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Theorem dfnul3 3553
 Description: Alternate definition of the empty set. (Contributed by NM, 25-Mar-2004.)
Assertion
Ref Expression
dfnul3

Proof of Theorem dfnul3
StepHypRef Expression
1 pm3.24 852 . . . . 5
2 eqid 2353 . . . . 5
31, 22th 230 . . . 4
43con1bii 321 . . 3
54abbii 2465 . 2
6 dfnul2 3552 . 2
7 df-rab 2623 . 2
85, 6, 73eqtr4i 2383 1
 Colors of variables: wff setvar class Syntax hints:   wn 3   wa 358   wceq 1642   wcel 1710  cab 2339  crab 2618  c0 3550 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 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-rab 2623  df-v 2861  df-nin 3211  df-compl 3212  df-in 3213  df-dif 3215  df-nul 3551 This theorem is referenced by:  difidALT  3619
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