Theorem prsstp23 3592

Description: A pair is a subset of an unordered triple containing its members. (Contributed by Jim Kingdon, 11-Aug-2018.)

Assertion

Ref	Expression
prsstp23	⊢ {𝐵, 𝐶} ⊆ {𝐴, 𝐵, 𝐶}

Proof of Theorem prsstp23

Step	Hyp	Ref	Expression
1		prsstp12 3590	. 2 ⊢ {𝐵, 𝐶} ⊆ {𝐵, 𝐶, 𝐴}
2		tprot 3535	. 2 ⊢ {𝐴, 𝐵, 𝐶} = {𝐵, 𝐶, 𝐴}
3	1, 2	sseqtr4i 3059	1 ⊢ {𝐵, 𝐶} ⊆ {𝐴, 𝐵, 𝐶}

Syntax hints:   ⊆ wss 2999  {cpr 3447  {ctp 3448

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070

This theorem depends on definitions:  df-bi 115  df-3or 925  df-tru 1292  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-v 2621  df-un 3003  df-in 3005  df-ss 3012  df-sn 3452  df-pr 3453  df-tp 3454

This theorem is referenced by:  sstpr  3601