let L be Stone Lattice; latt (L,(Skeleton L)) is complemented
set P = Skeleton L;
A0:
( Bottom L in Skeleton L & Top L in Skeleton L )
by Lm1;
set LL = latt (L,(Skeleton L));
for b being Element of (latt (L,(Skeleton L))) ex a being Element of (latt (L,(Skeleton L))) st a is_a_complement_of b
proof
let b be
Element of
(latt (L,(Skeleton L)));
ex a being Element of (latt (L,(Skeleton L))) st a is_a_complement_of b
reconsider bb =
b as
Element of
L by FILTER_2:68;
set aa =
bb * ;
bb * in Skeleton L
;
then reconsider a =
bb * as
Element of
(latt (L,(Skeleton L))) by FILTER_2:72;
b in the
carrier of
(latt (L,(Skeleton L)))
;
then z1:
b in Skeleton L
by FILTER_2:72;
(bb *) "\/" bb =
(((bb *) *) *) "\/" bb
by z1, Th13
.=
(((bb *) *) *) "\/" ((bb *) *)
by z1, Th13
.=
Top L
by SatStone
;
then A1:
a "\/" b =
Top L
by FILTER_2:73
.=
Top (latt (L,(Skeleton L)))
by A0, ThC
;
(bb *) "/\" bb = Bottom L
by ThD;
then a "/\" b =
Bottom L
by FILTER_2:73
.=
Bottom (latt (L,(Skeleton L)))
by A0, ThB
;
hence
ex
a being
Element of
(latt (L,(Skeleton L))) st
a is_a_complement_of b
by LATTICES:def 18, A1;
verum
end;
hence
latt (L,(Skeleton L)) is complemented
by LATTICES:def 19; verum