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Theorem sseqtrd 2981
Description: Substitution of equality into a subclass relationship. (Contributed by NM, 25-Apr-2004.)
Hypotheses
Ref Expression
sseqtrd.1 (𝜑𝐴𝐵)
sseqtrd.2 (𝜑𝐵 = 𝐶)
Assertion
Ref Expression
sseqtrd (𝜑𝐴𝐶)

Proof of Theorem sseqtrd
StepHypRef Expression
1 sseqtrd.1 . 2 (𝜑𝐴𝐵)
2 sseqtrd.2 . . 3 (𝜑𝐵 = 𝐶)
32sseq2d 2973 . 2 (𝜑 → (𝐴𝐵𝐴𝐶))
41, 3mpbid 135 1 (𝜑𝐴𝐶)
Colors of variables: wff set class
Syntax hints:  wi 4   = wceq 1243  wss 2917
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-11 1397  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022
This theorem depends on definitions:  df-bi 110  df-nf 1350  df-sb 1646  df-clab 2027  df-cleq 2033  df-clel 2036  df-in 2924  df-ss 2931
This theorem is referenced by:  sseqtr4d  2982  resasplitss  5069  nnaword2  6087  erssxp  6129  phpm  6327  ioodisj  8861
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