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Theorem unss2 3510
 Description: Subclass law for union of classes. Exercise 7 of [TakeutiZaring] p. 18. (Contributed by NM, 14-Oct-1999.)
Assertion
Ref Expression
unss2

Proof of Theorem unss2
StepHypRef Expression
1 unss1 3508 . 2
2 uncom 3483 . 2
3 uncom 3483 . 2
41, 2, 33sstr4g 3381 1
 Colors of variables: wff set class Syntax hints:   wi 4   cun 3310   wss 3312 This theorem is referenced by:  unss12  3511  ord3ex  4381  xpider  6967  fin1a2lem13  8284  canthp1lem2  8520  uniioombllem3  19469  volcn  19490  dvres2lem  19789  bnj1413  29341  bnj1408  29342 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1555  ax-5 1566  ax-17 1626  ax-9 1666  ax-8 1687  ax-6 1744  ax-7 1749  ax-11 1761  ax-12 1950  ax-ext 2416 This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-tru 1328  df-ex 1551  df-nf 1554  df-sb 1659  df-clab 2422  df-cleq 2428  df-clel 2431  df-nfc 2560  df-v 2950  df-un 3317  df-in 3319  df-ss 3326
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