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Theorem dffr2 4849
Description: Alternate definition of well-founded relation. Similar to Definition 6.21 of [TakeutiZaring] p. 30. (Contributed by NM, 17-Feb-2004.) (Proof shortened by Andrew Salmon, 27-Aug-2011.) (Proof shortened by Mario Carneiro, 23-Jun-2015.)
Assertion
Ref Expression
dffr2
Distinct variable groups:   , , ,   , , ,

Proof of Theorem dffr2
StepHypRef Expression
1 df-fr 4843 . 2
2 rabeq0 3807 . . . . 5
32rexbii 2959 . . . 4
43imbi2i 312 . . 3
54albii 1640 . 2
61, 5bitr4i 252 1
Colors of variables: wff setvar class
Syntax hints:  -.wn 3  ->wi 4  <->wb 184  /\wa 369  A.wal 1393  =wceq 1395  =/=wne 2652  A.wral 2807  E.wrex 2808  {crab 2811  C_wss 3475   c0 3784   class class class wbr 4452  Frwfr 4840
This theorem is referenced by:  fr0  4863  dfepfr  4869  dffr3  5374
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1618  ax-4 1631  ax-5 1704  ax-6 1747  ax-7 1790  ax-10 1837  ax-11 1842  ax-12 1854  ax-13 1999  ax-ext 2435
This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371  df-tru 1398  df-ex 1613  df-nf 1617  df-sb 1740  df-clab 2443  df-cleq 2449  df-clel 2452  df-nfc 2607  df-ne 2654  df-ral 2812  df-rex 2813  df-rab 2816  df-v 3111  df-dif 3478  df-nul 3785  df-fr 4843
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