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Theorem con4bid 284
Description: A contraposition deduction. (Contributed by NM, 21-May-1994.)
Hypothesis
Ref Expression
con4bid.1
Assertion
Ref Expression
con4bid

Proof of Theorem con4bid
StepHypRef Expression
1 con4bid.1 . . . 4
21biimprd 214 . . 3
32con4d 97 . 2
41biimpd 198 . 2
53, 4impcon4bid 196 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:  notbid  285  notbi  286  had0  1403  necon4abid  2580  sbcne12g  3154  isomin  5496
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