Theorem 19.24

Description: Theorem 19.24 of Margaris p. 90. (Contributed by NM, 12-Mar-1993)

	Ref	Expression
Assertion	19.24	|- ( ( A. x ph -> A. x ps ) -> E. x ( ph -> ps ) )

Proof

Step	Hyp	Ref	Expression
1		19.2	|- ( A. x ps -> E. x ps )
2	1	imim2i	|- ( ( A. x ph -> A. x ps ) -> ( A. x ph -> E. x ps ) )
3		19.35	|- ( E. x ( ph -> ps ) <-> ( A. x ph -> E. x ps ) )
4	2 3	sylibr	|- ( ( A. x ph -> A. x ps ) -> E. x ( ph -> ps ) )