let x1, x2 be object ; for D, D9 being non empty set
for p being FinSequence of D
for f being Function of D,D9 st p = <*x1,x2*> holds
f * p = <*(f . x1),(f . x2)*>
let D, D9 be non empty set ; for p being FinSequence of D
for f being Function of D,D9 st p = <*x1,x2*> holds
f * p = <*(f . x1),(f . x2)*>
let p be FinSequence of D; for f being Function of D,D9 st p = <*x1,x2*> holds
f * p = <*(f . x1),(f . x2)*>
let f be Function of D,D9; ( p = <*x1,x2*> implies f * p = <*(f . x1),(f . x2)*> )
assume A1:
p = <*x1,x2*>
; f * p = <*(f . x1),(f . x2)*>
A2:
p . 2 = x2
by A1;
reconsider q = f * p as FinSequence of D9 by Th30;
len p = 2
by A1, FINSEQ_1:44;
then A3:
len q = 2
by Th31;
then
2 in Seg (len q)
;
then
2 in dom q
by FINSEQ_1:def 3;
then A4:
q . 2 = f . x2
by A2, FUNCT_1:12;
1 in Seg (len q)
by A3;
then A5:
1 in dom q
by FINSEQ_1:def 3;
p . 1 = x1
by A1;
then
q . 1 = f . x1
by A5, FUNCT_1:12;
hence
f * p = <*(f . x1),(f . x2)*>
by A3, A4, FINSEQ_1:44; verum