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Theorem 19.9hOLD 1993
Description: Obsolete proof of 19.9h 1991 as of 14-Jul-2020. (Contributed by FL, 24-Mar-2007.) (Proof shortened by Wolf Lammen, 5-Jan-2018.) (Proof modification is discouraged.) (New usage is discouraged.)
Hypothesis
Ref Expression
19.9hOLD.1  |-  ( ph  ->  A. x ph )
Assertion
Ref Expression
19.9hOLD  |-  ( E. x ph  <->  ph )

Proof of Theorem 19.9hOLD
StepHypRef Expression
1 19.9hOLD.1 . . 3  |-  ( ph  ->  A. x ph )
21nfi 1682 . 2  |-  F/ x ph
3 19.9t 1989 . 2  |-  ( F/ x ph  ->  ( E. x ph  <->  ph ) )
42, 3ax-mp 5 1  |-  ( E. x ph  <->  ph )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    <-> wb 189   A.wal 1450   E.wex 1671   F/wnf 1675
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1677  ax-4 1690  ax-5 1766  ax-6 1813  ax-7 1859  ax-10 1932  ax-12 1950
This theorem depends on definitions:  df-bi 190  df-ex 1672  df-nf 1676
This theorem is referenced by: (None)
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