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Theorem pm4.42r 866
Description: One direction of Theorem *4.42 of [WhiteheadRussell] p. 119. (Contributed by Jim Kingdon, 4-Aug-2018.)
Assertion
Ref Expression
pm4.42r (((φ ψ) (φ ¬ ψ)) → φ)

Proof of Theorem pm4.42r
StepHypRef Expression
1 ax-ia1 99 . 2 ((φ ψ) → φ)
2 ax-ia1 99 . 2 ((φ ¬ ψ) → φ)
31, 2jaoi 623 1 (((φ ψ) (φ ¬ ψ)) → φ)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4   wa 97   wo 616
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 617
This theorem depends on definitions:  df-bi 110
This theorem is referenced by: (None)
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