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Theorem pm1.5 681
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 632 . . 3 (φ → (φ χ))
21olcd 652 . 2 (φ → (ψ (φ χ)))
3 olc 631 . . 3 (χ → (φ χ))
43orim2i 677 . 2 ((ψ χ) → (ψ (φ χ)))
52, 4jaoi 635 1 ((φ (ψ χ)) → (ψ (φ χ)))
Colors of variables: wff set class
Syntax hints:  wi 4   wo 628
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 629
This theorem depends on definitions:  df-bi 110
This theorem is referenced by:  or12  682
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