let T be non empty TopSpace; :: thesis: ( T is normal implies for A being closed Subset of T
for f being Function of (T | A),(Closed-Interval-TSpace (- 1),1) st f is continuous holds
ex g being continuous Function of T,(Closed-Interval-TSpace (- 1),1) st g | A = f )
assume A1:
T is normal
; :: thesis: for A being closed Subset of T
for f being Function of (T | A),(Closed-Interval-TSpace (- 1),1) st f is continuous holds
ex g being continuous Function of T,(Closed-Interval-TSpace (- 1),1) st g | A = f
let A be closed Subset of T; :: thesis: for f being Function of (T | A),(Closed-Interval-TSpace (- 1),1) st f is continuous holds
ex g being continuous Function of T,(Closed-Interval-TSpace (- 1),1) st g | A = f
let f be Function of (T | A),(Closed-Interval-TSpace (- 1),1); :: thesis: ( f is continuous implies ex g being continuous Function of T,(Closed-Interval-TSpace (- 1),1) st g | A = f )
assume A2:
f is continuous
; :: thesis: ex g being continuous Function of T,(Closed-Interval-TSpace (- 1),1) st g | A = f
A3:
the carrier of (Closed-Interval-TSpace (- 1),1) = [.(- 1),1.]
by TOPMETR:25;
A4:
the carrier of (T | A) = A
by PRE_TOPC:29;
per cases
( A is empty or not A is empty )
;
suppose
not
A is
empty
;
:: thesis: ex g being continuous Function of T,(Closed-Interval-TSpace (- 1),1) st g | A = fthen reconsider A1 =
A as non
empty Subset of
T ;
set DF =
Funcs the
carrier of
T,the
carrier of
R^1 ;
set D =
{ q where q is Element of Funcs the carrier of T,the carrier of R^1 : q is continuous Function of T,R^1 } ;
T --> (R^1 0 ) is
Element of
Funcs the
carrier of
T,the
carrier of
R^1
by FUNCT_2:11;
then
T --> (R^1 0 ) in { q where q is Element of Funcs the carrier of T,the carrier of R^1 : q is continuous Function of T,R^1 }
;
then reconsider D =
{ q where q is Element of Funcs the carrier of T,the carrier of R^1 : q is continuous Function of T,R^1 } as non
empty set ;
reconsider f1 =
f as
Function of
(T | A1),
R^1 by TOPREALA:28;
f1 is
continuous
by A2, PRE_TOPC:56;
then reconsider f1 =
f as
continuous Function of
(T | A1),
R^1 ;
f1,
A is_absolutely_bounded_by 1
then consider g0 being
continuous Function of
T,
R^1 such that A8:
g0,
dom g0 is_absolutely_bounded_by 1
/ 3
and A9:
f1 - g0,
A is_absolutely_bounded_by (2 * 1) / 3
by A1, Th19;
g0 in Funcs the
carrier of
T,the
carrier of
R^1
by FUNCT_2:11;
then
g0 in D
;
then reconsider g0d =
g0 as
Element of
D ;
defpred S1[
Element of
NAT ,
set ,
set ]
means ex
E2 being
continuous Function of
T,
R^1 st
(
E2 = $2 & (
f - E2,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ $1) implies ex
g being
continuous Function of
T,
R^1 st
( $3
= E2 + g &
g,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ ($1 + 1)) &
(f - E2) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ ($1 + 1)) ) ) );
A10:
for
n being
Element of
NAT for
x being
Element of
D ex
y being
Element of
D st
S1[
n,
x,
y]
proof
let n be
Element of
NAT ;
:: thesis: for x being Element of D ex y being Element of D st S1[n,x,y]let x be
Element of
D;
:: thesis: ex y being Element of D st S1[n,x,y]
x in D
;
then consider E2 being
Element of
Funcs the
carrier of
T,the
carrier of
R^1 such that A11:
(
E2 = x &
E2 is
continuous Function of
T,
R^1 )
;
reconsider E2 =
E2 as
continuous Function of
T,
R^1 by A11;
per cases
( not f - E2,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n) or f - E2,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n) )
;
suppose A12:
not
f - E2,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n)
;
