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Theorem ssuni 3913
 Description: Subclass relationship for class union. (Contributed by NM, 24-May-1994.) (Proof shortened by Andrew Salmon, 29-Jun-2011.)
Assertion
Ref Expression
ssuni

Proof of Theorem ssuni
Dummy variables are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 eleq2 2414 . . . . . . 7
21imbi1d 308 . . . . . 6
3 elunii 3896 . . . . . . 7
43expcom 424 . . . . . 6
52, 4vtoclga 2920 . . . . 5
65imim2d 48 . . . 4
76alimdv 1621 . . 3
8 dfss2 3262 . . 3
9 dfss2 3262 . . 3
107, 8, 93imtr4g 261 . 2
1110impcom 419 1
 Colors of variables: wff setvar class Syntax hints:   wi 4   wa 358  wal 1540   wceq 1642   wcel 1710   wss 3257  cuni 3891 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-ss 3259  df-uni 3892 This theorem is referenced by:  elssuni  3919  uniss2  3922
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