Metamath Proof Explorer


Theorem elpmi

Description: A partial function is a function. (Contributed by Mario Carneiro, 15-Sep-2015)

Ref Expression
Assertion elpmi FA𝑝𝑚BF:domFAdomFB

Proof

Step Hyp Ref Expression
1 n0i FA𝑝𝑚B¬A𝑝𝑚B=
2 fnpm 𝑝𝑚FnV×V
3 2 fndmi dom𝑝𝑚=V×V
4 3 ndmov ¬AVBVA𝑝𝑚B=
5 1 4 nsyl2 FA𝑝𝑚BAVBV
6 elpm2g AVBVFA𝑝𝑚BF:domFAdomFB
7 5 6 syl FA𝑝𝑚BFA𝑝𝑚BF:domFAdomFB
8 7 ibi FA𝑝𝑚BF:domFAdomFB