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Theorem pm2.45 692
Description: Theorem *2.45 of [WhiteheadRussell] p. 106. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.45 (¬ (𝜑𝜓) → ¬ 𝜑)

Proof of Theorem pm2.45
StepHypRef Expression
1 orc 668 . 2 (𝜑 → (𝜑𝜓))
21con3i 597 1 (¬ (𝜑𝜓) → ¬ 𝜑)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wo 664
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-in1 579  ax-in2 580  ax-io 665
This theorem depends on definitions:  df-bi 115
This theorem is referenced by:  pm2.47  694  ioran  704  dn1dc  906  eueq3dc  2789
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