Theorem tpid1 3787

Description: One of the three elements of an unordered triple. (Contributed by NM, 7-Apr-1994.) (Proof shortened by Andrew Salmon, 29-Jun-2011.)

Hypothesis

Ref	Expression
tpid1.1	|- A e. _V

Assertion

Ref	Expression
tpid1	|- A e. { A , B , C }

Proof of Theorem tpid1

Step	Hyp	Ref	Expression
1		eqid 2231	. . 3 |- A = A
2	1	3mix1i 1196	. 2 |- ( A = A \/ A = B \/ A = C )
3		tpid1.1	. . 3 |- A e. _V
4	3	eltp 3721	. 2 |- ( A e. { A , B , C } <-> ( A = A \/ A = B \/ A = C ) )
5	2, 4	mpbir 146	1 |- A e. { A , B , C }

Syntax hints:   \/ w3o 1004   = wceq 1398   e. wcel 2202   _Vcvv 2803   {ctp 3675

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 717  ax-5 1496  ax-7 1497  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-8 1553  ax-10 1554  ax-11 1555  ax-i12 1556  ax-bndl 1558  ax-4 1559  ax-17 1575  ax-i9 1579  ax-ial 1583  ax-i5r 1584  ax-ext 2213

This theorem depends on definitions:  df-bi 117  df-3or 1006  df-tru 1401  df-nf 1510  df-sb 1811  df-clab 2218  df-cleq 2224  df-clel 2227  df-nfc 2364  df-v 2805  df-un 3205  df-sn 3679  df-pr 3680  df-tp 3681

This theorem is referenced by:  tpnz  3802