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Theorem preq2 3800
 Description: Equality theorem for unordered pairs. (Contributed by NM, 5-Aug-1993.)
Assertion
Ref Expression
preq2 (A = B → {C, A} = {C, B})

Proof of Theorem preq2
StepHypRef Expression
1 preq1 3799 . 2 (A = B → {A, C} = {B, C})
2 prcom 3798 . 2 {C, A} = {A, C}
3 prcom 3798 . 2 {C, B} = {B, C}
41, 2, 33eqtr4g 2410 1 (A = B → {C, A} = {C, B})
 Colors of variables: wff setvar class Syntax hints:   → wi 4   = wceq 1642  {cpr 3738 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334 This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-v 2861  df-nin 3211  df-compl 3212  df-un 3214  df-sn 3741  df-pr 3742 This theorem is referenced by:  preq12  3801  preq2i  3803  preq2d  3806  tpeq2  3809  uniprg  3906  intprg  3960  opkeq2  4060  preqr2g  4126  preq12bg  4128  enprmapc  6083
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