let a be set ; for p being FinSequence
for F being Function st [:{a},(rng p):] c= dom F holds
F [;] a,p is FinSequence
let p be FinSequence; for F being Function st [:{a},(rng p):] c= dom F holds
F [;] a,p is FinSequence
let F be Function; ( [:{a},(rng p):] c= dom F implies F [;] a,p is FinSequence )
assume
[:{a},(rng p):] c= dom F
; F [;] a,p is FinSequence
then
dom (F [;] a,p) = dom p
by Lm4;
then
dom (F [;] a,p) = Seg (len p)
by FINSEQ_1:def 3;
hence
F [;] a,p is FinSequence
by FINSEQ_1:def 2; verum