let X be set ; :: thesis: for E being Tolerance of X holds Web (CohSp E) = E
let E be Tolerance of X; :: thesis: Web (CohSp E) = E
now let x,
y be
set ;
:: thesis: ( ( [x,y] in Web (CohSp E) implies [x,y] in E ) & ( [x,y] in E implies [x,y] in Web (CohSp E) ) )thus
(
[x,y] in Web (CohSp E) implies
[x,y] in E )
:: thesis: ( [x,y] in E implies [x,y] in Web (CohSp E) )assume A2:
[x,y] in E
;
:: thesis: [x,y] in Web (CohSp E)then A3:
(
x in X &
y in X )
by ZFMISC_1:106;
for
u,
v being
set st
u in {x,y} &
v in {x,y} holds
[u,v] in E
proof
let u,
v be
set ;
:: thesis: ( u in {x,y} & v in {x,y} implies [u,v] in E )
assume
(
u in {x,y} &
v in {x,y} )
;
:: thesis: [u,v] in E
then
( (
u = x or
u = y ) & (
v = x or
v = y ) )
by TARSKI:def 2;
hence
[u,v] in E
by A2, A3, EQREL_1:12, TOLER_1:27;
:: thesis: verum
end; then
{x,y} in CohSp E
by Def4;
hence
[x,y] in Web (CohSp E)
by Th5;
:: thesis: verum end;
hence
Web (CohSp E) = E
by RELAT_1:def 2; :: thesis: verum