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Theorem necon3i 2310
Description: Contrapositive inference for inequality. (Contributed by NM, 9-Aug-2006.)
Hypothesis
Ref Expression
necon3i.1  |-  ( A  =  B  ->  C  =  D )
Assertion
Ref Expression
necon3i  |-  ( C  =/=  D  ->  A  =/=  B )

Proof of Theorem necon3i
StepHypRef Expression
1 necon3i.1 . 2  |-  ( A  =  B  ->  C  =  D )
2 id 19 . . 3  |-  ( ( A  =  B  ->  C  =  D )  ->  ( A  =  B  ->  C  =  D ) )
32necon3d 2306 . 2  |-  ( ( A  =  B  ->  C  =  D )  ->  ( C  =/=  D  ->  A  =/=  B ) )
41, 3ax-mp 7 1  |-  ( C  =/=  D  ->  A  =/=  B )
Colors of variables: wff set class
Syntax hints:    -> wi 4    = wceq 1296    =/= wne 2262
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 582  ax-in2 583
This theorem depends on definitions:  df-bi 116  df-ne 2263
This theorem is referenced by: (None)
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