let X be set ; :: thesis: for RNS being RealNormSpace
for CNS being ComplexNormSpace
for f being PartFunc of RNS,CNS st f is_uniformly_continuous_on X holds
||.f.|| is_uniformly_continuous_on X
let RNS be RealNormSpace; :: thesis: for CNS being ComplexNormSpace
for f being PartFunc of RNS,CNS st f is_uniformly_continuous_on X holds
||.f.|| is_uniformly_continuous_on X
let CNS be ComplexNormSpace; :: thesis: for f being PartFunc of RNS,CNS st f is_uniformly_continuous_on X holds
||.f.|| is_uniformly_continuous_on X
let f be PartFunc of RNS,CNS; :: thesis: ( f is_uniformly_continuous_on X implies ||.f.|| is_uniformly_continuous_on X )
assume A1:
f is_uniformly_continuous_on X
; :: thesis: ||.f.|| is_uniformly_continuous_on X
then
X c= dom f
by Def3;
then A2:
X c= dom ||.f.||
by NCFCONT1:def 4;
for r being Real st 0 < r holds
ex s being Real st
( 0 < s & ( for x1, x2 being Point of RNS st x1 in X & x2 in X & ||.(x1 - x2).|| < s holds
abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r ) )
proof
let r be
Real;
:: thesis: ( 0 < r implies ex s being Real st
( 0 < s & ( for x1, x2 being Point of RNS st x1 in X & x2 in X & ||.(x1 - x2).|| < s holds
abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r ) ) )
assume
0 < r
;
:: thesis: ex s being Real st
( 0 < s & ( for x1, x2 being Point of RNS st x1 in X & x2 in X & ||.(x1 - x2).|| < s holds
abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r ) )
then consider s being
Real such that A3:
(
0 < s & ( for
x1,
x2 being
Point of
RNS st
x1 in X &
x2 in X &
||.(x1 - x2).|| < s holds
||.((f /. x1) - (f /. x2)).|| < r ) )
by A1, Def3;
take
s
;
:: thesis: ( 0 < s & ( for x1, x2 being Point of RNS st x1 in X & x2 in X & ||.(x1 - x2).|| < s holds
abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r ) )
thus
0 < s
by A3;
:: thesis: for x1, x2 being Point of RNS st x1 in X & x2 in X & ||.(x1 - x2).|| < s holds
abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r
let x1,
x2 be
Point of
RNS;
:: thesis: ( x1 in X & x2 in X & ||.(x1 - x2).|| < s implies abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r )
assume A4:
(
x1 in X &
x2 in X &
||.(x1 - x2).|| < s )
;
:: thesis: abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r
then abs ((||.f.|| /. x1) - (||.f.|| /. x2)) =
abs ((||.f.|| . x1) - (||.f.|| /. x2))
by A2, PARTFUN1:def 8
.=
abs ((||.f.|| . x1) - (||.f.|| . x2))
by A2, A4, PARTFUN1:def 8
.=
abs (||.(f /. x1).|| - (||.f.|| . x2))
by A2, A4, NCFCONT1:def 4
.=
abs (||.(f /. x1).|| - ||.(f /. x2).||)
by A2, A4, NCFCONT1:def 4
;
then A5:
abs ((||.f.|| /. x1) - (||.f.|| /. x2)) <= ||.((f /. x1) - (f /. x2)).||
by CLVECT_1:111;
||.((f /. x1) - (f /. x2)).|| < r
by A3, A4;
hence
abs ((||.f.|| /. x1) - (||.f.|| /. x2)) < r
by A5, XXREAL_0:2;
:: thesis: verum
end;
hence
||.f.|| is_uniformly_continuous_on X
by A2, NFCONT_2:def 2; :: thesis: verum