Theorem preq2 3697

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 3696	. 2 |- ( A = B -> { A , C } = { B , C } )
2		prcom 3695	. 2 |- { C , A } = { A , C }
3		prcom 3695	. 2 |- { C , B } = { B , C }
4	1, 2, 3	3eqtr4g 2251	1 |- ( A = B -> { C , A } = { C , B } )

Syntax hints:   -> wi 4   = wceq 1364   {cpr 3620

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1458  ax-7 1459  ax-gen 1460  ax-ie1 1504  ax-ie2 1505  ax-8 1515  ax-10 1516  ax-11 1517  ax-i12 1518  ax-bndl 1520  ax-4 1521  ax-17 1537  ax-i9 1541  ax-ial 1545  ax-i5r 1546  ax-ext 2175

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1472  df-sb 1774  df-clab 2180  df-cleq 2186  df-clel 2189  df-nfc 2325  df-v 2762  df-un 3158  df-sn 3625  df-pr 3626

This theorem is referenced by:  preq12  3698  preq2i  3700  preq2d  3703  tpeq2  3706  preq12bg  3800  opeq2  3806  uniprg  3851  intprg  3904  prexg  4241  opth  4267  opeqsn  4282  relop  4813  funopg  5289  pr2ne  7254  hashprg  10882  bj-prexg  15473