let S, T be complete LATTICE; :: thesis: for g being infs-preserving Function of S,T holds
( g is directed-sups-preserving iff for X being Scott TopAugmentation of T
for Y being Scott TopAugmentation of S
for V being open Subset of X holds uparrow ((LowerAdj g) .: V) is open Subset of Y )

let g be infs-preserving Function of S,T; :: thesis: ( g is directed-sups-preserving iff for X being Scott TopAugmentation of T
for Y being Scott TopAugmentation of S
for V being open Subset of X holds uparrow ((LowerAdj g) .: V) is open Subset of Y )

hereby :: thesis: ( ( for X being Scott TopAugmentation of T
for Y being Scott TopAugmentation of S
for V being open Subset of X holds uparrow ((LowerAdj g) .: V) is open Subset of Y ) implies g is directed-sups-preserving )
assume A1: g is directed-sups-preserving ; :: thesis: for X being Scott TopAugmentation of T
for Y being Scott TopAugmentation of S
for V being open Subset of X holds uparrow ((LowerAdj g) .: V) is open Subset of Y

let X be Scott TopAugmentation of T; :: thesis: for Y being Scott TopAugmentation of S
for V being open Subset of X holds uparrow ((LowerAdj g) .: V) is open Subset of Y

let Y be Scott TopAugmentation of S; :: thesis: for V being open Subset of X holds uparrow ((LowerAdj g) .: V) is open Subset of Y
let V be open Subset of X; :: thesis: uparrow ((LowerAdj g) .: V) is open Subset of Y
A2: ( RelStr(# the carrier of X,the InternalRel of X #) = RelStr(# the carrier of T,the InternalRel of T #) & RelStr(# the carrier of Y,the InternalRel of Y #) = RelStr(# the carrier of S,the InternalRel of S #) ) by YELLOW_9:def 4;
then reconsider g' = g as Function of Y,X ;
reconsider d = LowerAdj g as Function of X,Y by A2;
uparrow (d .: V) is inaccessible_by_directed_joins
proof
let D be non empty directed Subset of Y; :: according to WAYBEL11:def 1 :: thesis: ( not "\/" D,Y in uparrow (d .: V) or not D misses uparrow (d .: V) )
assume sup D in uparrow (d .: V) ; :: thesis: not D misses uparrow (d .: V)
then consider y being Element of Y such that
A3: ( y <= sup D & y in d .: V ) by WAYBEL_0:def 16;
consider u being set such that
A4: ( u in the carrier of X & u in V & y = d . u ) by A3, FUNCT_2:115;
reconsider u = u as Element of X by A4;
reconsider g = g' as Function of Y,X ;
[g,d] is Galois Connection of S,T by Def1;
then [g,d] is Galois by A2, Th1;
then A5: ( d * g <= id Y & id X <= g * d ) by WAYBEL_1:19;
A6: ( (id X) . u = u & (g * d) . u = g . (d . u) ) by FUNCT_1:35, FUNCT_2:21;
A7: g is infs-preserving Function of Y,X by A2, WAYBEL21:6;
then ( u <= g . y & g . y <= g . (sup D) ) by A3, A4, A5, A6, ORDERS_3:def 5, YELLOW_2:10;
then ( u <= g . (sup D) & V is upper ) by ORDERS_2:26, WAYBEL11:def 4;
then A8: g . (sup D) in V by A4, WAYBEL_0:def 20;
g is directed-sups-preserving by A1, A2, WAYBEL21:6;
then ( g preserves_sup_of D & ex_sup_of D,Y ) by WAYBEL_0:def 37, YELLOW_0:17;
then A9: g . (sup D) = sup (g .: D) by WAYBEL_0:def 31;
( g .: D is directed & not g .: D is empty & V is inaccessible_by_directed_joins ) by A7, WAYBEL11:def 4, YELLOW_2:17;
then g .: D meets V by A8, A9, WAYBEL11:def 1;
then consider z being set such that
A10: ( z in g .: D & z in V ) by XBOOLE_0:3;
consider x being set such that
A11: ( x in the carrier of Y & x in D & z = g . x ) by A10, FUNCT_2:115;
reconsider x = x as Element of Y by A11;
( (d * g) . x = d . (g . x) & (id Y) . x = x ) by FUNCT_1:35, FUNCT_2:21;
then ( d . (g . x) <= x & d . z in d .: V ) by A5, A10, FUNCT_2:43, YELLOW_2:10;
then x in uparrow (d .: V) by A11, WAYBEL_0:def 16;
hence not D misses uparrow (d .: V) by A11, XBOOLE_0:3; :: thesis: verum
end;
then uparrow (d .: V) is open Subset of Y by WAYBEL11:def 4;
hence uparrow ((LowerAdj g) .: V) is open Subset of Y by A2, WAYBEL_0:13; :: thesis: verum
end;
assume A12: for X being Scott TopAugmentation of T
for Y being Scott TopAugmentation of S
for V being open Subset of X holds uparrow ((LowerAdj g) .: V) is open Subset of Y ; :: thesis: g is directed-sups-preserving
consider X being Scott TopAugmentation of T, Y being Scott TopAugmentation of S;
