defpred S1[ Real, Real, set ] means ex c being Element of REAL 2 st
( c = $3 & $3 = <*$1,$2*> );
let A, B be compact Subset of REAL; product ((1,2) --> (A,B)) is compact Subset of (TOP-REAL 2)
reconsider X = product ((1,2) --> (A,B)) as Subset of (TOP-REAL 2) by Th20;
reconsider A1 = A, B1 = B as Subset of R^1 by TOPMETR:17;
A1:
the carrier of (TOP-REAL 2) = REAL 2
by EUCLID:22;
A2:
for x, y being Element of REAL ex u being Element of REAL 2 st S1[x,y,u]
proof
let x,
y be
Element of
REAL ;
ex u being Element of REAL 2 st S1[x,y,u]
take
<*x,y*>
;
( <*x,y*> is Element of REAL 2 & S1[x,y,<*x,y*>] )
thus
<*x,y*> is
Element of
REAL 2
by FINSEQ_2:137;
S1[x,y,<*x,y*>]
<*x,y*> in 2
-tuples_on REAL
by FINSEQ_2:137;
hence
S1[
x,
y,
<*x,y*>]
;
verum
end;
consider h being Function of [:REAL,REAL:],(REAL 2) such that
A3:
for x, y being Element of REAL holds S1[x,y,h . (x,y)]
from BINOP_1:sch 3(A2);
the carrier of [:R^1,R^1:] = [: the carrier of R^1, the carrier of R^1:]
by BORSUK_1:def 2;
then reconsider h = h as Function of [:R^1,R^1:],(TOP-REAL 2) by A1, TOPMETR:17;
A4:
for x, y being Real holds h . [x,y] = <*x,y*>
then A5:
h is being_homeomorphism
by Th69;
A6:
B1 is compact
by JORDAN5A:25;
A1 is compact
by JORDAN5A:25;
then A7:
[:A1,B1:] is compact
by A6, BORSUK_3:23;
h .: [:A1,B1:] = X
by A4, Th68;
hence
product ((1,2) --> (A,B)) is compact Subset of (TOP-REAL 2)
by A7, A5, WEIERSTR:8; verum