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Theorem dfnotOLD 1415
Description: Obsolete proof of dfnot 1414 as of 21-Jul-2019. (Contributed by Mario Carneiro, 9-Feb-2017.) (New usage is discouraged.) (Proof modification is discouraged.)
Assertion
Ref Expression
dfnotOLD

Proof of Theorem dfnotOLD
StepHypRef Expression
1 pm2.21 108 . 2
2 id 22 . . 3
3 falim 1409 . . 3
42, 3ja 161 . 2
51, 4impbii 188 1
Colors of variables: wff setvar class
Syntax hints:  -.wn 3  ->wi 4  <->wb 184   wfal 1400
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 185  df-tru 1398  df-fal 1401
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