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Theorem neorian 2888
Description: A De Morgan's law for inequality. (Contributed by NM, 18-May-2007.)
Assertion
Ref Expression
neorian  |-  ( ( A  =/=  B  \/  C  =/=  D )  <->  -.  ( A  =  B  /\  C  =  D )
)

Proof of Theorem neorian
StepHypRef Expression
1 df-ne 2795 . . 3  |-  ( A  =/=  B  <->  -.  A  =  B )
2 df-ne 2795 . . 3  |-  ( C  =/=  D  <->  -.  C  =  D )
31, 2orbi12i 543 . 2  |-  ( ( A  =/=  B  \/  C  =/=  D )  <->  ( -.  A  =  B  \/  -.  C  =  D
) )
4 ianor 509 . 2  |-  ( -.  ( A  =  B  /\  C  =  D )  <->  ( -.  A  =  B  \/  -.  C  =  D )
)
53, 4bitr4i 267 1  |-  ( ( A  =/=  B  \/  C  =/=  D )  <->  -.  ( A  =  B  /\  C  =  D )
)
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    <-> wb 196    \/ wo 383    /\ wa 384    = wceq 1483    =/= wne 2794
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 197  df-or 385  df-an 386  df-ne 2795
This theorem is referenced by:  neneor  2893  oeoa  7677  wemapso2lem  8457  recextlem2  10658  crne0  11013  crreczi  12989  gcdcllem3  15223  bezoutlem2  15257  dsmmacl  20085  txhaus  21450  itg1addlem2  23464  coeaddlem  24005  dcubic  24573  sibfof  30402  nrhmzr  41873
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