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Theorem 3orass 874
Description: Associative law for triple disjunction. (Contributed by NM, 8-Apr-1994.)
Assertion
Ref Expression
3orass ((φ ψ χ) ↔ (φ (ψ χ)))

Proof of Theorem 3orass
StepHypRef Expression
1 df-3or 872 . 2 ((φ ψ χ) ↔ ((φ ψ) χ))
2 orass 671 . 2 (((φ ψ) χ) ↔ (φ (ψ χ)))
31, 2bitri 173 1 ((φ ψ χ) ↔ (φ (ψ χ)))
Colors of variables: wff set class
Syntax hints:  wb 98   wo 616   w3o 870
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 617
This theorem depends on definitions:  df-bi 110  df-3or 872
This theorem is referenced by:  3orrot  877  3orcomb  880  3mix1  1059  sotritric  4031  sotritrieq  4032  ordtriexmid  4190  acexmidlemcase  5427  nntri3or  5983  nntri2  5984
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