let m, n be Nat; for f being Function of (TOP-REAL m),(TOP-REAL n) st f is continuous holds
f (-) is continuous Function of (TOP-REAL m),(TOP-REAL n)
let f be Function of (TOP-REAL m),(TOP-REAL n); ( f is continuous implies f (-) is continuous Function of (TOP-REAL m),(TOP-REAL n) )
assume A1:
f is continuous
; f (-) is continuous Function of (TOP-REAL m),(TOP-REAL n)
reconsider g = f (-) as Function of (TOP-REAL m),(TOP-REAL n) by Th34;
for p being Point of (TOP-REAL m)
for r being real positive number ex s being real positive number st g .: (Ball p,s) c= Ball (g . p),r
proof
let p be
Point of
(TOP-REAL m);
for r being real positive number ex s being real positive number st g .: (Ball p,s) c= Ball (g . p),rlet r be
real positive number ;
ex s being real positive number st g .: (Ball p,s) c= Ball (g . p),r
consider s being
real positive number such that A2:
f .: (Ball (- p),s) c= Ball (f . (- p)),
r
by A1, TOPS_4:20;
take
s
;
g .: (Ball p,s) c= Ball (g . p),r
let y be
Element of
(TOP-REAL n);
LATTICE7:def 1 ( not y in g .: (Ball p,s) or y in Ball (g . p),r )
assume
y in g .: (Ball p,s)
;
y in Ball (g . p),r
then consider x being
Element of
(TOP-REAL m) such that A3:
x in Ball p,
s
and A4:
g . x = y
by FUNCT_2:116;
dom g = the
carrier of
(TOP-REAL m)
by FUNCT_2:def 1;
then A6:
(
g . x = f . (- x) &
g . p = f . (- p) )
by VALUED_2:def 34;
- x in Ball (- p),
s
by A3, Th23;
then
f . (- x) in f .: (Ball (- p),s)
by FUNCT_2:43;
hence
y in Ball (g . p),
r
by A2, A4, A6;
verum
end;
hence
f (-) is continuous Function of (TOP-REAL m),(TOP-REAL n)
by TOPS_4:20; verum