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Theorem pm4.55 480
Description: Theorem *4.55 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)
Assertion
Ref Expression
pm4.55

Proof of Theorem pm4.55
StepHypRef Expression
1 pm4.54 479 . . 3
21con2bii 322 . 2
32bicomi 193 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   wb 176   wo 357   wa 358
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 177  df-or 359  df-an 360
This theorem is referenced by: (None)
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