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Theorem nebi 2767
Description: Contraposition law for inequality. (Contributed by NM, 28-Dec-2008.)
Assertion
Ref Expression
nebi

Proof of Theorem nebi
StepHypRef Expression
1 id 22 . . 3
21necon3bid 2715 . 2
3 id 22 . . 3
43necon4bid 2716 . 2
52, 4impbii 188 1
Colors of variables: wff setvar class
Syntax hints:  <->wb 184  =wceq 1395  =/=wne 2652
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 185  df-ne 2654
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