Theorem bnj1317

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

	Ref	Expression
Hypothesis	bnj1317.1	|- A = { x | ph }
Assertion	bnj1317	|- ( y e. A -> A. x y e. A )

Proof

Step	Hyp	Ref	Expression
1		bnj1317.1	|- A = { x | ph }
2		hbab1	|- ( y e. { x | ph } -> A. x y e. { x | ph } )
3	1 2	hbxfreq	|- ( y e. A -> A. x y e. A )