let S be non empty compact TopSpace; for T being non empty MetrSpace
for f, g being Function of S,(TopSpaceMetr T) st f is continuous & g is continuous holds
for Dist being RealMap of S st ( for x being Point of S holds Dist . x = dist ((In ((f . x),T)),(In ((g . x),T))) ) holds
( rng Dist <> {} & rng Dist is bounded_above & rng Dist is bounded_below )
let T be non empty MetrSpace; for f, g being Function of S,(TopSpaceMetr T) st f is continuous & g is continuous holds
for Dist being RealMap of S st ( for x being Point of S holds Dist . x = dist ((In ((f . x),T)),(In ((g . x),T))) ) holds
( rng Dist <> {} & rng Dist is bounded_above & rng Dist is bounded_below )
let f, g be Function of S,(TopSpaceMetr T); ( f is continuous & g is continuous implies for Dist being RealMap of S st ( for x being Point of S holds Dist . x = dist ((In ((f . x),T)),(In ((g . x),T))) ) holds
( rng Dist <> {} & rng Dist is bounded_above & rng Dist is bounded_below ) )
assume that
A1:
f is continuous
and
A2:
g is continuous
; for Dist being RealMap of S st ( for x being Point of S holds Dist . x = dist ((In ((f . x),T)),(In ((g . x),T))) ) holds
( rng Dist <> {} & rng Dist is bounded_above & rng Dist is bounded_below )
let Dist be RealMap of S; ( ( for x being Point of S holds Dist . x = dist ((In ((f . x),T)),(In ((g . x),T))) ) implies ( rng Dist <> {} & rng Dist is bounded_above & rng Dist is bounded_below ) )
assume A3:
for x being Point of S holds Dist . x = dist ((In ((f . x),T)),(In ((g . x),T)))
; ( rng Dist <> {} & rng Dist is bounded_above & rng Dist is bounded_below )
S is pseudocompact
;
then
Dist is bounded
by A1, A2, A3, Th8;
then A5:
( Dist is bounded_above & Dist is bounded_below )
;
thus
rng Dist <> {}
by FUNCT_2:112; ( rng Dist is bounded_above & rng Dist is bounded_below )
consider K being Real such that
A6:
for t being object st t in dom Dist holds
Dist . t < K
by A5;
then
K is UpperBound of rng Dist
by XXREAL_2:def 1;
hence
rng Dist is bounded_above
; rng Dist is bounded_below
consider K being Real such that
A8:
for t being object st t in dom Dist holds
K < Dist . t
by A5;
then
K is LowerBound of rng Dist
by XXREAL_2:def 2;
hence
rng Dist is bounded_below
; verum