let X, X1, Z, Z1 be set ; :: thesis: for f1, f2 being PartFunc of REAL ,REAL st X c= dom f1 & X1 c= dom f2 & f1 | X is uniformly_continuous & f2 | X1 is uniformly_continuous & f1 | Z is bounded & f2 | Z1 is bounded holds
(f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1) is uniformly_continuous
let f1, f2 be PartFunc of REAL ,REAL ; :: thesis: ( X c= dom f1 & X1 c= dom f2 & f1 | X is uniformly_continuous & f2 | X1 is uniformly_continuous & f1 | Z is bounded & f2 | Z1 is bounded implies (f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1) is uniformly_continuous )
assume that
Z1:
X c= dom f1
and
Z2:
X1 c= dom f2
; :: thesis: ( not f1 | X is uniformly_continuous or not f2 | X1 is uniformly_continuous or not f1 | Z is bounded or not f2 | Z1 is bounded or (f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1) is uniformly_continuous )
assume that
A1:
f1 | X is uniformly_continuous
and
A2:
f2 | X1 is uniformly_continuous
and
A3:
f1 | Z is bounded
and
A4:
f2 | Z1 is bounded
; :: thesis: (f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1) is uniformly_continuous
A5:
X c= dom f1
by Z1;
A6:
X1 c= dom f2
by Z2;
consider x1 being real number such that
A9:
for r being set st r in Z /\ (dom f1) holds
abs (f1 . r) <= x1
by A3, RFUNCT_1:90;
consider x2 being real number such that
A10:
for r being set st r in Z1 /\ (dom f2) holds
abs (f2 . r) <= x2
by A4, RFUNCT_1:90;
reconsider x1 = x1, x2 = x2 as Real by XREAL_0:def 1;
A11:
0 + 0 < (abs x1) + 1
by COMPLEX1:132, XREAL_1:10;
A12:
0 + 0 < (abs x2) + 1
by COMPLEX1:132, XREAL_1:10;
set M1 = (abs x1) + 1;
set M2 = (abs x2) + 1;
set M = max ((abs x1) + 1),((abs x2) + 1);
A13:
now let r be
Real;
:: thesis: ( r in ((X /\ Z) /\ X1) /\ Z1 implies ( abs (f1 . r) < max ((abs x1) + 1),((abs x2) + 1) & abs (f2 . r) < max ((abs x1) + 1),((abs x2) + 1) ) )assume
r in ((X /\ Z) /\ X1) /\ Z1
;
:: thesis: ( abs (f1 . r) < max ((abs x1) + 1),((abs x2) + 1) & abs (f2 . r) < max ((abs x1) + 1),((abs x2) + 1) )then A14:
r in (X /\ Z) /\ (X1 /\ Z1)
by XBOOLE_1:16;
then
r in X /\ Z
by XBOOLE_0:def 4;
then
(
r in X &
r in Z )
by XBOOLE_0:def 4;
then
r in Z /\ (dom f1)
by A5, XBOOLE_0:def 4;
then A15:
abs (f1 . r) <= x1
by A9;
x1 + 0 < (abs x1) + 1
by ABSVALUE:11, XREAL_1:10;
then A16:
abs (f1 . r) < (abs x1) + 1
by A15, XXREAL_0:2;
(abs x1) + 1
<= max ((abs x1) + 1),
((abs x2) + 1)
by XXREAL_0:25;
hence
abs (f1 . r) < max ((abs x1) + 1),
((abs x2) + 1)
by A16, XXREAL_0:2;
:: thesis: abs (f2 . r) < max ((abs x1) + 1),((abs x2) + 1)
r in X1 /\ Z1
by A14, XBOOLE_0:def 4;
then
(
r in X1 &
r in Z1 )
by XBOOLE_0:def 4;
then
r in Z1 /\ (dom f2)
by A6, XBOOLE_0:def 4;
then A17:
abs (f2 . r) <= x2
by A10;
x2 + 0 < (abs x2) + 1
by ABSVALUE:11, XREAL_1:10;
then A18:
abs (f2 . r) < (abs x2) + 1
by A17, XXREAL_0:2;
(abs x2) + 1
<= max ((abs x1) + 1),
((abs x2) + 1)
by XXREAL_0:25;
hence
abs (f2 . r) < max ((abs x1) + 1),
