Theorem preq2 3654

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

Step	Hyp	Ref	Expression
1		preq1 3653	. 2 |- ( A = B -> { A , C } = { B , C } )
2		prcom 3652	. 2 |- { C , A } = { A , C }
3		prcom 3652	. 2 |- { C , B } = { B , C }
4	1, 2, 3	3eqtr4g 2224	1 |- ( A = B -> { C , A } = { C , B } )

Syntax hints:   -> wi 4   = wceq 1343   {cpr 3577

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-bndl 1497  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-tru 1346  df-nf 1449  df-sb 1751  df-clab 2152  df-cleq 2158  df-clel 2161  df-nfc 2297  df-v 2728  df-un 3120  df-sn 3582  df-pr 3583

This theorem is referenced by:  preq12  3655  preq2i  3657  preq2d  3660  tpeq2  3663  preq12bg  3753  opeq2  3759  uniprg  3804  intprg  3857  prexg  4189  opth  4215  opeqsn  4230  relop  4754  funopg  5222  pr2ne  7148  hashprg  10721  bj-prexg  13793