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Theorem issetf 2732
 Description: A version of isset that does not require x and A to be distinct. (Contributed by Andrew Salmon, 6-Jun-2011.) (Revised by Mario Carneiro, 10-Oct-2016.)
Hypothesis
Ref Expression
issetf.1
Assertion
Ref Expression
issetf

Proof of Theorem issetf
StepHypRef Expression
1 isset 2731 . 2
2 issetf.1 . . . 4
32nfeq2 2396 . . 3
4 nfv 1629 . . 3
5 eqeq1 2259 . . 3
63, 4, 5cbvex 1877 . 2
71, 6bitri 242 1
 Colors of variables: wff set class Syntax hints:   wb 178  wex 1537   wceq 1619   wcel 1621  wnfc 2372  cvv 2727 This theorem is referenced by:  vtoclgf  2780  cla4imgft  2797 This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10  ax-5 1533  ax-6 1534  ax-7 1535  ax-gen 1536  ax-8 1623  ax-11 1624  ax-17 1628  ax-12o 1664  ax-10 1678  ax-9 1684  ax-4 1692  ax-16 1926  ax-ext 2234 This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-tru 1315  df-ex 1538  df-nf 1540  df-sb 1883  df-clab 2240  df-cleq 2246  df-clel 2249  df-nfc 2374  df-v 2729
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