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Theorem pm2.45 386
Description: Theorem *2.45 of [WhiteheadRussell] p. 106. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.45 (¬ (φ ψ) → ¬ φ)

Proof of Theorem pm2.45
StepHypRef Expression
1 orc 374 . 2 (φ → (φ ψ))
21con3i 127 1 (¬ (φ ψ) → ¬ φ)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4   wo 357
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
This theorem is referenced by:  pm2.47  388  dn1  932  eueq3  3011
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