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Theorem pm2.46 668
Description: Theorem *2.46 of [WhiteheadRussell] p. 106. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.46 (¬ (𝜑𝜓) → ¬ 𝜓)

Proof of Theorem pm2.46
StepHypRef Expression
1 olc 642 . 2 (𝜓 → (𝜑𝜓))
21con3i 572 1 (¬ (𝜑𝜓) → ¬ 𝜓)
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  wo 639
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-in1 554  ax-in2 555  ax-io 640
This theorem depends on definitions:  df-bi 114
This theorem is referenced by:  pm2.48  670  pm2.49  671  ioran  679  eueq3dc  2738  regexmidlem1  4286
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