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Theorem necon1bbiiOLD 2696
Description: Obsolete proof of necon1bbii 2695 as of 24-Nov-2019. (Contributed by NM, 17-Mar-2007.) (Proof modification is discouraged.) (New usage is discouraged.)
Hypothesis
Ref Expression
necon1bbii.1  |-  ( A  =/=  B  <->  ph )
Assertion
Ref Expression
necon1bbiiOLD  |-  ( -. 
ph 
<->  A  =  B )

Proof of Theorem necon1bbiiOLD
StepHypRef Expression
1 df-ne 2627 . . 3  |-  ( A  =/=  B  <->  -.  A  =  B )
2 necon1bbii.1 . . 3  |-  ( A  =/=  B  <->  ph )
31, 2bitr3i 254 . 2  |-  ( -.  A  =  B  <->  ph )
43con1bii 332 1  |-  ( -. 
ph 
<->  A  =  B )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    <-> wb 187    = wceq 1437    =/= wne 2625
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 188  df-ne 2627
This theorem is referenced by: (None)
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