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Theorem necon3bi 2557
Description: Contrapositive inference for inequality. (Contributed by NM, 1-Jun-2007.) (Proof shortened by Andrew Salmon, 25-May-2011.)
Hypothesis
Ref Expression
necon3bi.1
Assertion
Ref Expression
necon3bi

Proof of Theorem necon3bi
StepHypRef Expression
1 nne 2520 . . 3
2 necon3bi.1 . . 3
31, 2sylbi 187 . 2
43con1i 121 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   wi 4   wceq 1642   wne 2516
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-ne 2518
This theorem is referenced by:  r19.2zb  3640  nchoicelem8  6296
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