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Theorem necon3biOLD 2687
Description: Obsolete proof of necon3bi 2686 as of 22-Nov-2019. (Contributed by NM, 1-Jun-2007.) (Proof shortened by Andrew Salmon, 25-May-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
Hypothesis
Ref Expression
necon3bi.1  |-  ( A  =  B  ->  ph )
Assertion
Ref Expression
necon3biOLD  |-  ( -. 
ph  ->  A  =/=  B
)

Proof of Theorem necon3biOLD
StepHypRef Expression
1 nne 2658 . . 3  |-  ( -.  A  =/=  B  <->  A  =  B )
2 necon3bi.1 . . 3  |-  ( A  =  B  ->  ph )
31, 2sylbi 195 . 2  |-  ( -.  A  =/=  B  ->  ph )
43con1i 129 1  |-  ( -. 
ph  ->  A  =/=  B
)
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4    = 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
This theorem is referenced by: (None)
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