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Theorem ssneldd 3028
Description: If an element is not in a class, it is also not in a subclass of that class. Deduction form. (Contributed by David Moews, 1-May-2017.)
Hypotheses
Ref Expression
ssneld.1  |-  ( ph  ->  A  C_  B )
ssneldd.2  |-  ( ph  ->  -.  C  e.  B
)
Assertion
Ref Expression
ssneldd  |-  ( ph  ->  -.  C  e.  A
)

Proof of Theorem ssneldd
StepHypRef Expression
1 ssneldd.2 . 2  |-  ( ph  ->  -.  C  e.  B
)
2 ssneld.1 . . 3  |-  ( ph  ->  A  C_  B )
32ssneld 3027 . 2  |-  ( ph  ->  ( -.  C  e.  B  ->  -.  C  e.  A ) )
41, 3mpd 13 1  |-  ( ph  ->  -.  C  e.  A
)
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    e. wcel 1438    C_ wss 2999
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-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-11 1442  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-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-in 3005  df-ss 3012
This theorem is referenced by:  0nelrel  4484  addnqprlemfl  7118  addnqprlemfu  7119  mulnqprlemfl  7134  mulnqprlemfu  7135  cauappcvgprlemladdru  7215
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