Theorem elfvex

Description: If a function value has a member, then the argument is a set. (An artifact of our function value definition.) (Contributed by Mario Carneiro, 6-Nov-2015)

	Ref	Expression
Assertion	elfvex	|- ( A e. ( F ` B ) -> B e. _V )

Proof

Step	Hyp	Ref	Expression
1		elfvdm	|- ( A e. ( F ` B ) -> B e. dom F )
2	1	elexd	|- ( A e. ( F ` B ) -> B e. _V )