Theorem 19.23h 1521

Description: Theorem 19.23 of [Margaris] p. 90. (Contributed by NM, 5-Aug-1993.) (Revised by Mario Carneiro, 1-Feb-2015.)

Hypothesis

Ref	Expression
19.23h.1	|- ( ps -> A. x ps )

Assertion

Ref	Expression
19.23h	|- ( A. x ( ph -> ps ) <-> ( E. x ph -> ps ) )

Proof of Theorem 19.23h

Step	Hyp	Ref	Expression
1		19.23h.1	. . 3 |- ( ps -> A. x ps )
2	1	ax-gen 1472	. 2 |- A. x ( ps -> A. x ps )
3		19.23ht 1520	. 2 |- ( A. x ( ps -> A. x ps ) -> ( A. x ( ph -> ps ) <-> ( E. x ph -> ps ) ) )
4	2, 3	ax-mp 5	1 |- ( A. x ( ph -> ps ) <-> ( E. x ph -> ps ) )

Syntax hints:   -> wi 4   <-> wb 105   A.wal 1371   E.wex 1515

This theorem was proved from axioms:  ax-mp 5  ax-gen 1472  ax-ie2 1517

This theorem is referenced by:  alnex  1522  19.8a  1613  exlimih  1616  exlimdh  1619  nf2  1691  equs5or  1853  19.23v  1906  pm11.53  1919