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Theorem tpidm12 4260
 Description: Unordered triple {𝐴, 𝐴, 𝐵} is just an overlong way to write {𝐴, 𝐵}. (Contributed by David A. Wheeler, 10-May-2015.)
Assertion
Ref Expression
tpidm12 {𝐴, 𝐴, 𝐵} = {𝐴, 𝐵}

Proof of Theorem tpidm12
StepHypRef Expression
1 dfsn2 4161 . . 3 {𝐴} = {𝐴, 𝐴}
21uneq1i 3741 . 2 ({𝐴} ∪ {𝐵}) = ({𝐴, 𝐴} ∪ {𝐵})
3 df-pr 4151 . 2 {𝐴, 𝐵} = ({𝐴} ∪ {𝐵})
4 df-tp 4153 . 2 {𝐴, 𝐴, 𝐵} = ({𝐴, 𝐴} ∪ {𝐵})
52, 3, 43eqtr4ri 2654 1 {𝐴, 𝐴, 𝐵} = {𝐴, 𝐵}
 Colors of variables: wff setvar class Syntax hints:   = wceq 1480   ∪ cun 3553  {csn 4148  {cpr 4150  {ctp 4152 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-9 1996  ax-10 2016  ax-11 2031  ax-12 2044  ax-13 2245  ax-ext 2601 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1483  df-ex 1702  df-nf 1707  df-sb 1878  df-clab 2608  df-cleq 2614  df-clel 2617  df-nfc 2750  df-v 3188  df-un 3560  df-pr 4151  df-tp 4153 This theorem is referenced by:  tpidm13  4261  tpidm23  4262  tpidm  4263  fntpb  6427  hashtpg  13205
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