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Theorem oibabs 799
Description: Absorption of disjunction into equivalence. (Contributed by NM, 6-Aug-1995.) (Proof shortened by Wolf Lammen, 3-Nov-2013.)
Assertion
Ref Expression
oibabs

Proof of Theorem oibabs
StepHypRef Expression
1 pm2.67-2 633 . . . 4
21ibd 167 . . 3
3 olc 631 . . . . 5
43imim1i 54 . . . 4
5 ibibr 235 . . . 4
64, 5sylibr 137 . . 3
72, 6impbid 120 . 2
8 ax-1 5 . 2
97, 8impbii 117 1
Colors of variables: wff set class
Syntax hints:   wi 4   wb 98   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: (None)
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