:: thesis: ex y being Element of D st S1[n,x,y]take
x
;
:: thesis: S1[n,x,x]take
E2
;
:: thesis: ( E2 = x & ( f - E2,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n) implies ex g being continuous Function of T,R^1 st
( x = E2 + g & g,the carrier of T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) & (f - E2) - g,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) ) ) )thus
(
E2 = x & (
f - E2,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n) implies ex
g being
continuous Function of
T,
R^1 st
(
x = E2 + g &
g,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) &
(f - E2) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) ) ) )
by A11, A12;
:: thesis: verum end; suppose A13:
f - E2,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n)
;
:: thesis: ex y being Element of D st S1[n,x,y]reconsider E2a =
E2 as
RealMap of
T by TOPMETR:24;
reconsider E2a =
E2a as
continuous RealMap of
T by TOPREAL6:83;
reconsider E2b =
E2 | A as
Function of
(T | A1),
R^1 by PRE_TOPC:30;
reconsider E2b =
E2b as
continuous Function of
(T | A1),
R^1 by TOPMETR:10;
E2b c= E2
by RELAT_1:88;
then A14:
f - E2b,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n)
by A13, Th4, Th17;
set k =
f1 - E2b;
reconsider k =
f1 - E2b as
Function of
(T | A1),
R^1 by TOPMETR:24;
reconsider f1c =
f1,
E2c =
E2b as
RealMap of
(T | A1) by TOPMETR:24;
reconsider f1c =
f1c,
E2c =
E2c as
continuous RealMap of
(T | A1) by TOPREAL6:83;
f1c - E2c is
continuous
;
then A15:
k is
continuous
by TOPREAL6:83;
set r =
(2 / 3) * ((2 / 3) |^ n);
(2 / 3) |^ n > 0
by NEWTON:102;
then
(2 / 3) * ((2 / 3) |^ n) > 0
by XREAL_1:131;
then consider g being
continuous Function of
T,
R^1 such that A16:
g,
dom g is_absolutely_bounded_by ((2 / 3) * ((2 / 3) |^ n)) / 3
and A17:
k - g,
A is_absolutely_bounded_by (2 * ((2 / 3) * ((2 / 3) |^ n))) / 3
by A1, A14, A15, Th19;
reconsider ga =
g as
RealMap of
T by TOPMETR:24;
reconsider ga =
ga as
continuous RealMap of
T by TOPREAL6:83;
set y =
E2a + ga;
reconsider y1 =
E2a + ga as
Function of
T,
R^1 by TOPMETR:24;
A18:
y1 in Funcs the
carrier of
T,the
carrier of
R^1
by FUNCT_2:11;
y1 is
continuous Function of
T,
R^1
by TOPREAL6:83;
then
E2a + ga in D
by A18;
then reconsider y =
E2a + ga as
Element of
D ;
take
y
;
:: thesis: S1[n,x,y]take
E2
;
:: thesis: ( E2 = x & ( f - E2,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n) implies ex g being continuous Function of T,R^1 st
( y = E2 + g & g,the carrier of T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) & (f - E2) - g,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) ) ) )thus
E2 = x
by A11;
:: thesis: ( f - E2,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n) implies ex g being continuous Function of T,R^1 st
( y = E2 + g & g,the carrier of T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) & (f - E2) - g,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) ) )assume
f - E2,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n)
;
:: thesis: ex g being continuous Function of T,R^1 st
( y = E2 + g & g,the carrier of T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) & (f - E2) - g,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) )take
g
;
:: thesis: ( y = E2 + g & g,the carrier of T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) & (f - E2) - g,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) )thus
y = E2 + g
;
:: thesis: ( g,the carrier of T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) & (f - E2) - g,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) )A19:
