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Theorem pm4.72 846
Description: Implication in terms of biconditional and disjunction. Theorem *4.72 of [WhiteheadRussell] p. 121. (Contributed by NM, 30-Aug-1993.) (Proof shortened by Wolf Lammen, 30-Jan-2013.)
Assertion
Ref Expression
pm4.72

Proof of Theorem pm4.72
StepHypRef Expression
1 olc 373 . . 3
2 pm2.621 397 . . 3
31, 2impbid2 195 . 2
4 orc 374 . . 3
5 bi2 189 . . 3
64, 5syl5 28 . 2
73, 6impbii 180 1
Colors of variables: wff setvar class
Syntax hints:   wi 4   wb 176   wo 357
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
This theorem depends on definitions:  df-bi 177  df-or 359
This theorem is referenced by:  bigolden  901  ssequn1  3433  ssunsn2  3865
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