((abs x2) + 1)
by A18, XXREAL_0:2;
:: thesis: verum end;
A19:
0 < max ((abs x1) + 1),((abs x2) + 1)
by A11, A12, XXREAL_0:16;
then A20:
0 < 2 * (max ((abs x1) + 1),((abs x2) + 1))
by XREAL_1:131;
for r being Real st 0 < r holds
ex s being Real st
( 0 < s & ( for x1, x2 being Real st x1 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & x2 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & abs (x1 - x2) < s holds
abs (((f1 (#) f2) . x1) - ((f1 (#) f2) . x2)) < r ) )
proof
let r be
Real;
:: thesis: ( 0 < r implies ex s being Real st
( 0 < s & ( for x1, x2 being Real st x1 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & x2 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & abs (x1 - x2) < s holds
abs (((f1 (#) f2) . x1) - ((f1 (#) f2) . x2)) < r ) ) )
assume
0 < r
;
:: thesis: ex s being Real st
( 0 < s & ( for x1, x2 being Real st x1 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & x2 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & abs (x1 - x2) < s holds
abs (((f1 (#) f2) . x1) - ((f1 (#) f2) . x2)) < r ) )
then A21:
0 < r / (2 * (max ((abs x1) + 1),((abs x2) + 1)))
by A20, XREAL_1:141;
then consider s being
Real such that A22:
(
0 < s & ( for
x1,
x2 being
Real st
x1 in dom (f1 | X) &
x2 in dom (f1 | X) &
abs (x1 - x2) < s holds
abs ((f1 . x1) - (f1 . x2)) < r / (2 * (max ((abs x1) + 1),((abs x2) + 1))) ) )
by A1, Def1;
consider g being
Real such that A23:
(
0 < g & ( for
x1,
x2 being
Real st
x1 in dom (f2 | X1) &
x2 in dom (f2 | X1) &
abs (x1 - x2) < g holds
abs ((f2 . x1) - (f2 . x2)) < r / (2 * (max ((abs x1) + 1),((abs x2) + 1))) ) )
by A2, A21, Def1;
take p =
min s,
g;
:: thesis: ( 0 < p & ( for x1, x2 being Real st x1 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & x2 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & abs (x1 - x2) < p holds
abs (((f1 (#) f2) . x1) - ((f1 (#) f2) . x2)) < r ) )
thus
0 < p
by A22, A23, XXREAL_0:15;
:: thesis: for x1, x2 being Real st x1 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & x2 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & abs (x1 - x2) < p holds
abs (((f1 (#) f2) . x1) - ((f1 (#) f2) . x2)) < r
let y1,
y2 be
Real;
:: thesis: ( y1 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & y2 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) & abs (y1 - y2) < p implies abs (((f1 (#) f2) . y1) - ((f1 (#) f2) . y2)) < r )
assume
(
y1 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) &
y2 in dom ((f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1)) )
;
:: thesis: ( not abs (y1 - y2) < p or abs (((f1 (#) f2) . y1) - ((f1 (#) f2) . y2)) < r )
then A24:
(
y1 in ((X /\ Z) /\ X1) /\ Z1 &
y2 in ((X /\ Z) /\ X1) /\ Z1 )
by RELAT_1:86;
assume Z:
abs (y1 - y2) < p
;
:: thesis: abs (((f1 (#) f2) . y1) - ((f1 (#) f2) . y2)) < r
(
y1 in (X /\ Z) /\ (X1 /\ Z1) &
y2 in (X /\ Z) /\ (X1 /\ Z1) )
by A24, XBOOLE_1:16;
then
(
y1 in X /\ Z &
y1 in X1 /\ Z1 &
