let TS be TopSpace; :: thesis: ( TS is Hausdorff implies for A being Subset of TS st A <> {} & A is compact holds
for p being Point of TS st p in A ` holds
ex PS, QS being Subset of TS st
( PS is open & QS is open & p in PS & A c= QS & PS misses QS ) )

assume A1: TS is Hausdorff ; :: thesis: for A being Subset of TS st A <> {} & A is compact holds
for p being Point of TS st p in A ` holds
ex PS, QS being Subset of TS st
( PS is open & QS is open & p in PS & A c= QS & PS misses QS )

let F be Subset of TS; :: thesis: ( F <> {} & F is compact implies for p being Point of TS st p in F ` holds
ex PS, QS being Subset of TS st
( PS is open & QS is open & p in PS & F c= QS & PS misses QS ) )

assume that
A2: F <> {} and
A3: F is compact ; :: thesis: for p being Point of TS st p in F ` holds
ex PS, QS being Subset of TS st
( PS is open & QS is open & p in PS & F c= QS & PS misses QS )

let a be Point of TS; :: thesis: ( a in F ` implies ex PS, QS being Subset of TS st
( PS is open & QS is open & a in PS & F c= QS & PS misses QS ) )

assume A4: a in F ` ; :: thesis: ex PS, QS being Subset of TS st
( PS is open & QS is open & a in PS & F c= QS & PS misses QS )

A5: not a in F by A4, XBOOLE_0:def 5;
defpred S1[ set , set , set ] means ex PS, QS being Subset of TS st
( $2 = PS & $3 = QS & PS is open & QS is open & a in PS & $1 in QS & PS /\ QS = {} );
A6: for x being set st x in F holds
ex y, z being set st
( y in the topology of TS & z in the topology of TS & S1[x,y,z] )
proof
let x be set ; :: thesis: ( x in F implies ex y, z being set st
( y in the topology of TS & z in the topology of TS & S1[x,y,z] ) )

assume A7: x in F ; :: thesis: ex y, z being set st
( y in the topology of TS & z in the topology of TS & S1[x,y,z] )

then reconsider p = x as Point of TS ;
consider W, V being Subset of TS such that
A8: W is open and
A9: V is open and
A10: a in W and
A11: p in V and
A12: W misses V by A1, A5, A7, PRE_TOPC:def 16;
reconsider PS = W, QS = V as set ;
take PS ; :: thesis: ex z being set st
( PS in the topology of TS & z in the topology of TS & S1[x,PS,z] )

take QS ; :: thesis: ( PS in the topology of TS & QS in the topology of TS & S1[x,PS,QS] )
thus ( PS in the topology of TS & QS in the topology of TS ) by A8, A9, PRE_TOPC:def 5; :: thesis: S1[x,PS,QS]
take W ; :: thesis: ex QS being Subset of TS st
( PS = W & QS = QS & W is open & QS is open & a in W & x in QS & W /\ QS = {} )

take V ; :: thesis: ( PS = W & QS = V & W is open & V is open & a in W & x in V & W /\ V = {} )
thus ( PS = W & QS = V & W is open & V is open & a in W & x in V & W /\ V = {} ) by A8, A9, A10, A11, A12, XBOOLE_0:def 7; :: thesis: verum
end;
consider f, g being Function such that
A13: ( dom f = F & dom g = F ) and
A14: for x being set st x in F holds
S1[x,f . x,g . x] from WELLORD2:sch 2(A6);
g .: F c= bool the carrier of TS
proof
let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in g .: F or x in bool the carrier of TS )
assume x in g .: F ; :: thesis: x in bool the carrier of TS
then consider y being set such that
y in dom g and
A15: y in F and
A16: g . y = x by FUNCT_1:def 12;
ex PS, QS being Subset of TS st
( f . y = PS & g . y = QS & PS is open & QS is open & a in PS & y in QS & PS /\ QS = {} ) by A14, A15;
hence x in bool the carrier of TS by A16; :: thesis: verum
end;
then reconsider C = g .: F as Subset-Family of TS ;
F c= union C
proof
let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in F or x in union C )
assume A17: x in F ; :: thesis: x in union C
then consider PS, QS being Subset of TS such that
f . x = PS and
A18: g . x = QS and
PS is open and
QS is open and
a in PS and
A19: x in QS and
PS /\ QS = {} by A14;
QS in C by A13, A17, A18, FUNCT_1:def 12;
hence x in union C by A19, TARSKI:def 4; :: thesis: verum
end;
then A20: C is Cover of F by SETFAM_1:def 12;
A21: C is open
proof
let G be Subset of TS; :: according to TOPS_2:def 1 :: thesis: ( not G in C or G is open )
assume G in C ; :: thesis: G is open
then consider x being set such that
x in dom g and
A22: x in F and
A23: G = g . x by FUNCT_1:def 12;
ex PS, QS being Subset of TS st
( f . x = PS & g . x = QS & PS is open & QS is open & a in PS & x in QS & PS /\ QS = {} ) by A14, A22;
hence G is open by A23; :: thesis: verum
end;
then consider C' being Subset-Family of TS such that
A24: C' c= C and
A25: C' is Cover of F and
A26: C' is finite by A3, A20, Def7;
C' c= rng g by A13, A24, RELAT_1:146;
then consider H' being set such that
A27: H' c= dom g and
A28: H' is finite and
A29: g .: H' = C' by A26, ORDERS_1:195;
f .: H' c= bool the carrier of TS
proof
let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in f .: H' or x in bool the carrier of TS )
assume x in f .: H' ; :: thesis: x in bool the carrier of TS
then consider y being set such that
y in dom f and
A30: y in H' and
A31: f . y = x by FUNCT_1:def 12;
ex PS, QS being Subset of TS st
( f . y = PS & g . y = QS & PS is open & QS is open & a in PS & y in QS & PS /\ QS = {} ) by A13, A14, A27, A30;
hence x in bool the carrier of TS by A31; :: thesis: verum
end;
then reconsider B = f .: H' as Subset-Family of TS ;
take G0 = meet B; :: thesis: ex QS being Subset of TS st
( G0 is open & QS is open & a in G0 & F c= QS & G0 misses QS )

