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Theorem eqsstr3d 3008
Description: Substitution of equality into a subclass relationship. (Contributed by NM, 25-Apr-2004.)
Hypotheses
Ref Expression
eqsstr3d.1 (𝜑𝐵 = 𝐴)
eqsstr3d.2 (𝜑𝐵𝐶)
Assertion
Ref Expression
eqsstr3d (𝜑𝐴𝐶)

Proof of Theorem eqsstr3d
StepHypRef Expression
1 eqsstr3d.1 . . 3 (𝜑𝐵 = 𝐴)
21eqcomd 2061 . 2 (𝜑𝐴 = 𝐵)
3 eqsstr3d.2 . 2 (𝜑𝐵𝐶)
42, 3eqsstrd 3007 1 (𝜑𝐴𝐶)
Colors of variables: wff set class
Syntax hints:  wi 4   = wceq 1259  wss 2945
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-5 1352  ax-7 1353  ax-gen 1354  ax-ie1 1398  ax-ie2 1399  ax-8 1411  ax-11 1413  ax-4 1416  ax-17 1435  ax-i9 1439  ax-ial 1443  ax-i5r 1444  ax-ext 2038
This theorem depends on definitions:  df-bi 114  df-nf 1366  df-sb 1662  df-clab 2043  df-cleq 2049  df-clel 2052  df-in 2952  df-ss 2959
This theorem is referenced by:  ssxpbm  4784  ssxp1  4785  ssxp2  4786  suppssof1  5756  tfrlemiubacc  5975  oaword1  6081  phplem4dom  6355  archnqq  6573
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