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Theorem 19.2 1674
Description: Theorem 19.2 of [Margaris] p. 89. Note: This proof is very different from Margaris' because we only have Tarski's FOL axiom schemes available at this point. See the later 19.2g 1776 for a more conventional proof. Revised to remove dependency on ax-8 1690. (Contributed by NM, 2-Aug-2017.) (Revised by Wolf Lammen, 4-Dec-2017.)
Assertion
Ref Expression
19.2  |-  ( A. x ph  ->  E. x ph )

Proof of Theorem 19.2
StepHypRef Expression
1 id 21 . . 3  |-  ( ph  ->  ph )
21exiftru 1672 . 2  |-  E. x
( ph  ->  ph )
3219.35i 1613 1  |-  ( A. x ph  ->  E. x ph )
Colors of variables: wff set class
Syntax hints:    -> wi 4   A.wal 1550   E.wex 1551
This theorem is referenced by:  19.8w  1675  19.39  1676  19.24  1677  19.34  1678  eusv2i  4755  extt  26189  pm10.251  27644  a9e2eq  28816  a9e2eqVD  29193
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1556  ax-5 1567  ax-9 1669
This theorem depends on definitions:  df-bi 179  df-an 362  df-ex 1552
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