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Theorem dfuni2 4017
 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 4016 . 2
2 exancom 1596 . . . 4
3 df-rex 2711 . . . 4
42, 3bitr4i 244 . . 3
54abbii 2548 . 2
61, 5eqtri 2456 1
 Colors of variables: wff set class Syntax hints:   wa 359  wex 1550   wceq 1652   wcel 1725  cab 2422  wrex 2706  cuni 4015 This theorem is referenced by:  nfuni  4021  nfunid  4022  unieq  4024  uniiun  4144 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 2417 This theorem depends on definitions:  df-bi 178  df-an 361  df-tru 1328  df-ex 1551  df-nf 1554  df-sb 1659  df-clab 2423  df-cleq 2429  df-rex 2711  df-uni 4016
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