Theorem bnj1238

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

	Ref	Expression
Hypothesis	bnj1238.1	|- ( ph <-> E. x e. A ( ps /\ ch ) )
Assertion	bnj1238	|- ( ph -> E. x e. A ps )

Proof

Step	Hyp	Ref	Expression
1		bnj1238.1	|- ( ph <-> E. x e. A ( ps /\ ch ) )
2		bnj1239	|- ( E. x e. A ( ps /\ ch ) -> E. x e. A ps )
3	1 2	sylbi	|- ( ph -> E. x e. A ps )