(2 / 3) * ((2 / 3) |^ n) = (2 / 3) |^ (n + 1)
by NEWTON:11;
hence
g,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1))
by A16, FUNCT_2:def 1;
:: thesis: (f - E2) - g,A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1))A20:
dom f = the
carrier of
(T | A)
by FUNCT_2:def 1;
A21:
dom E2b = the
carrier of
(T | A)
by FUNCT_2:def 1;
A22:
dom g = the
carrier of
T
by FUNCT_2:def 1;
A23:
dom ((f - E2b) - g) =
(dom (f - E2b)) /\ (dom g)
by VALUED_1:12
.=
((dom f) /\ (dom E2b)) /\ (dom g)
by VALUED_1:12
.=
A
by A4, A20, A21, A22, XBOOLE_1:28
;
((f - E2b) - g) | A =
((f - E2b) | A) - g
by RFUNCT_1:63
.=
(f - (E2b | A)) - g
by RFUNCT_1:63
.=
(f - (E2 | A)) - g
by RELAT_1:101
.=
((f - E2) | A) - g
by RFUNCT_1:63
.=
((f - E2) - g) | A
by RFUNCT_1:63
;
hence
(f - E2) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1))
by A17, A19, A23, Th18;
:: thesis: verum end; end;
end; consider F being
Function of
NAT ,
D such that A24:
F . 0 = g0d
and A25:
for
n being
Element of
NAT holds
S1[
n,
F . n,
F . (n + 1)]
from RECDEF_1:sch 2(A10);
A26:
dom F = NAT
by FUNCT_2:def 1;
A27:
( the
carrier of
RealSpace = REAL & the
carrier of
R^1 = REAL )
by METRIC_1:def 14, TOPMETR:16, TOPMETR:def 7;
then reconsider F =
F as
Functional_Sequence of the
carrier of
T,
REAL by A26, SEQFUNC:1;
then A28:
the
carrier of
T common_on_dom F
by SEQFUNC:def 10;
A29:
( 2
/ 9
> 0 & 2
/ 3
> 0 )
;
defpred S2[
Nat]
means (
F . $1 is
continuous Function of
T,
R^1 &
(F . $1) - (F . ($1 + 1)),the
carrier of
T is_absolutely_bounded_by (2 / 9) * ((2 / 3) to_power $1) &
(F . $1) - f,
A1 is_absolutely_bounded_by (2 / 3) * ((2 / 3) to_power $1) );
consider E2 being
continuous Function of
T,
R^1 such that A30:
(
E2 = F . 0 & (
f - E2,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ 0 ) implies ex
g being
continuous Function of
T,
R^1 st
(
F . (0 + 1) = E2 + g &
g,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (0 + 1)) &
(f - E2) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (0 + 1)) ) ) )
by A25;
A31:
(
(2 * 1) / 3
= (2 / 3) * 1 &
(2 / 3) to_power 0 = 1 &
(2 / 3) |^ 0 = 1 )
by NEWTON:9, POWER:29;
then consider g1 being
continuous Function of
T,
R^1 such that A32:
(
F . (0 + 1) = E2 + g1 &
g1,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (0 + 1)) &
(f - E2) - g1,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (0 + 1)) )
by A9, A24, A30;
A33:
(1 / 3) * ((2 / 3) |^ 1) = (1 / 3) * (2 / 3)
by NEWTON:10;
A34:
dom g1 =
the
carrier of
T
by FUNCT_2:def 1
.=
dom E2
by FUNCT_2:def 1
;
A35:
dom ((g1 + E2) - E2) =
(dom (g1 + E2)) /\ (dom E2)
by VALUED_1:12
.=
((dom g1) /\ (dom E2)) /\ (dom E2)
by VALUED_1:def 1
.=
dom g1
by A34
;
then
(
(1 / 3) * ((2 / 3) |^ (0 + 1)) = (2 / 9) * 1 &
(F . (0 + 1)) - (F . 0 ) = g1 )
by A30, A32, A33, A35, FUNCT_1:9;
then A37:
S2[
0 ]
by A9, A24, A31, A32, Th24;
A38:
now let n be
Element of
NAT ;
:: thesis: ( S2[n] implies S2[n + 1] )consider E2 being
continuous Function of
T,
R^1 such that A39:
(
E2 = F . n & (
f - E2,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n) implies ex
g being
continuous Function of
T,
R^1 st
(
F . (n + 1) = E2 + g &
g,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) &
(f - E2) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) ) ) )
by A25;
assume
S2[
n]
;
:: thesis: S2[n + 1]then
(F . n) - f,
A1 is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ n)
by POWER:46;
then consider g being
continuous Function of
T,
R^1 such that A40:
(
F . (n + 1) = E2 + g &
g,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ (n + 1)) &
