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Theorem pm3.14 488
Description: Theorem *3.14 of [WhiteheadRussell] p. 111. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm3.14 ((¬ φ ¬ ψ) → ¬ (φ ψ))

Proof of Theorem pm3.14
StepHypRef Expression
1 pm3.1 484 . 2 ((φ ψ) → ¬ (¬ φ ¬ ψ))
21con2i 112 1 ((¬ φ ¬ ψ) → ¬ (φ ψ))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4   wo 357   wa 358
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360
This theorem is referenced by: (None)
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