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Theorem coeq1 4542
Description: Equality theorem for composition of two classes. (Contributed by NM, 3-Jan-1997.)
Assertion
Ref Expression
coeq1 (𝐴 = 𝐵 → (𝐴𝐶) = (𝐵𝐶))

Proof of Theorem coeq1
StepHypRef Expression
1 coss1 4540 . . 3 (𝐴𝐵 → (𝐴𝐶) ⊆ (𝐵𝐶))
2 coss1 4540 . . 3 (𝐵𝐴 → (𝐵𝐶) ⊆ (𝐴𝐶))
31, 2anim12i 331 . 2 ((𝐴𝐵𝐵𝐴) → ((𝐴𝐶) ⊆ (𝐵𝐶) ∧ (𝐵𝐶) ⊆ (𝐴𝐶)))
4 eqss 3024 . 2 (𝐴 = 𝐵 ↔ (𝐴𝐵𝐵𝐴))
5 eqss 3024 . 2 ((𝐴𝐶) = (𝐵𝐶) ↔ ((𝐴𝐶) ⊆ (𝐵𝐶) ∧ (𝐵𝐶) ⊆ (𝐴𝐶)))
63, 4, 53imtr4i 199 1 (𝐴 = 𝐵 → (𝐴𝐶) = (𝐵𝐶))
Colors of variables: wff set class
Syntax hints:  wi 4  wa 102   = wceq 1285  wss 2983  ccom 4396
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-io 663  ax-5 1377  ax-7 1378  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-8 1436  ax-10 1437  ax-11 1438  ax-i12 1439  ax-bndl 1440  ax-4 1441  ax-17 1460  ax-i9 1464  ax-ial 1468  ax-i5r 1469  ax-ext 2065
This theorem depends on definitions:  df-bi 115  df-nf 1391  df-sb 1688  df-clab 2070  df-cleq 2076  df-clel 2079  df-nfc 2212  df-in 2989  df-ss 2996  df-br 3807  df-opab 3861  df-co 4401
This theorem is referenced by:  coeq1i  4544  coeq1d  4546  coi2  4888  relcnvtr  4891  funcoeqres  5209  ereq1  6201
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