Theorem 19.18 1091

Description: Theorem 19.18 of [Margaris] p. 90.

Assertion

Ref	Expression
19.18	|- (A.x(ph <-> ps) -> (E.xph <-> E.xps))

Proof of Theorem 19.18

Step	Hyp	Ref	Expression
1		bi1 155	. . . 4 |- ((ph <-> ps) -> (ph -> ps))
2	1	19.20i 1033	. . 3 |- (A.x(ph <-> ps) -> A.x(ph -> ps))
3		19.22 1080	. . 3 |- (A.x(ph -> ps) -> (E.xph -> E.xps))
4	2, 3	syl 10	. 2 |- (A.x(ph <-> ps) -> (E.xph -> E.xps))
5		bi2 156	. . . 4 |- ((ph <-> ps) -> (ps -> ph))
6	5	19.20i 1033	. . 3 |- (A.x(ph <-> ps) -> A.x(ps -> ph))
7		19.22 1080	. . 3 |- (A.x(ps -> ph) -> (E.xps -> E.xph))
8	6, 7	syl 10	. 2 |- (A.x(ph <-> ps) -> (E.xps -> E.xph))
9	4, 8	impbid 527	1 |- (A.x(ph <-> ps) -> (E.xph <-> E.xps))

Syntax hints:   -> wi 3   <-> wb 153  A.wal 995  E.wex 1021

This theorem is referenced by:  exbii 1092  19.19 1096  exbid 1146  exintrbi 1159

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7  ax-gen 1004  ax-4 1014  ax-5o 1016

This theorem depends on definitions:  df-bi 154  df-an 232  df-ex 1022

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