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Theorem orordir 726
Description: Distribution of disjunction over disjunction. (Contributed by NM, 25-Feb-1995.)
Assertion
Ref Expression
orordir (((𝜑𝜓) ∨ 𝜒) ↔ ((𝜑𝜒) ∨ (𝜓𝜒)))

Proof of Theorem orordir
StepHypRef Expression
1 oridm 709 . . 3 ((𝜒𝜒) ↔ 𝜒)
21orbi2i 714 . 2 (((𝜑𝜓) ∨ (𝜒𝜒)) ↔ ((𝜑𝜓) ∨ 𝜒))
3 or4 723 . 2 (((𝜑𝜓) ∨ (𝜒𝜒)) ↔ ((𝜑𝜒) ∨ (𝜓𝜒)))
42, 3bitr3i 184 1 (((𝜑𝜓) ∨ 𝜒) ↔ ((𝜑𝜒) ∨ (𝜓𝜒)))
Colors of variables: wff set class
Syntax hints:  wb 103  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:  elznn0  8735
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