let p be Rational; for s1, s2 being Real_Sequence st s1 is convergent & s2 is convergent & lim s1 > 0 & p >= 0 & ( for n being Element of NAT holds
( s1 . n > 0 & s2 . n = (s1 . n) #Q p ) ) holds
lim s2 = (lim s1) #Q p
let s1, s2 be Real_Sequence; ( s1 is convergent & s2 is convergent & lim s1 > 0 & p >= 0 & ( for n being Element of NAT holds
( s1 . n > 0 & s2 . n = (s1 . n) #Q p ) ) implies lim s2 = (lim s1) #Q p )
assume that
A1:
s1 is convergent
and
A2:
s2 is convergent
and
A3:
lim s1 > 0
and
A4:
p >= 0
and
A5:
for n being Element of NAT holds
( s1 . n > 0 & s2 . n = (s1 . n) #Q p )
; lim s2 = (lim s1) #Q p
reconsider s = NAT --> (lim s1) as Real_Sequence ;
consider m0 being Element of NAT such that
A6:
p < m0
by SEQ_4:3;
A7: lim s =
s . 0
by SEQ_4:26
.=
lim s1
by FUNCOP_1:7
;
then A8:
s1 /" s is convergent
by A1, A3, SEQ_2:23;
deffunc H1( Element of NAT ) -> Element of REAL = ((s /" s1) . $1) |^ m0;
consider s3 being Real_Sequence such that
A9:
for n being Element of NAT holds s3 . n = H1(n)
from SEQ_1:sch 1();
for n being Element of NAT holds s1 . n <> 0
by A5;
then A10:
s1 is non-empty
by SEQ_1:5;
then A11:
s /" s1 is convergent
by A1, A3, SEQ_2:23;
then A12:
s3 is convergent
by A9, Th26;
reconsider q = m0 as Rational ;
deffunc H2( Element of NAT ) -> Element of REAL = ((s1 /" s) . $1) |^ m0;
consider s4 being Real_Sequence such that
A13:
for n being Element of NAT holds s4 . n = H2(n)
from SEQ_1:sch 1();
lim (s /" s1) =
(lim s) / (lim s1)
by A1, A3, A10, SEQ_2:24
.=
1
by A3, A7, XCMPLX_1:60
;
then
lim s3 = 1 |^ m0
by A11, A9, Th26;
then A14:
lim s3 = 1
by NEWTON:10;
lim (s1 /" s) =
(lim s1) / (lim s)
by A1, A3, A7, SEQ_2:24
.=
1
by A3, A7, XCMPLX_1:60
;
then
lim s4 = 1 |^ m0
by A8, A13, Th26;
then A15:
lim s4 = 1
by NEWTON:10;
s2 is bounded
by A2, SEQ_2:13;
then consider d being real number such that
A16:
d > 0
and
A17:
for n being Element of NAT holds abs (s2 . n) < d
by SEQ_2:3;
A18:
s4 is convergent
by A8, A13, Th26;
now let c be
real number ;
( c > 0 implies ex n being Element of NAT st
for m being Element of NAT st m >= n holds
abs ((s2 . m) - ((lim s1) #Q p)) < c )assume A19:
c > 0
;
ex n being Element of NAT st
for m being Element of NAT st m >= n holds
abs ((s2 . m) - ((lim s1) #Q p)) < cthen
c / d > 0
by A16, XREAL_1:139;
then consider m1 being
Element of
NAT such that A20:
for
m being
Element of
NAT st
m >= m1 holds
abs ((s3 . m) - 1) < c / d
by A12, A14, SEQ_2:def 7;
A21:
(lim s1) #Q p > 0
by A3, Th63;
then A22:
abs ((lim s1) #Q p) > 0
by ABSVALUE:def 1;
then
c / (abs ((lim s1) #Q p)) > 0
by A19, XREAL_1:139;
then consider m2 being
Element of
NAT such that A23:
for
m being
Element of
NAT st
m >= m2 holds
abs ((s4 . m) - 1) < c / (abs ((lim s1) #Q p))
