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Theorem con3ALT2 38204
Description: Contraposition. Alternate proof of con3 149. This proof is con3ALTVD 38621 automatically translated and minimized. (Contributed by Alan Sare, 21-Apr-2013.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
con3ALT2 ((𝜑𝜓) → (¬ 𝜓 → ¬ 𝜑))

Proof of Theorem con3ALT2
StepHypRef Expression
1 notnotr 125 . . 3 (¬ ¬ 𝜑𝜑)
21imim1i 63 . 2 ((𝜑𝜓) → (¬ ¬ 𝜑𝜓))
32con1d 139 1 ((𝜑𝜓) → (¬ 𝜓 → ¬ 𝜑))
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: (None)
  Copyright terms: Public domain W3C validator