let X be set ; :: thesis: for p being Real
for f being PartFunc of REAL , REAL st X c= dom f & f | X is uniformly_continuous holds
(p (#) f) | X is uniformly_continuous
let p be Real; :: thesis: for f being PartFunc of REAL , REAL st X c= dom f & f | X is uniformly_continuous holds
(p (#) f) | X is uniformly_continuous
let f be PartFunc of REAL , REAL ; :: thesis: ( X c= dom f & f | X is uniformly_continuous implies (p (#) f) | X is uniformly_continuous )
assume
X c= dom f
; :: thesis: ( not f | X is uniformly_continuous or (p (#) f) | X is uniformly_continuous )
then A2:
X c= dom (p (#) f)
by VALUED_1:def 5;
assume A1:
f | X is uniformly_continuous
; :: thesis: (p (#) f) | X is uniformly_continuous
per cases
( p = 0 or p <> 0 )
;
suppose A3:
p = 0
;
:: thesis: (p (#) f) | X is uniformly_continuousnow let r be
Real;
:: thesis: ( 0 < r implies ex s being Real st
( 0 < s & ( for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r ) ) )assume A4:
0 < r
;
:: thesis: ex s being Real st
( 0 < s & ( for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r ) )then consider s being
Real such that A5:
(
0 < s & ( for
x1,
x2 being
Real st
x1 in dom (f | X) &
x2 in dom (f | X) &
abs (x1 - x2) < s holds
abs ((f . x1) - (f . x2)) < r ) )
by A1, Def1;
take s =
s;
:: thesis: ( 0 < s & ( for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r ) )thus
0 < s
by A5;
:: thesis: for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < rlet x1,
x2 be
Real;
:: thesis: ( x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s implies abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r )assume
(
x1 in dom ((p (#) f) | X) &
x2 in dom ((p (#) f) | X) &
abs (x1 - x2) < s )
;
:: thesis: abs (((p (#) f) . x1) - ((p (#) f) . x2)) < rthen B6:
(
x1 in X &
x2 in X )
by RELAT_1:86;
then abs (((p (#) f) . x1) - ((p (#) f) . x2)) =
abs ((p * (f . x1)) - ((p (#) f) . x2))
by A2, VALUED_1:def 5
.=
abs (0 - (p * (f . x2)))
by A2, A3, B6, VALUED_1:def 5
.=
0
by A3, ABSVALUE:7
;
hence
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r
by A4;
:: thesis: verum end; hence
(p (#) f) | X is
uniformly_continuous
by Def1;
:: thesis: verum end; suppose A7:
p <> 0
;
:: thesis: (p (#) f) | X is uniformly_continuousthen A8:
0 < abs p
by COMPLEX1:133;
A9:
0 <> abs p
by A7, COMPLEX1:133;
now let r be
Real;
:: thesis: ( 0 < r implies ex s being Real st
( 0 < s & ( for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r ) ) )assume
0 < r
;
:: thesis: ex s being Real st
( 0 < s & ( for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r ) )then
0 < r / (abs p)
by A8, XREAL_1:141;
then consider s being
Real such that A10:
(
0 < s & ( for
x1,
x2 being
Real st
x1 in dom (f | X) &
x2 in dom (f | X) &
abs (x1 - x2) < s holds
abs ((f . x1) - (f . x2)) < r / (abs p) ) )
by A1, Def1;
take s =
s;
:: thesis: ( 0 < s & ( for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r ) )thus
0 < s
by A10;
:: thesis: for x1, x2 being Real st x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s holds
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < rlet x1,
x2 be
Real;
:: thesis: ( x1 in dom ((p (#) f) | X) & x2 in dom ((p (#) f) | X) & abs (x1 - x2) < s implies abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r )assume A11:
(
x1 in dom ((p (#) f) | X) &
x2 in dom ((p (#) f) | X) &
abs (x1 - x2) < s )
;
:: thesis: abs (((p (#) f) . x1) - ((p (#) f) . x2)) < rthen B6:
(
x1 in X &
x2 in X )
by RELAT_1:86;
(
x1 in dom (p (#) f) &
x2 in dom (p (#) f) )
by A11, RELAT_1:86;
then
(
x1 in dom f &
x2 in dom f )
by VALUED_1:def 5;
then C6:
(
x1 in dom (f | X) &
x2 in dom (f | X) )
by B6, RELAT_1:86;
A12:
abs (((p (#) f) . x1) - ((p (#) f) . x2)) =
abs ((p * (f . x1)) - ((p (#) f) . x2))
by A2, B6, VALUED_1:def 5
.=
abs ((p * (f . x1)) - (p * (f . x2)))
by A2, B6, VALUED_1:def 5
.=
abs (p * ((f . x1) - (f . x2)))
.=
(abs p) * (abs ((f . x1) - (f . x2)))
by COMPLEX1:151
;
(abs p) * (abs ((f . x1) - (f . x2))) < (r / (abs p)) * (abs p)
by A8, A10, A11, C6, XREAL_1:70;
hence
abs (((p (#) f) . x1) - ((p (#) f) . x2)) < r
by A9, A12, XCMPLX_1:88;
:: thesis: verum end; hence
(p (#) f) | X is
uniformly_continuous
by Def1;
:: thesis: verum end; end;