(f - E2) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) )
by A39, Th24;
reconsider E2' =
E2 as
continuous RealMap of
T by A27, TOPREAL6:83;
reconsider g' =
g as
continuous RealMap of
T by A27, TOPREAL6:83;
A41:
E2' + g' is
continuous RealMap of
T
;
consider E3 being
continuous Function of
T,
R^1 such that A42:
(
E3 = F . (n + 1) & (
f - E3,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ (n + 1)) implies ex
g being
continuous Function of
T,
R^1 st
(
F . ((n + 1) + 1) = E3 + g &
g,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ ((n + 1) + 1)) &
(f - E3) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ ((n + 1) + 1)) ) ) )
by A25;
A43:
(f - E2) - g,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) to_power (n + 1))
by A40, POWER:46;
A44:
dom f =
[#] (T | A1)
by FUNCT_2:def 1
.=
A
by PRE_TOPC:def 10
;
A45:
dom ((f - E2) - g) =
(dom (f - E2)) /\ (dom g)
by VALUED_1:12
.=
((dom f) /\ (dom E2)) /\ (dom g)
by VALUED_1:12
.=
((dom f) /\ the carrier of T) /\ (dom g)
by FUNCT_2:def 1
.=
(dom f) /\ (dom g)
by A44, XBOOLE_1:28
.=
(dom f) /\ the
carrier of
T
by FUNCT_2:def 1
.=
A
by A44, XBOOLE_1:28
;
A46:
dom (f - (E2 + g)) =
(dom f) /\ (dom (E2 + g))
by VALUED_1:12
.=
A /\ ((dom E2) /\ (dom g))
by A44, VALUED_1:def 1
.=
A /\ ((dom E2) /\ the carrier of T)
by FUNCT_2:def 1
.=
A /\ (the carrier of T /\ the carrier of T)
by FUNCT_2:def 1
.=
A
by XBOOLE_1:28
;
A47:
dom (f - E2) =
A /\ (dom E2)
by A44, VALUED_1:12
.=
A /\ the
carrier of
T
by FUNCT_2:def 1
.=
A
by XBOOLE_1:28
;
then A50:
f - (F . (n + 1)),
A1 is_absolutely_bounded_by (2 / 3) * ((2 / 3) to_power (n + 1))
by A40, A43, A45, A46, FUNCT_1:9;
consider gx being
continuous Function of
T,
R^1 such that A51:
(
F . ((n + 1) + 1) = E3 + gx &
gx,the
carrier of
T is_absolutely_bounded_by (1 / 3) * ((2 / 3) |^ ((n + 1) + 1)) &
(f - E3) - gx,
A is_absolutely_bounded_by (2 / 3) * ((2 / 3) |^ ((n + 1) + 1)) )
by A40, A42, A45, A46, A48, FUNCT_1:9;
A52:
(2 / 9) * ((2 / 3) to_power (n + 1)) =
((1 / 3) * (2 / 3)) * ((2 / 3) |^ (n + 1))
by POWER:46
.=
(1 / 3) * ((2 / 3) * ((2 / 3) |^ (n + 1)))
.=
(1 / 3) * ((2 / 3) |^ ((n + 1) + 1))
by NEWTON:11
;
A53:
dom gx =
the
carrier of
T
by FUNCT_2:def 1
.=
dom E3
by FUNCT_2:def 1
;
A54:
dom ((gx + E3) - E3) =
(dom (gx + E3)) /\ (dom E3)
by VALUED_1:12
.=
((dom gx) /\ (dom E3)) /\ (dom E3)
by VALUED_1:def 1
.=
dom gx
by A53
;
then
(F . ((n + 1) + 1)) - (F . (n + 1)) = gx
by A42, A51, A54, FUNCT_1:9;
hence
S2[
n + 1]
by A27, A40, A41, A50, A51, A52, Th24, TOPREAL6:83;
:: thesis: verum end; A56:
for
n being
Element of
NAT holds
S2[
n]
from NAT_1:sch 1(A37, A38);
then A58:
F is_unif_conv_on the
carrier of
T
by A28, A29, Th11;
then reconsider h =
lim F,the
carrier of
T as
continuous Function of
T,
R^1 by A56, Th22;
A60:
A1 common_on_dom F
by A28, SEQFUNC:24;
(
dom f = the
carrier of
(T | A1) &
rng f c= REAL )
by FUNCT_2:def 1, VALUED_0:def 3;
then A61:
f is
Function of
A1,
REAL
by A4, FUNCT_2:4;
F is_point_conv_on the
carrier of
T
by A58, SEQFUNC:23;
then A62:
h | A1 =
lim F,
A1
by SEQFUNC:25
.=
f
by A29, A59, A60, A61, Th13
;
h,the
carrier of
T is_absolutely_bounded_by 1
then reconsider h =
h as
Function of
T,
(Closed-Interval-TSpace (- 1),1) by Th23;
R^1 [.(- 1),1.] = [#] (Closed-Interval-TSpace (- 1),1)
by A3, TOPREALB:def 3;
then
Closed-Interval-TSpace (- 1),1
= R^1 | (R^1 [.(- 1),1.])
by PRE_TOPC:def 10;
then
h is
continuous
by TOPMETR:9;
hence
ex
g being
continuous Function of
T,
(Closed-Interval-TSpace (- 1),1) st
g | A = f
by A62;
:: thesis: verum end; end;