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Theorem pm2.47 730
Description: Theorem *2.47 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.47 (¬ (𝜑𝜓) → (¬ 𝜑𝜓))

Proof of Theorem pm2.47
StepHypRef Expression
1 pm2.45 728 . 2 (¬ (𝜑𝜓) → ¬ 𝜑)
21orcd 723 1 (¬ (𝜑𝜓) → (¬ 𝜑𝜓))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wo 698
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-in1 604  ax-in2 605  ax-io 699
This theorem depends on definitions:  df-bi 116
This theorem is referenced by: (None)
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