let T be non empty strict normal TopSpace; Top2NTop T is normal
reconsider NT = Top2NTop T as NTopSpace ;
now for NA, NB being closed Subset of NT st NA misses NB holds
ex V being a_neighborhood of NA ex W being a_neighborhood of NB st V misses Wlet NA,
NB be
closed Subset of
NT;
( NA misses NB implies ex V being a_neighborhood of NA ex W being a_neighborhood of NB st V misses W )assume A1:
NA misses NB
;
ex V being a_neighborhood of NA ex W being a_neighborhood of NB st V misses W
NTop2Top NT = T
by FINTOPO7:24;
then reconsider A =
NTop2Top NA,
B =
NTop2Top NB as
closed Subset of
T by Lm29;
consider G1,
G2 being
Subset of
T such that A2:
G1 is
open
and A3:
G2 is
open
and A4:
A c= G1
and A5:
B c= G2
and A6:
G1 misses G2
by A1, PRE_TOPC:def 12;
reconsider V =
Top2NTop G1,
W =
Top2NTop G2 as
open Subset of
NT by Lm1, A2, A3;
A7:
(
A c= Int G1 &
B c= Int G2 )
by A2, A3, A4, A5, TOPS_1:23;
reconsider V =
G1,
W =
G2 as
open Subset of
NT by A2, A3, Lm1;
(
Top2NTop G1 is
a_neighborhood of
Top2NTop A &
Top2NTop G2 is
a_neighborhood of
Top2NTop B )
by A7, CONNSP_2:def 2, Lm31;
hence
ex
V being
a_neighborhood of
NA ex
W being
a_neighborhood of
NB st
V misses W
by A6;
verum end;
hence
Top2NTop T is normal
; verum