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Theorem dfuni2 4215
 Description: Alternate definition of class union. (Contributed by NM, 28-Jun-1998.)
Assertion
Ref Expression
dfuni2
Distinct variable group:   ,,

Proof of Theorem dfuni2
StepHypRef Expression
1 df-uni 4214 . 2
2 exancom 1716 . . . 4
3 df-rex 2779 . . . 4
42, 3bitr4i 255 . . 3
54abbii 2554 . 2
61, 5eqtri 2449 1
 Colors of variables: wff setvar class Syntax hints:   wa 370   wceq 1437  wex 1659   wcel 1867  cab 2405  wrex 2774  cuni 4213 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1665  ax-4 1678  ax-5 1748  ax-6 1794  ax-7 1838  ax-10 1886  ax-11 1891  ax-12 1904  ax-13 2052  ax-ext 2398 This theorem depends on definitions:  df-bi 188  df-an 372  df-tru 1440  df-ex 1660  df-nf 1664  df-sb 1787  df-clab 2406  df-cleq 2412  df-clel 2415  df-rex 2779  df-uni 4214 This theorem is referenced by:  nfuni  4219  nfunid  4220  unieq  4221  uniiun  4346
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