A13: ( RelStr(# the carrier of X,the InternalRel of X #) = RelStr(# the carrier of T,the InternalRel of T #) & RelStr(# the carrier of Y,the InternalRel of Y #) = RelStr(# the carrier of S,the InternalRel of S #) ) by YELLOW_9:def 4;
then reconsider g' = g as Function of Y,X ;
reconsider g' = g' as infs-preserving Function of Y,X by A13, WAYBEL21:6;
set d = LowerAdj g;
reconsider d' = LowerAdj g as Function of X,Y by A13;
let D be Subset of S; :: according to WAYBEL_0:def 37 :: thesis: ( D is empty or not D is directed or g preserves_sup_of D )
assume A14: ( not D is empty & D is directed ) ; :: thesis: g preserves_sup_of D
assume ex_sup_of D,S ; :: according to WAYBEL_0:def 31 :: thesis: ( ex_sup_of g .: D,T & "\/" (g .: D),T = g . ("\/" D,S) )
thus ex_sup_of g .: D,T by YELLOW_0:17; :: thesis: "\/" (g .: D),T = g . ("\/" D,S)
A15: sup (g .: D) <= g . (sup D) by WAYBEL17:15;
reconsider D' = D as Subset of Y by A13;
reconsider D' = D' as non empty directed Subset of Y by A13, A14, WAYBEL_0:3;
reconsider s = sup D as Element of Y by A13;
set U' = (downarrow (sup (g' .: D'))) ` ;
A16: (downarrow (sup (g' .: D'))) ` is open by WAYBEL11:12;
then uparrow ((LowerAdj g) .: ((downarrow (sup (g' .: D'))) ` )) is open Subset of Y by A12;
then A17: uparrow ((LowerAdj g) .: ((downarrow (sup (g' .: D'))) ` )) is upper inaccessible Subset of Y by WAYBEL11:def 4;
A18: ex_sup_of g .: D,T by YELLOW_0:17;
then sup (g' .: D') = sup (g .: D) by A13, YELLOW_0:26;
then A19: downarrow (sup (g' .: D')) = downarrow (sup (g .: D)) by A13, WAYBEL_0:13;
A20: sup (g .: D) <= sup (g .: D) ;
[g,(LowerAdj g)] is Galois by Def1;
then A21: ( (LowerAdj g) * g <= id S & id T <= g * (LowerAdj g) ) by WAYBEL_1:19;
( (id S) . (sup D) = sup D & ((LowerAdj g) * g) . (sup D) = (LowerAdj g) . (g . (sup D)) ) by FUNCT_1:35, FUNCT_2:21;
then (LowerAdj g) . (g . (sup D)) <= sup D by A21, YELLOW_2:10;
then A22: d' . (g' . s) <= s by A13, YELLOW_0:1;
ex_sup_of D,S by YELLOW_0:17;
then A23: s = sup D' by A13, YELLOW_0:26;
g . (sup D) <= sup (g .: D)
proof
assume not g . (sup D) <= sup (g .: D) ; :: thesis: contradiction
then ( not g . (sup D) in downarrow (sup (g .: D)) & sup (g .: D) in downarrow (sup (g .: D)) ) by A20, WAYBEL_0:17;
then A24: ( g . (sup D) in (downarrow (sup (g' .: D'))) ` & not sup (g .: D) in (downarrow (sup (g' .: D'))) ` ) by A13, A19, XBOOLE_0:def 5;
then ( d' . (g' . s) in d' .: ((downarrow (sup (g' .: D'))) ` ) & d' .: ((downarrow (sup (g' .: D'))) ` ) c= uparrow (d' .: ((downarrow (sup (g' .: D'))) ` )) ) by FUNCT_2:43, WAYBEL_0:16;
then ( s in uparrow (d' .: ((downarrow (sup (g' .: D'))) ` )) & uparrow (d' .: ((downarrow (sup (g' .: D'))) ` )) = uparrow ((LowerAdj g) .: ((downarrow (sup (g' .: D'))) ` )) ) by A13, A22, WAYBEL_0:13, WAYBEL_0:def 20;
then D' meets uparrow (d' .: ((downarrow (sup (g' .: D'))) ` )) by A17, A23, WAYBEL11:def 1;
then consider x being set such that
A25: ( x in D' & x in uparrow (d' .: ((downarrow (sup (g' .: D'))) ` )) ) by XBOOLE_0:3;
reconsider x = x as Element of Y by A25;
consider u' being Element of Y such that
A26: ( u' <= x & u' in d' .: ((downarrow (sup (g' .: D'))) ` ) ) by A25, WAYBEL_0:def 16;
consider u being set such that
A27: ( u in the carrier of X & u in (downarrow (sup (g' .: D'))) ` & u' = d' . u ) by A26, FUNCT_2:115;
reconsider u = u as Element of X by A27;
reconsider a = u as Element of T by A13;
(id T) . a = u by FUNCT_1:35;
then a <= (g * (LowerAdj g)) . a by A21, YELLOW_2:10;
then a <= g . ((LowerAdj g) . a) by FUNCT_2:21;
then ( u <= g' . (d' . u) & g' . (d' . u) <= g' . x ) by A13, A26, A27, ORDERS_3:def 5, YELLOW_0:1;
then A28: u <= g' . x by ORDERS_2:26;
g' . x in g' .: D' by A25, FUNCT_2:43;
then g' . x <= sup (g' .: D') by YELLOW_2:24;
then ( u <= sup (g' .: D') & (downarrow (sup (g' .: D'))) ` is upper ) by A16, A28, ORDERS_2:26, WAYBEL11:def 4;
then sup (g' .: D') in (downarrow (sup (g' .: D'))) ` by A27, WAYBEL_0:def 20;
hence contradiction by A13, A18, A24, YELLOW_0:26; :: thesis: verum
end;
hence "\/" (g .: D),T = g . ("\/" D,S) by A15, ORDERS_2:25; :: thesis: verum