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Theorem pm2.51 591
Description: Theorem *2.51 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.51 (¬ (𝜑𝜓) → (𝜑 → ¬ 𝜓))

Proof of Theorem pm2.51
StepHypRef Expression
1 ax-1 5 . . 3 (𝜓 → (𝜑𝜓))
21con3i 572 . 2 (¬ (𝜑𝜓) → ¬ 𝜓)
32a1d 22 1 (¬ (𝜑𝜓) → (𝜑 → ¬ 𝜓))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-in1 554  ax-in2 555
This theorem is referenced by: (None)
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