Theorem cbvriotav

Description: Change bound variable in a restricted description binder. Usage of this theorem is discouraged because it depends on ax-13 . Use the weaker cbvriotavw when possible. (Contributed by NM, 18-Mar-2013) (Revised by Mario Carneiro, 15-Oct-2016) (New usage is discouraged.)

	Ref	Expression
Hypothesis	cbvriotav.1	|- ( x = y -> ( ph <-> ps ) )
Assertion	cbvriotav	|- ( iota_ x e. A ph ) = ( iota_ y e. A ps )

Proof

Step	Hyp	Ref	Expression
1		cbvriotav.1	|- ( x = y -> ( ph <-> ps ) )
2		nfv	|- F/ y ph
3		nfv	|- F/ x ps
4	2 3 1	cbvriota	|- ( iota_ x e. A ph ) = ( iota_ y e. A ps )