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Theorem bi3 179
Description: Property of the biconditional connective. (Contributed by NM, 11-May-1999.)
Assertion
Ref Expression
bi3

Proof of Theorem bi3
StepHypRef Expression
1 df-bi 177 . . 3
2 simprim 142 . . 3
31, 2ax-mp 5 . 2
43expi 141 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   wi 4   wb 176
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
This theorem is referenced by:  impbii  180  impbidd  181  dfbi1  184  bisym  281
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