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Theorem neeq12iOLD 2747
Description: Obsolete proof of neeq12i 2746 as of 25-Nov-2019. (Contributed by NM, 24-Jul-2012.) (Proof modification is discouraged.) (New usage is discouraged.)
Hypotheses
Ref Expression
neeq1i.1  |-  A  =  B
neeq12i.2  |-  C  =  D
Assertion
Ref Expression
neeq12iOLD  |-  ( A  =/=  C  <->  B  =/=  D )

Proof of Theorem neeq12iOLD
StepHypRef Expression
1 neeq12i.2 . . 3  |-  C  =  D
21neeq2i 2744 . 2  |-  ( A  =/=  C  <->  A  =/=  D )
3 neeq1i.1 . . 3  |-  A  =  B
43neeq1i 2742 . 2  |-  ( A  =/=  D  <->  B  =/=  D )
52, 4bitri 249 1  |-  ( A  =/=  C  <->  B  =/=  D )
Colors of variables: wff setvar class
Syntax hints:    <-> wb 184    = wceq 1395    =/= wne 2652
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1619  ax-4 1632  ax-ext 2435
This theorem depends on definitions:  df-bi 185  df-cleq 2449  df-ne 2654
This theorem is referenced by: (None)
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