Theorem opid 3875

Description: The ordered pair <. A , A >. in Kuratowski's representation. (Contributed by FL, 28-Dec-2011.)

Hypothesis

Ref	Expression
opid.1	|- A e. _V

Assertion

Ref	Expression
opid	|- <. A , A >. = { { A } }

Proof of Theorem opid

Step	Hyp	Ref	Expression
1		dfsn2 3680	. . . 4 |- { A } = { A , A }
2	1	eqcomi 2233	. . 3 |- { A , A } = { A }
3	2	preq2i 3747	. 2 |- { { A } , { A , A } } = { { A } , { A } }
4		opid.1	. . 3 |- A e. _V
5	4, 4	dfop 3856	. 2 |- <. A , A >. = { { A } , { A , A } }
6		dfsn2 3680	. 2 |- { { A } } = { { A } , { A } }
7	3, 5, 6	3eqtr4i 2260	1 |- <. A , A >. = { { A } }

Syntax hints:   = wceq 1395   e. wcel 2200   _Vcvv 2799   {csn 3666   {cpr 3667   <.cop 3669

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 714  ax-5 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-10 1551  ax-11 1552  ax-i12 1553  ax-bndl 1555  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580  ax-i5r 1581  ax-ext 2211

This theorem depends on definitions:  df-bi 117  df-3an 1004  df-tru 1398  df-nf 1507  df-sb 1809  df-clab 2216  df-cleq 2222  df-clel 2225  df-nfc 2361  df-v 2801  df-un 3201  df-sn 3672  df-pr 3673  df-op 3675

This theorem is referenced by:  dmsnsnsng  5206  funopg  5352  funopsn  5817