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Theorem sseq1d 3027
Description: An equality deduction for the subclass relationship. (Contributed by NM, 14-Aug-1994.)
Hypothesis
Ref Expression
sseq1d.1  |-  ( ph  ->  A  =  B )
Assertion
Ref Expression
sseq1d  |-  ( ph  ->  ( A  C_  C  <->  B 
C_  C ) )

Proof of Theorem sseq1d
StepHypRef Expression
1 sseq1d.1 . 2  |-  ( ph  ->  A  =  B )
2 sseq1 3021 . 2  |-  ( A  =  B  ->  ( A  C_  C  <->  B  C_  C
) )
31, 2syl 14 1  |-  ( ph  ->  ( A  C_  C  <->  B 
C_  C ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 103    = wceq 1285    C_ wss 2974
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-5 1377  ax-7 1378  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-8 1436  ax-11 1438  ax-4 1441  ax-17 1460  ax-i9 1464  ax-ial 1468  ax-i5r 1469  ax-ext 2064
This theorem depends on definitions:  df-bi 115  df-nf 1391  df-sb 1687  df-clab 2069  df-cleq 2075  df-clel 2078  df-in 2980  df-ss 2987
This theorem is referenced by:  sseq12d  3029  eqsstrd  3034  snssg  3530  ssiun2s  3730  treq  3889  onsucsssucexmid  4278  funimass1  5007  feq1  5061  sbcfg  5076  fvmptssdm  5287  fvimacnvi  5313  nnsucsssuc  6136  ereq1  6179
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