Theorem cbvraldvaOLD

Description: Obsolete version of cbvraldva as of 9-Mar-2025. (Contributed by David Moews, 1-May-2017) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	cbvrexdva.1	|- ( ( ph /\ x = y ) -> ( ps <-> ch ) )
Assertion	cbvraldvaOLD	|- ( ph -> ( A. x e. A ps <-> A. y e. A ch ) )

Proof

Step	Hyp	Ref	Expression
1		cbvrexdva.1	|- ( ( ph /\ x = y ) -> ( ps <-> ch ) )
2		eqidd	|- ( ( ph /\ x = y ) -> A = A )
3	1 2	cbvraldva2	|- ( ph -> ( A. x e. A ps <-> A. y e. A ch ) )