by A18, A15, SEQ_2:def 7;
take n =
m1 + m2;
for m being Element of NAT st m >= n holds
abs ((s2 . m) - ((lim s1) #Q p)) < clet m be
Element of
NAT ;
( m >= n implies abs ((s2 . m) - ((lim s1) #Q p)) < c )assume A24:
m >= n
;
abs ((s2 . m) - ((lim s1) #Q p)) < c
m2 <= n
by NAT_1:11;
then A25:
m >= m2
by A24, XXREAL_0:2;
m1 <= n
by NAT_1:11;
then A26:
m >= m1
by A24, XXREAL_0:2;
now per cases
( s1 . m >= lim s1 or s1 . m <= lim s1 )
;
suppose A27:
s1 . m >= lim s1
;
abs ((s2 . m) - ((lim s1) #Q p)) < cA28:
(s1 . m) / (lim s1) =
(s1 . m) / (s . m)
by FUNCOP_1:7
.=
(s1 . m) * ((s . m) ")
.=
(s1 . m) * ((s ") . m)
by VALUED_1:10
.=
(s1 /" s) . m
by SEQ_1:8
;
(s1 . m) * ((lim s1) ") >= (lim s1) * ((lim s1) ")
by A3, A27, XREAL_1:64;
then A29:
(s1 /" s) . m >= 1
by A3, A28, XCMPLX_0:def 7;
then
((s1 /" s) . m) #Q p <= ((s1 /" s) . m) #Q q
by A6, Th74;
then
((s1 /" s) . m) #Q p <= ((s1 /" s) . m) |^ m0
by A29, Th60;
then A30:
(((s1 /" s) . m) #Q p) - 1
<= (((s1 /" s) . m) |^ m0) - 1
by XREAL_1:9;
((s1 /" s) . m) #Q p >= 1
by A4, A29, Th71;
then
(((s1 /" s) . m) #Q p) - 1
>= 1
- 1
by XREAL_1:9;
then A31:
(((s1 /" s) . m) #Q p) - 1
= abs ((((s1 /" s) . m) #Q p) - 1)
by ABSVALUE:def 1;
A32:
(lim s1) #Q p <> 0
by A3, Th63;
A33:
abs ((s4 . m) - 1) < c / (abs ((lim s1) #Q p))
by A23, A25;
A34:
s1 . m > 0
by A5;
((s1 /" s) . m) |^ m0 >= 1
by A29, Th19;
then
(((s1 /" s) . m) |^ m0) - 1
>= 1
- 1
by XREAL_1:9;
then
abs ((((s1 /" s) . m) #Q p) - 1) <= abs ((((s1 /" s) . m) |^ m0) - 1)
by A30, A31, ABSVALUE:def 1;
then
abs ((((s1 /" s) . m) #Q p) - 1) <= abs ((s4 . m) - 1)
by A13;
then A35:
abs ((((s1 /" s) . m) #Q p) - 1) < c / (abs ((lim s1) #Q p))
by A33, XXREAL_0:2;
A36:
abs ((lim s1) #Q p) <> 0
by A21, ABSVALUE:def 1;
abs ((s2 . m) - ((lim s1) #Q p)) =
abs ((((s1 . m) #Q p) - ((lim s1) #Q p)) * 1)
by A5
.=
abs ((((s1 . m) #Q p) - ((lim s1) #Q p)) * (((lim s1) #Q p) / ((lim s1) #Q p)))
by A32, XCMPLX_1:60
.=
abs ((((lim s1) #Q p) * (((s1 . m) #Q p) - ((lim s1) #Q p))) / ((lim s1) #Q p))
.=
abs (((lim s1) #Q p) * ((((s1 . m) #Q p) - ((lim s1) #Q p)) / ((lim s1) #Q p)))
.=
(abs ((lim s1) #Q p)) * (abs ((((s1 . m) #Q p) - ((lim s1) #Q p)) / ((lim s1) #Q p)))
by COMPLEX1:65
.=
(abs ((lim s1) #Q p)) * (abs ((((s1 . m) #Q p) / ((lim s1) #Q p)) - (((lim s1) #Q p) / ((lim s1) #Q p))))
.=
(abs ((lim s1) #Q p)) * (abs ((((s1 . m) #Q p) / ((lim s1) #Q p)) - 1))
by A32, XCMPLX_1:60
.=
(abs ((lim s1) #Q p)) * (abs ((((s1 . m) / (lim s1)) #Q p) - 1))
by A3, A34, Th69
;
then
abs ((s2 . m) - ((lim s1) #Q p)) < (abs ((lim s1) #Q p)) * (c / (abs ((lim s1) #Q p)))
by A22, A28, A35, XREAL_1:68;
hence
abs ((s2 . m) - ((lim s1) #Q p)) < c
by A36, XCMPLX_1:87;
verum end; suppose A37:
s1 . m <= lim s1
;
