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Theorem ssun2 3427
 Description: Subclass relationship for union of classes. (Contributed by NM, 30-Aug-1993.)
Assertion
Ref Expression
ssun2 A (BA)

Proof of Theorem ssun2
StepHypRef Expression
1 ssun1 3426 . 2 A (AB)
2 uncom 3408 . 2 (AB) = (BA)
31, 2sseqtri 3303 1 A (BA)
 Colors of variables: wff setvar class Syntax hints:   ∪ cun 3207   ⊆ wss 3257 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334 This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-v 2861  df-nin 3211  df-compl 3212  df-in 3213  df-un 3214  df-ss 3259 This theorem is referenced by:  ssun4  3429  elun2  3431  nsspssun  3488  unv  3578  un00  3586  snsspr2  3857  snsstp3  3860  unsneqsn  3887  pw1equn  4331  pw1eqadj  4332  nndisjeq  4429  sfinltfin  4535  vfinspss  4551  proj1op  4600  proj2op  4601  enadj  6060  ncdisjun  6136  ce0addcnnul  6179  sbthlem1  6203
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