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Theorem pm2.4 558
Description: Theorem *2.4 of [WhiteheadRussell] p. 106. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm2.4 ((φ (φ ψ)) → (φ ψ))

Proof of Theorem pm2.4
StepHypRef Expression
1 orc 374 . 2 (φ → (φ ψ))
2 id 19 . 2 ((φ ψ) → (φ ψ))
31, 2jaoi 368 1 ((φ (φ ψ)) → (φ ψ))
Colors of variables: wff setvar class
Syntax hints:  wi 4   wo 357
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
This theorem is referenced by: (None)
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