Theorem 19.9hOLD 1781

Description: Obsolete proof of 19.9h 1780 as of 5-Jan-2018. (Contributed by FL, 24-Mar-2007.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
19.9h.1	|- (ph -> A.xph)

Assertion

Ref	Expression
19.9hOLD	|- (E.xph <-> ph)

Proof of Theorem 19.9hOLD

Step	Hyp	Ref	Expression
1		19.9ht 1778	. . 3 |- (A.x(ph -> A.xph) -> (E.xph -> ph))
2		19.9h.1	. . 3 |- (ph -> A.xph)
3	1, 2	mpg 1548	. 2 |- (E.xph -> ph)
4		19.8a 1756	. 2 |- (ph -> E.xph)
5	3, 4	impbii 180	1 |- (E.xph <-> ph)

Syntax hints:   -> wi 4   <-> wb 176  A.wal 1540  E.wex 1541

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-11 1746

This theorem depends on definitions:  df-bi 177  df-ex 1542

This theorem is referenced by: (None)