Theorem bnj1198

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

	Ref	Expression
Hypotheses	bnj1198.1	|- ( ph -> E. x ps )
	bnj1198.2	|- ( ps' <-> ps )
Assertion	bnj1198	|- ( ph -> E. x ps' )

Proof

Step	Hyp	Ref	Expression
1		bnj1198.1	|- ( ph -> E. x ps )
2		bnj1198.2	|- ( ps' <-> ps )
3	2	exbii	|- ( E. x ps' <-> E. x ps )
4	1 3	sylibr	|- ( ph -> E. x ps' )