Theorem cbvreuvwOLD

Description: Obsolete version of cbvreuvw as of 30-Sep-2024. (Contributed by NM, 5-Apr-2004) (Revised by Gino Giotto, 10-Jan-2024) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	cbvralvw.1	|- ( x = y -> ( ph <-> ps ) )
Assertion	cbvreuvwOLD	|- ( E! x e. A ph <-> E! y e. A ps )

Proof

Step	Hyp	Ref	Expression
1		cbvralvw.1	|- ( x = y -> ( ph <-> ps ) )
2		nfv	|- F/ y ph
3		nfv	|- F/ x ps
4	2 3 1	cbvreuw	|- ( E! x e. A ph <-> E! y e. A ps )