Metamath Proof Explorer


Theorem knoppcld

Description: Closure theorem for Knopp's function. (Contributed by Asger C. Ipsen, 26-Jul-2021)

Ref Expression
Hypotheses knoppcld.t
|- T = ( x e. RR |-> ( abs ` ( ( |_ ` ( x + ( 1 / 2 ) ) ) - x ) ) )
knoppcld.f
|- F = ( y e. RR |-> ( n e. NN0 |-> ( ( C ^ n ) x. ( T ` ( ( ( 2 x. N ) ^ n ) x. y ) ) ) ) )
knoppcld.w
|- W = ( w e. RR |-> sum_ i e. NN0 ( ( F ` w ) ` i ) )
knoppcld.a
|- ( ph -> A e. RR )
knoppcld.n
|- ( ph -> N e. NN )
knoppcld.1
|- ( ph -> C e. RR )
knoppcld.2
|- ( ph -> ( abs ` C ) < 1 )
Assertion knoppcld
|- ( ph -> ( W ` A ) e. CC )

Proof

Step Hyp Ref Expression
1 knoppcld.t
 |-  T = ( x e. RR |-> ( abs ` ( ( |_ ` ( x + ( 1 / 2 ) ) ) - x ) ) )
2 knoppcld.f
 |-  F = ( y e. RR |-> ( n e. NN0 |-> ( ( C ^ n ) x. ( T ` ( ( ( 2 x. N ) ^ n ) x. y ) ) ) ) )
3 knoppcld.w
 |-  W = ( w e. RR |-> sum_ i e. NN0 ( ( F ` w ) ` i ) )
4 knoppcld.a
 |-  ( ph -> A e. RR )
5 knoppcld.n
 |-  ( ph -> N e. NN )
6 knoppcld.1
 |-  ( ph -> C e. RR )
7 knoppcld.2
 |-  ( ph -> ( abs ` C ) < 1 )
8 1 2 3 5 6 7 knoppcn
 |-  ( ph -> W e. ( RR -cn-> CC ) )
9 cncff
 |-  ( W e. ( RR -cn-> CC ) -> W : RR --> CC )
10 8 9 syl
 |-  ( ph -> W : RR --> CC )
11 10 4 ffvelrnd
 |-  ( ph -> ( W ` A ) e. CC )