Theorem 19.9t 1573

Description: A closed version of 19.9 1575. (Contributed by NM, 5-Aug-1993.) (Revised by Mario Carneiro, 24-Sep-2016.) (Proof shortended by Wolf Lammen, 30-Dec-2017.)

Assertion

Ref	Expression
19.9t	|- ( F/ x ph -> ( E. x ph <-> ph ) )

Proof of Theorem 19.9t

Step	Hyp	Ref	Expression
1		df-nf 1390	. . 3 |- ( F/ x ph <-> A. x ( ph -> A. x ph ) )
2		19.9ht 1572	. . 3 |- ( A. x ( ph -> A. x ph ) -> ( E. x ph -> ph ) )
3	1, 2	sylbi 119	. 2 |- ( F/ x ph -> ( E. x ph -> ph ) )
4		19.8a 1522	. 2 |- ( ph -> E. x ph )
5	3, 4	impbid1 140	1 |- ( F/ x ph -> ( E. x ph <-> ph ) )

Syntax hints:   -> wi 4   <-> wb 103   A.wal 1282   F/wnf 1389   E.wex 1421

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-gen 1378  ax-ie1 1422  ax-ie2 1423  ax-4 1440

This theorem depends on definitions:  df-bi 115  df-nf 1390

This theorem is referenced by:  19.9d  1591  19.23t  1607  spimt  1664  exdistrfor  1721  sbequi  1760  sbft  1769  vtoclegft  2670  copsexg  3999