abs ((s2 . m) - ((lim s1) #Q p)) < cA38:
(lim s1) / (s1 . m) =
(s . m) / (s1 . m)
by FUNCOP_1:7
.=
(s . m) * ((s1 . m) ")
.=
(s . m) * ((s1 ") . m)
by VALUED_1:10
.=
(s /" s1) . m
by SEQ_1:8
;
A39:
s1 . m <> 0
by A5;
A40:
s1 . m > 0
by A5;
then
(s1 . m) * ((s1 . m) ") <= (lim s1) * ((s1 . m) ")
by A37, XREAL_1:64;
then A41:
(s /" s1) . m >= 1
by A39, A38, XCMPLX_0:def 7;
then
((s /" s1) . m) #Q p <= ((s /" s1) . m) #Q q
by A6, Th74;
then
((s /" s1) . m) #Q p <= ((s /" s1) . m) |^ m0
by A41, Th60;
then A42:
(((s /" s1) . m) #Q p) - 1
<= (((s /" s1) . m) |^ m0) - 1
by XREAL_1:9;
(s1 . m) #Q p > 0
by A5, Th63;
then A43:
abs ((s1 . m) #Q p) > 0
by ABSVALUE:def 1;
A44:
abs ((s3 . m) - 1) < c / d
by A20, A26;
((s /" s1) . m) #Q p >= 1
by A4, A41, Th71;
then
(((s /" s1) . m) #Q p) - 1
>= 1
- 1
by XREAL_1:9;
then A45:
(((s /" s1) . m) #Q p) - 1
= abs ((((s /" s1) . m) #Q p) - 1)
by ABSVALUE:def 1;
((s /" s1) . m) |^ m0 >= 1
by A41, Th19;
then
(((s /" s1) . m) |^ m0) - 1
>= 1
- 1
by XREAL_1:9;
then
abs ((((s /" s1) . m) #Q p) - 1) <= abs ((((s /" s1) . m) |^ m0) - 1)
by A42, A45, ABSVALUE:def 1;
then
abs ((((s /" s1) . m) #Q p) - 1) <= abs ((s3 . m) - 1)
by A9;
then A46:
abs ((((s /" s1) . m) #Q p) - 1) < c / d
by A44, XXREAL_0:2;
abs (s2 . m) < d
by A17;
then
abs ((s1 . m) #Q p) < d
by A5;
then
(abs ((s1 . m) #Q p)) / d < d / d
by A16, XREAL_1:74;
then
(abs ((s1 . m) #Q p)) / d < 1
by A16, XCMPLX_1:60;
then A47:
c * ((abs ((s1 . m) #Q p)) / d) < c * 1
by A19, XREAL_1:68;
A48:
(s1 . m) #Q p <> 0
by A5, Th63;
abs ((s2 . m) - ((lim s1) #Q p)) =
abs ((((s1 . m) #Q p) - ((lim s1) #Q p)) * 1)
by A5
.=
abs ((((s1 . m) #Q p) - ((lim s1) #Q p)) * (((s1 . m) #Q p) / ((s1 . m) #Q p)))
by A48, XCMPLX_1:60
.=
abs ((((s1 . m) #Q p) * (((s1 . m) #Q p) - ((lim s1) #Q p))) / ((s1 . m) #Q p))
.=
abs (((s1 . m) #Q p) * ((((s1 . m) #Q p) - ((lim s1) #Q p)) / ((s1 . m) #Q p)))
.=
(abs ((s1 . m) #Q p)) * (abs ((((s1 . m) #Q p) - ((lim s1) #Q p)) / ((s1 . m) #Q p)))
by COMPLEX1:65
.=
(abs ((s1 . m) #Q p)) * (abs ((((s1 . m) #Q p) / ((s1 . m) #Q p)) - (((lim s1) #Q p) / ((s1 . m) #Q p))))
.=
(abs ((s1 . m) #Q p)) * (abs (1 - (((lim s1) #Q p) / ((s1 . m) #Q p))))
by A48, XCMPLX_1:60
.=
(abs ((s1 . m) #Q p)) * (abs (- (1 - (((lim s1) #Q p) / ((s1 . m) #Q p)))))
by COMPLEX1:52
.=
(abs ((s1 . m) #Q p)) * (abs ((((lim s1) #Q p) / ((s1 . m) #Q p)) - 1))
.=
(abs ((s1 . m) #Q p)) * (abs ((((lim s1) / (s1 . m)) #Q p) - 1))
by A3, A40, Th69
;
then
abs ((s2 . m) - ((lim s1) #Q p)) < (abs ((s1 . m) #Q p)) * (c / d)
by A43, A38, A46, XREAL_1:68;
hence
abs ((s2 . m) - ((lim s1) #Q p)) < c
by A47, XXREAL_0:2;
verum end; end; end; hence
abs ((s2 . m) - ((lim s1) #Q p)) < c
;
verum end;
hence
lim s2 = (lim s1) #Q p
by A2, SEQ_2:def 7; verum