ILE Home Intuitionistic Logic Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  ILE Home  >  Th. List  >  pm4.65r Structured version   GIF version

Theorem pm4.65r 782
Description: One direction of Theorem *4.65 of [WhiteheadRussell] p. 120. The converse holds in classical logic. (Contributed by Jim Kingdon, 28-Jul-2018.)
Assertion
Ref Expression
pm4.65r ((¬ φ ¬ ψ) → ¬ (¬ φψ))

Proof of Theorem pm4.65r
StepHypRef Expression
1 annimim 781 1 ((¬ φ ¬ ψ) → ¬ (¬ φψ))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4   wa 97
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-in1 544  ax-in2 545
This theorem is referenced by: (None)
  Copyright terms: Public domain W3C validator