y2 in X /\ Z &
y2 in X1 /\ Z1 )
by XBOOLE_0:def 4;
then A25:
(
y1 in X &
y1 in X1 &
y2 in X &
y2 in X1 )
by XBOOLE_0:def 4;
(
p <= s &
p <= g )
by XXREAL_0:17;
then A26:
(
abs (y1 - y2) < s &
abs (y1 - y2) < g )
by Z, XXREAL_0:2;
abs (((f1 (#) f2) . y1) - ((f1 (#) f2) . y2)) =
abs (((f1 . y1) * (f2 . y1)) - ((f1 (#) f2) . y2))
by VALUED_1:5
.=
abs ((((f1 . y1) * (f2 . y1)) + (((f1 . y1) * (f2 . y2)) - ((f1 . y1) * (f2 . y2)))) - ((f1 . y2) * (f2 . y2)))
by VALUED_1:5
.=
abs (((f1 . y1) * ((f2 . y1) - (f2 . y2))) + (((f1 . y1) - (f1 . y2)) * (f2 . y2)))
;
then A27:
abs (((f1 (#) f2) . y1) - ((f1 (#) f2) . y2)) <= (abs ((f1 . y1) * ((f2 . y1) - (f2 . y2)))) + (abs (((f1 . y1) - (f1 . y2)) * (f2 . y2)))
by COMPLEX1:142;
A28:
abs ((f1 . y1) * ((f2 . y1) - (f2 . y2))) = (abs (f1 . y1)) * (abs ((f2 . y1) - (f2 . y2)))
by COMPLEX1:151;
(
y1 in dom (f2 | X1) &
y2 in dom (f2 | X1) )
by A25, Z2, RELAT_1:91;
then A29:
abs ((f2 . y1) - (f2 . y2)) < r / (2 * (max ((abs x1) + 1),((abs x2) + 1)))
by A23, A26;
A30:
abs (f1 . y1) < max ((abs x1) + 1),
((abs x2) + 1)
by A13, A24;
A31:
0 <= abs ((f2 . y1) - (f2 . y2))
by COMPLEX1:132;
0 <= abs (f1 . y1)
by COMPLEX1:132;
then A32:
abs ((f1 . y1) * ((f2 . y1) - (f2 . y2))) < (max ((abs x1) + 1),((abs x2) + 1)) * (r / (2 * (max ((abs x1) + 1),((abs x2) + 1))))
by A28, A29, A30, A31, XREAL_1:98;
A33:
abs (((f1 . y1) - (f1 . y2)) * (f2 . y2)) = (abs (f2 . y2)) * (abs ((f1 . y1) - (f1 . y2)))
by COMPLEX1:151;
(
y1 in dom (f1 | X) &
y2 in dom (f1 | X) )
by A25, Z1, RELAT_1:91;
then A34:
abs ((f1 . y1) - (f1 . y2)) < r / (2 * (max ((abs x1) + 1),((abs x2) + 1)))
by A22, A26;
A35:
abs (f2 . y2) < max ((abs x1) + 1),
((abs x2) + 1)
by A13, A24;
A36:
0 <= abs ((f1 . y1) - (f1 . y2))
by COMPLEX1:132;
0 <= abs (f2 . y2)
by COMPLEX1:132;
then
abs (((f1 . y1) - (f1 . y2)) * (f2 . y2)) < (max ((abs x1) + 1),((abs x2) + 1)) * (r / (2 * (max ((abs x1) + 1),((abs x2) + 1))))
by A33, A34, A35, A36, XREAL_1:98;
then A37:
(abs ((f1 . y1) * ((f2 . y1) - (f2 . y2)))) + (abs (((f1 . y1) - (f1 . y2)) * (f2 . y2))) < ((max ((abs x1) + 1),((abs x2) + 1)) * (r / (2 * (max ((abs x1) + 1),((abs x2) + 1))))) + ((max ((abs x1) + 1),((abs x2) + 1)) * (r / (2 * (max ((abs x1) + 1),((abs x2) + 1)))))
by A32, XREAL_1:10;
((max ((abs x1) + 1),((abs x2) + 1)) * (r / (2 * (max ((abs x1) + 1),((abs x2) + 1))))) + ((max ((abs x1) + 1),((abs x2) + 1)) * (r / (2 * (max ((abs x1) + 1),((abs x2) + 1))))) =
(max ((abs x1) + 1),((abs x2) + 1)) * ((r / ((max ((abs x1) + 1),((abs x2) + 1)) * 2)) + (r / ((max ((abs x1) + 1),((abs x2) + 1)) * 2)))
.=
(r / (max ((abs x1) + 1),((abs x2) + 1))) * (max ((abs x1) + 1),((abs x2) + 1))
by XCMPLX_1:119
.=
r
by A19, XCMPLX_1:88
;
hence
abs (((f1 (#) f2) . y1) - ((f1 (#) f2) . y2)) < r
by A27, A37, XXREAL_0:2;
:: thesis: verum
end;
hence
(f1 (#) f2) | (((X /\ Z) /\ X1) /\ Z1) is uniformly_continuous
by Def1; :: thesis: verum