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Theorem pm5.62 889
Description: Theorem *5.62 of [WhiteheadRussell] p. 125. (Contributed by Roy F. Longton, 21-Jun-2005.)
Assertion
Ref Expression
pm5.62 (((φ ψ) ¬ ψ) ↔ (φ ¬ ψ))

Proof of Theorem pm5.62
StepHypRef Expression
1 exmid 404 . 2 (ψ ¬ ψ)
2 ordir 835 . 2 (((φ ψ) ¬ ψ) ↔ ((φ ¬ ψ) (ψ ¬ ψ)))
31, 2mpbiran2 885 1 (((φ ψ) ¬ ψ) ↔ (φ ¬ ψ))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wb 176   wo 357   wa 358
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 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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