Theorem 19.36v

Description: Version of 19.36 with a disjoint variable condition instead of a non-freeness hypothesis. (Contributed by NM, 18-Aug-1993) Reduce dependencies on axioms. (Revised by Wolf Lammen, 17-Jan-2020)

	Ref	Expression
Assertion	19.36v	|- ( E. x ( ph -> ps ) <-> ( A. x ph -> ps ) )

Proof

Step	Hyp	Ref	Expression
1		19.35	|- ( E. x ( ph -> ps ) <-> ( A. x ph -> E. x ps ) )
2		19.9v	|- ( E. x ps <-> ps )
3	2	imbi2i	|- ( ( A. x ph -> E. x ps ) <-> ( A. x ph -> ps ) )
4	1 3	bitri	|- ( E. x ( ph -> ps ) <-> ( A. x ph -> ps ) )