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Theorem pm2.47 692
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 pm2.45 690 . 2 (¬ (𝜑𝜓) → ¬ 𝜑)
21orcd 685 1 (¬ (𝜑𝜓) → (¬ 𝜑𝜓))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wo 662
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-in1 577  ax-in2 578  ax-io 663
This theorem depends on definitions:  df-bi 115
This theorem is referenced by: (None)
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