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Theorem preq12i 3498
 Description: Equality inference for unordered pairs. (Contributed by NM, 19-Oct-2012.)
Hypotheses
Ref Expression
preq1i.1 𝐴 = 𝐵
preq12i.2 𝐶 = 𝐷
Assertion
Ref Expression
preq12i {𝐴, 𝐶} = {𝐵, 𝐷}

Proof of Theorem preq12i
StepHypRef Expression
1 preq1i.1 . 2 𝐴 = 𝐵
2 preq12i.2 . 2 𝐶 = 𝐷
3 preq12 3495 . 2 ((𝐴 = 𝐵𝐶 = 𝐷) → {𝐴, 𝐶} = {𝐵, 𝐷})
41, 2, 3mp2an 417 1 {𝐴, 𝐶} = {𝐵, 𝐷}
 Colors of variables: wff set class Syntax hints:   = wceq 1285  {cpr 3423 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-tru 1288  df-nf 1391  df-sb 1688  df-clab 2070  df-cleq 2076  df-clel 2079  df-nfc 2212  df-v 2614  df-un 2988  df-sn 3428  df-pr 3429 This theorem is referenced by: (None)
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