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Theorem eldifbd 3009
Description: If a class is in the difference of two classes, it is not in the subtrahend. One-way deduction form of eldif 3006. (Contributed by David Moews, 1-May-2017.)
Hypothesis
Ref Expression
eldifbd.1  |-  ( ph  ->  A  e.  ( B 
\  C ) )
Assertion
Ref Expression
eldifbd  |-  ( ph  ->  -.  A  e.  C
)

Proof of Theorem eldifbd
StepHypRef Expression
1 eldifbd.1 . . 3  |-  ( ph  ->  A  e.  ( B 
\  C ) )
2 eldif 3006 . . 3  |-  ( A  e.  ( B  \  C )  <->  ( A  e.  B  /\  -.  A  e.  C ) )
31, 2sylib 120 . 2  |-  ( ph  ->  ( A  e.  B  /\  -.  A  e.  C
) )
43simprd 112 1  |-  ( ph  ->  -.  A  e.  C
)
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    /\ wa 102    e. wcel 1438    \ cdif 2994
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 579  ax-in2 580  ax-io 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070
This theorem depends on definitions:  df-bi 115  df-tru 1292  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-v 2621  df-dif 2999
This theorem is referenced by:  fidifsnen  6566  fiunsnnn  6577  fimax2gtri  6597  unfidisj  6612  ssfirab  6622  fnfi  6625  iunfidisj  6634  hashunlem  10177  hashxp  10199  zfz1isolemiso  10209  fsumconst  10811  fsumrelem  10828
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