take G1 = union C'; :: thesis: ( G0 is open & G1 is open & a in G0 & F c= G1 & G0 misses G1 )
B is open
proof
let G be Subset of TS; :: according to TOPS_2:def 1 :: thesis: ( not G in B or G is open )
assume G in B ; :: thesis: G is open
then consider x being set such that
A33: x in dom f and
x in H' and
A34: G = f . x by FUNCT_1:def 12;
ex PS, QS being Subset of TS st
( f . x = PS & g . x = QS & PS is open & QS is open & a in PS & x in QS & PS /\ QS = {} ) by A13, A14, A33;
hence G is open by A34; :: thesis: verum
end;
hence G0 is open by A28, TOPS_2:27; :: thesis: ( G1 is open & a in G0 & F c= G1 & G0 misses G1 )
thus G1 is open by A21, A24, TOPS_2:18, TOPS_2:26; :: thesis: ( a in G0 & F c= G1 & G0 misses G1 )
consider z being Element of F;
F c= union C' by A25, SETFAM_1:def 12;
then z in union C' by A2, TARSKI:def 3;
then consider D being set such that
z in D and
A35: D in C' by TARSKI:def 4;
reconsider D' = D as Subset of TS by A35;
consider y being set such that
A36: y in dom g and
A37: y in H' and
D' = g . y by A29, A35, FUNCT_1:def 12;
consider PS, QS being Subset of TS such that
A38: f . y = PS and
g . y = QS and
PS is open and
QS is open and
a in PS and
y in QS and
PS /\ QS = {} by A13, A14, A36;
A39: B <> {} by A13, A36, A37, A38, FUNCT_1:def 12;
for G being set st G in B holds
a in G
proof
let G be set ; :: thesis: ( G in B implies a in G )
assume A40: G in B ; :: thesis: a in G
then reconsider G' = G as Subset of TS ;
consider x being set such that
A41: x in dom f and
x in H' and
A42: G' = f . x by A40, FUNCT_1:def 12;
ex PS, QS being Subset of TS st
( f . x = PS & g . x = QS & PS is open & QS is open & a in PS & x in QS & PS /\ QS = {} ) by A13, A14, A41;
hence a in G by A42; :: thesis: verum
end;
hence a in G0 by A39, SETFAM_1:def 1; :: thesis: ( F c= G1 & G0 misses G1 )
thus F c= G1 by A25, SETFAM_1:def 12; :: thesis: G0 misses G1
thus G0 /\ G1 = {} :: according to XBOOLE_0:def 7 :: thesis: verum
proof
assume A43: G0 /\ G1 <> {} ; :: thesis: contradiction
consider x being Element of (meet B) /\ (union C');
A44: ( x in union C' & x in meet B ) by A43, XBOOLE_0:def 4;
then consider A being set such that
A45: x in A and
A46: A in C' by TARSKI:def 4;
consider z being set such that
A47: z in dom g and
A48: z in H' and
A49: A = g . z by A29, A46, FUNCT_1:def 12;
consider PS, QS being Subset of TS such that
A50: f . z = PS and
A51: g . z = QS and
PS is open and
QS is open and
a in PS and
z in QS and
A52: PS /\ QS = {} by A13, A14, A47;
PS in B by A13, A47, A48, A50, FUNCT_1:def 12;
then ( x in QS & x in PS ) by A44, A45, A49, A51, SETFAM_1:def 1;
hence contradiction by A52, XBOOLE_0:def 4; :: thesis: verum
end;