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Theorem qexmid 1961
Description: Quantified "excluded middle." Exercise 9.2a of Boolos, p. 111, Computability and Logic. (Contributed by NM, 10-Dec-2000.)
Assertion
Ref Expression
qexmid  |-  E. x
( ph  ->  A. x ph )

Proof of Theorem qexmid
StepHypRef Expression
1 19.8a 1841 . 2  |-  ( A. x ph  ->  E. x A. x ph )
2119.35ri 1675 1  |-  E. x
( ph  ->  A. x ph )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4   A.wal 1379   E.wex 1597
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1603  ax-4 1616  ax-5 1689  ax-6 1732  ax-7 1774  ax-12 1838
This theorem depends on definitions:  df-bi 185  df-ex 1598
This theorem is referenced by: (None)
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