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Theorem con4bii 288
Description: A contraposition inference. (Contributed by NM, 21-May-1994.)
Hypothesis
Ref Expression
con4bii.1
Assertion
Ref Expression
con4bii

Proof of Theorem con4bii
StepHypRef Expression
1 con4bii.1 . 2
2 notbi 286 . 2
31, 2mpbir 200 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   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:  2false  339  19.35  1600  2ralor  2780  gencbval  2903  eq0  3564  ab0  3569  uni0b  3916
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