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Theorem pm3.2im 155
Description: Theorem *3.2 of [WhiteheadRussell] p. 111, expressed with primitive connectives (see pm3.2 461). (Contributed by NM, 29-Dec-1992.) (Proof shortened by Josh Purinton, 29-Dec-2000.)
Assertion
Ref Expression
pm3.2im (𝜑 → (𝜓 → ¬ (𝜑 → ¬ 𝜓)))

Proof of Theorem pm3.2im
StepHypRef Expression
1 pm2.27 40 . 2 (𝜑 → ((𝜑 → ¬ 𝜓) → ¬ 𝜓))
21con2d 127 1 (𝜑 → (𝜓 → ¬ (𝜑 → ¬ 𝜓)))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem is referenced by:  jc  157  expi  159  expt  166
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