let NT be normal NTopSpace; NTop2Top NT is normal
reconsider T = NTop2Top NT as non empty TopSpace ;
now for F1, F2 being Subset of T st F1 is closed & F2 is closed & F1 misses F2 holds
ex G1, G2 being Subset of T st
( G1 is open & G2 is open & F1 c= G1 & F2 c= G2 & G1 misses G2 )let F1,
F2 be
Subset of
T;
( F1 is closed & F2 is closed & F1 misses F2 implies ex G1, G2 being Subset of T st
( G1 is open & G2 is open & F1 c= G1 & F2 c= G2 & G1 misses G2 ) )assume that A1:
F1 is
closed
and A2:
F2 is
closed
and A3:
F1 misses F2
;
ex G1, G2 being Subset of T st
( G1 is open & G2 is open & F1 c= G1 & F2 c= G2 & G1 misses G2 )
Top2NTop T = NT
by FINTOPO7:25;
then reconsider F19 =
F1,
F29 =
F2 as
closed Subset of
NT by A1, A2, Lm7;
consider V being
a_neighborhood of
F19,
W being
a_neighborhood of
F29 such that A4:
V misses W
by A3, Def13;
A5:
(
NTop2Top F19 c= Int (NTop2Top V) &
NTop2Top F29 c= Int (NTop2Top W) )
by Th36, CONNSP_2:def 2;
reconsider G1 =
Int (NTop2Top V),
G2 =
Int (NTop2Top W) as
open Subset of
T ;
thus
ex
G1,
G2 being
Subset of
T st
(
G1 is
open &
G2 is
open &
F1 c= G1 &
F2 c= G2 &
G1 misses G2 )
by A4, A5, Th1;
verum end;
hence
NTop2Top NT is normal
by PRE_TOPC:def 12; verum