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Theorem pm1.5 508
Description: Axiom *1.5 (Assoc) of [WhiteheadRussell] p. 96. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm1.5 ((φ (ψ χ)) → (ψ (φ χ)))

Proof of Theorem pm1.5
StepHypRef Expression
1 orc 374 . . 3 (φ → (φ χ))
21olcd 382 . 2 (φ → (ψ (φ χ)))
3 olc 373 . . 3 (χ → (φ χ))
43orim2i 504 . 2 ((ψ χ) → (ψ (φ χ)))
52, 4jaoi 368 1 ((φ (ψ χ)) → (ψ (φ χ)))
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:  or12  509
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