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Theorem pm1.5 717
Description: Axiom *1.5 (Assoc) of [WhiteheadRussell] p. 96. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm1.5 ((𝜑 ∨ (𝜓𝜒)) → (𝜓 ∨ (𝜑𝜒)))

Proof of Theorem pm1.5
StepHypRef Expression
1 orc 668 . . 3 (𝜑 → (𝜑𝜒))
21olcd 688 . 2 (𝜑 → (𝜓 ∨ (𝜑𝜒)))
3 olc 667 . . 3 (𝜒 → (𝜑𝜒))
43orim2i 713 . 2 ((𝜓𝜒) → (𝜓 ∨ (𝜑𝜒)))
52, 4jaoi 671 1 ((𝜑 ∨ (𝜓𝜒)) → (𝜓 ∨ (𝜑𝜒)))
Colors of variables: wff set class
Syntax hints:  wi 4  wo 664
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 665
This theorem depends on definitions:  df-bi 115
This theorem is referenced by:  or12  718
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