
    assume
A2: N is algebraic;
    then reconsider M = N as algebraic LATTICE;
    M is continuous;
    hence N is with_open_semilattices;
    S is algebraic by A1,A2,WAYBEL_8:17;
    then
    ex K being Basis of S st K = {uparrow x where x is Element of S: x in
    the carrier of CompactSublatt S} by WAYBEL14:42;
    then InclPoset sigma S is algebraic by WAYBEL14:43;
    hence InclPoset sigma N is algebraic by A1,YELLOW_9:52;
  end;
  assume that
A3: N is with_open_semilattices and
A4: InclPoset sigma N is algebraic;
  reconsider T = InclPoset sigma N as algebraic LATTICE by A4;
  T is continuous;
  then N is continuous by A3,Th35;
  then
  for x being Element of S ex K being Basis of x st for Y being Subset of
  S st Y in K holds Y is open filtered by WAYBEL14:35;
  then
A5: for V being Element of InclPoset sigma S ex VV being Subset of
InclPoset sigma S st V = sup VV & for W being Element of InclPoset sigma S st W
  in VV holds W is co-prime by WAYBEL14:39;
  InclPoset sigma S is algebraic by A1,A4,YELLOW_9:52;
  then ex K being Basis of S st K = {uparrow x where x is Element of S: x in
  the carrier of CompactSublatt S} by A5,WAYBEL14:44;
  then S is algebraic by WAYBEL14:45;
  hence thesis by A1,WAYBEL_8:17;
end;

registration
  let N be meet-continuous algebraic Lawson complete TopLattice;
  cluster InclPoset sigma N -> algebraic;
  coherence by Th40;
end;