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Theorem pm5.42 531
Description: Theorem *5.42 of [WhiteheadRussell] p. 125. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm5.42 ((φ → (ψχ)) ↔ (φ → (ψ → (φ χ))))

Proof of Theorem pm5.42
StepHypRef Expression
1 ibar 490 . . 3 (φ → (χ ↔ (φ χ)))
21imbi2d 307 . 2 (φ → ((ψχ) ↔ (ψ → (φ χ))))
32pm5.74i 236 1 ((φ → (ψχ)) ↔ (φ → (ψ → (φ χ))))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 176   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:  anc2l  538  imdistan  670
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