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	$$⊢A\in F\left(B\right)\to B\in \mathrm{V}$$

Proof

Step	Hyp	Ref	Expression
1		elfvdm	$$⊢A\in F\left(B\right)\to B\in \mathrm{dom}F$$
2	1	elexd	$$⊢A\in F\left(B\right)\to B\in \mathrm{V}$$