Theorem bnj524

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

	Ref	Expression
Hypotheses	bnj524.1	|- ( ph <-> ps )
	bnj524.2	|- A e. _V
Assertion	bnj524	|- ( [. A / x ]. ph <-> [. A / x ]. ps )

Proof

Step	Hyp	Ref	Expression
1		bnj524.1	|- ( ph <-> ps )
2		bnj524.2	|- A e. _V
3	1	sbcbii	|- ( [. A / x ]. ph <-> [. A / x ]. ps )