Theorem elexi

Description: If a class is a member of another class, then it is a set. Inference associated with elex . (Contributed by NM, 11-Jun-1994)

	Ref	Expression
Hypothesis	elexi.1	|- A e. B
Assertion	elexi	|- A e. _V

Proof

Step	Hyp	Ref	Expression
1		elexi.1	|- A e. B
2		elex	|- ( A e. B -> A e. _V )
3	1 2	ax-mp	|- A e. _V