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Theorem necon3bd 2328
Description: Contrapositive law deduction for inequality. (Contributed by NM, 2-Apr-2007.) (Proof rewritten by Jim Kingdon, 15-May-2018.)
Hypothesis
Ref Expression
necon3bd.1  |-  ( ph  ->  ( A  =  B  ->  ps ) )
Assertion
Ref Expression
necon3bd  |-  ( ph  ->  ( -.  ps  ->  A  =/=  B ) )

Proof of Theorem necon3bd
StepHypRef Expression
1 necon3bd.1 . . 3  |-  ( ph  ->  ( A  =  B  ->  ps ) )
21con3d 605 . 2  |-  ( ph  ->  ( -.  ps  ->  -.  A  =  B ) )
3 df-ne 2286 . 2  |-  ( A  =/=  B  <->  -.  A  =  B )
42, 3syl6ibr 161 1  |-  ( ph  ->  ( -.  ps  ->  A  =/=  B ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    = wceq 1316    =/= wne 2285
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 588  ax-in2 589
This theorem depends on definitions:  df-bi 116  df-ne 2286
This theorem is referenced by:  nelne1  2375  nelne2  2376  nssne1  3125  nssne2  3126  disjne  3386  difsn  3627  nbrne1  3917  nbrne2  3918  ac6sfi  6760  indpi  7118  zneo  9120
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