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Theorem pm3.42 543
Description: Theorem *3.42 of [WhiteheadRussell] p. 113. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm3.42 ((ψχ) → ((φ ψ) → χ))

Proof of Theorem pm3.42
StepHypRef Expression
1 simpr 447 . 2 ((φ ψ) → ψ)
21imim1i 54 1 ((ψχ) → ((φ ψ) → χ))
Colors of variables: wff setvar class
Syntax hints:  wi 4   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-an 360
This theorem is referenced by: (None)
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