let T be TopSpace; ( T is T_1 & ( for A, B being closed Subset of T st A misses B holds
ex A9, B9 being closed Subset of T st
( A9 misses B9 & A9 \/ B9 = [#] T & A c= A9 & B c= B9 ) ) implies ( T is finite-ind & ind T <= 0 ) )
assume A1:
( T is T_1 & ( for A, B being closed Subset of T st A misses B holds
ex A9, B9 being closed Subset of T st
( A9 misses B9 & A9 \/ B9 = [#] T & A c= A9 & B c= B9 ) ) )
; ( T is finite-ind & ind T <= 0 )
A2:
now for p being Point of T
for U being open Subset of T st p in U holds
ex W being open Subset of T st
( p in W & W c= U & Fr W is finite-ind & ind (Fr W) <= 0 - 1 )let p be
Point of
T;
for U being open Subset of T st p in U holds
ex W being open Subset of T st
( p in W & W c= U & Fr W is finite-ind & ind (Fr W) <= 0 - 1 )let U be
open Subset of
T;
( p in U implies ex W being open Subset of T st
( p in W & W c= U & Fr W is finite-ind & ind (Fr W) <= 0 - 1 ) )assume A3:
p in U
;
ex W being open Subset of T st
( p in W & W c= U & Fr W is finite-ind & ind (Fr W) <= 0 - 1 )reconsider P =
{p} as
Subset of
T by A3, ZFMISC_1:31;
not
p in U `
by A3, XBOOLE_0:def 5;
then A4:
P misses U `
by ZFMISC_1:50;
not
T is
empty
by A3;
then consider A9,
B9 being
closed Subset of
T such that A5:
A9 misses B9
and A6:
A9 \/ B9 = [#] T
and A7:
P c= A9
and A8:
U ` c= B9
by A1, A4;
reconsider W =
B9 ` as
open Subset of
T ;
take W =
W;
( p in W & W c= U & Fr W is finite-ind & ind (Fr W) <= 0 - 1 )
p in P
by TARSKI:def 1;
then
(
(U `) ` = U & not
p in B9 )
by A5, A7, XBOOLE_0:3;
hence
(
p in W &
W c= U )
by A3, A8, SUBSET_1:12, XBOOLE_0:def 5;
( Fr W is finite-ind & ind (Fr W) <= 0 - 1 )
B9 = A9 `
by A5, A6, PRE_TOPC:5;
then
Fr B9 = {} T
by TOPGEN_1:14;
hence
(
Fr W is
finite-ind &
ind (Fr W) <= 0 - 1 )
by Th6;
verum end;
then
T is finite-ind
by Th15;
hence
( T is finite-ind & ind T <= 0 )
by A2, Th16; verum