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Theorem orabs 855
Description: Absorption of redundant internal disjunct. Compare Theorem *4.45 of [WhiteheadRussell] p. 119. (Contributed by NM, 21-Jun-1993.) (Proof shortened by Wolf Lammen, 28-Feb-2014.)
Assertion
Ref Expression
orabs

Proof of Theorem orabs
StepHypRef Expression
1 orc 385 . 2
21pm4.71ri 633 1
Colors of variables: wff setvar class
Syntax hints:  <->wb 184  \/wo 368  /\wa 369
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371
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