set f = seq_n^ 8;
let e be Real; ( 0 < e & e < 1 implies ex s being eventually-positive Real_Sequence st
( s = seq_a^ (1 + e),1,0 & Big_Oh (seq_n^ 8) c= Big_Oh s & not Big_Oh (seq_n^ 8) = Big_Oh s ) )
assume that
A1:
0 < e
and
A2:
e < 1
; ex s being eventually-positive Real_Sequence st
( s = seq_a^ (1 + e),1,0 & Big_Oh (seq_n^ 8) c= Big_Oh s & not Big_Oh (seq_n^ 8) = Big_Oh s )
consider N being Element of NAT such that
A3:
for n being Element of NAT st n >= N holds
(n * (log 2,(1 + e))) - (8 * (log 2,n)) > 8 * (log 2,n)
by A1, A2, Lm25;
set g = seq_a^ (1 + e),1,0 ;
set h = (seq_n^ 8) /" (seq_a^ (1 + e),1,0 );
reconsider g = seq_a^ (1 + e),1,0 as eventually-positive Real_Sequence by A1;
take
g
; ( g = seq_a^ (1 + e),1,0 & Big_Oh (seq_n^ 8) c= Big_Oh g & not Big_Oh (seq_n^ 8) = Big_Oh g )
thus
g = seq_a^ (1 + e),1,0
; ( Big_Oh (seq_n^ 8) c= Big_Oh g & not Big_Oh (seq_n^ 8) = Big_Oh g )
A4:
now let p be
real number ;
( p > 0 implies ex N1 being Element of NAT st
for n being Element of NAT st n >= N1 holds
abs ((((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n) - 0 ) < p )assume A5:
p > 0
;
ex N1 being Element of NAT st
for n being Element of NAT st n >= N1 holds
abs ((((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n) - 0 ) < preconsider p1 =
p as
Real by XREAL_0:def 1;
A6:
(1 / p1) to_power (1 / 8) > 0
by A5, POWER:39;
set N1 =
max N,
(max [/((1 / p1) to_power (1 / 8))\],2);
A7:
max N,
(max [/((1 / p1) to_power (1 / 8))\],2) >= N
by XXREAL_0:25;
A8:
max N,
(max [/((1 / p1) to_power (1 / 8))\],2) is
Integer
A9:
max N,
(max [/((1 / p1) to_power (1 / 8))\],2) >= max [/((1 / p) to_power (1 / 8))\],2
by XXREAL_0:25;
max [/((1 / p) to_power (1 / 8))\],2
>= [/((1 / p) to_power (1 / 8))\]
by XXREAL_0:25;
then A10:
max N,
(max [/((1 / p1) to_power (1 / 8))\],2) >= [/((1 / p) to_power (1 / 8))\]
by A9, XXREAL_0:2;
reconsider N1 =
max N,
(max [/((1 / p1) to_power (1 / 8))\],2) as
Element of
NAT by A7, A8, INT_1:16;
take N1 =
N1;
for n being Element of NAT st n >= N1 holds
abs ((((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n) - 0 ) < plet n be
Element of
NAT ;
( n >= N1 implies abs ((((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n) - 0 ) < p )assume A11:
n >= N1
;
abs ((((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n) - 0 ) < pthen
n >= N
by A7, XXREAL_0:2;
then
(n * (log 2,(1 + e))) - (8 * (log 2,n)) > 8
* (log 2,n)
by A3;
then A12:
2
to_power ((n * (log 2,(1 + e))) - (8 * (log 2,n))) > 2
to_power (8 * (log 2,n))
by POWER:44;
A13:
max [/((1 / p) to_power (1 / 8))\],2
>= 2
by XXREAL_0:25;
A14:
g . n = (1 + e) to_power ((1 * n) + 0 )
by Def1;
((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n = ((seq_n^ 8) . n) / (g . n)
by Lm4;
then A15:
((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n =
(n to_power 8) / ((1 + e) to_power n)
by A9, A13, A11, A14, Def3
.=
(2 to_power (8 * (log 2,n))) / ((1 + e) to_power n)
by A9, A13, A11, Lm3
.=
(2 to_power (8 * (log 2,n))) / (2 to_power (n * (log 2,(1 + e))))
by A1, Lm3
.=
2
to_power ((8 * (log 2,n)) - (n * (log 2,(1 + e))))
by POWER:34
.=
2
to_power (- ((n * (log 2,(1 + e))) - (8 * (log 2,n))))
;
[/((1 / p) to_power (1 / 8))\] >= (1 / p) to_power (1 / 8)
by INT_1:def 5;
then
N1 >= (1 / p) to_power (1 / 8)
by A10, XXREAL_0:2;
then
n >= (1 / p) to_power (1 / 8)
by A11, XXREAL_0:2;
then
n to_power 8
>= ((1 / p) to_power (1 / 8)) to_power 8
by A6, Lm6;
then
n to_power 8
>= (1 / p1) to_power ((1 / 8) * 8)
by A5, POWER:38;
then
n to_power 8
>= 1
/ p1
by POWER:30;
then
1
/ (n to_power 8) <= 1
/ (p " )
by A5, XREAL_1:87;
then
1
/ (2 to_power (8 * (log 2,n))) <= p
by A9, A13, A11, Lm3;
then A16:
2
to_power (- (8 * (log 2,n))) <= p
by POWER:33;
2
to_power (8 * (log 2,n)) > 0
by POWER:39;
then
1
/ (2 to_power ((n * (log 2,(1 + e))) - (8 * (log 2,n)))) < 1
/ (2 to_power (8 * (log 2,n)))
by A12, XREAL_1:90;
then
2
to_power (- ((n * (log 2,(1 + e))) - (8 * (log 2,n)))) < 1
/ (2 to_power (8 * (log 2,n)))
by POWER:33;
then
((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n < 2
to_power (- (8 * (log 2,n)))
by A15, POWER:33;
then A17:
((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n < p
by A16, XXREAL_0:2;
((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n > 0
by A15, POWER:39;
hence
abs ((((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) . n) - 0 ) < p
by A17, ABSVALUE:def 1;
verum end;
then A18:
(seq_n^ 8) /" (seq_a^ (1 + e),1,0 ) is convergent
by SEQ_2:def 6;
then A19:
lim ((seq_n^ 8) /" (seq_a^ (1 + e),1,0 )) = 0
by A4, SEQ_2:def 7;
then
not g in Big_Oh (seq_n^ 8)
by A18, ASYMPT_0:16;
then A20:
not seq_n^ 8 in Big_Omega g
by ASYMPT_0:19;
seq_n^ 8 in Big_Oh g
by A18, A19, ASYMPT_0:16;
hence
( Big_Oh (seq_n^ 8) c= Big_Oh g & not Big_Oh (seq_n^ 8) = Big_Oh g )
by A20, Th4; verum