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Theorem tpeq2 3511
Description: Equality theorem for unordered triples. (Contributed by NM, 13-Sep-2011.)
Assertion
Ref Expression
tpeq2 (𝐴 = 𝐵 → {𝐶, 𝐴, 𝐷} = {𝐶, 𝐵, 𝐷})

Proof of Theorem tpeq2
StepHypRef Expression
1 preq2 3502 . . 3 (𝐴 = 𝐵 → {𝐶, 𝐴} = {𝐶, 𝐵})
21uneq1d 3142 . 2 (𝐴 = 𝐵 → ({𝐶, 𝐴} ∪ {𝐷}) = ({𝐶, 𝐵} ∪ {𝐷}))
3 df-tp 3438 . 2 {𝐶, 𝐴, 𝐷} = ({𝐶, 𝐴} ∪ {𝐷})
4 df-tp 3438 . 2 {𝐶, 𝐵, 𝐷} = ({𝐶, 𝐵} ∪ {𝐷})
52, 3, 43eqtr4g 2142 1 (𝐴 = 𝐵 → {𝐶, 𝐴, 𝐷} = {𝐶, 𝐵, 𝐷})
Colors of variables: wff set class
Syntax hints:  wi 4   = wceq 1287  cun 2986  {csn 3430  {cpr 3431  {ctp 3432
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 1379  ax-7 1380  ax-gen 1381  ax-ie1 1425  ax-ie2 1426  ax-8 1438  ax-10 1439  ax-11 1440  ax-i12 1441  ax-bndl 1442  ax-4 1443  ax-17 1462  ax-i9 1466  ax-ial 1470  ax-i5r 1471  ax-ext 2067
This theorem depends on definitions:  df-bi 115  df-tru 1290  df-nf 1393  df-sb 1690  df-clab 2072  df-cleq 2078  df-clel 2081  df-nfc 2214  df-v 2617  df-un 2992  df-sn 3436  df-pr 3437  df-tp 3438
This theorem is referenced by:  tpeq2d  3514  fztpval  9419
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