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Theorem dfnot 1414
Description: Given falsum , we can define the negation of a wff as the statement that follows from assuming . (Contributed by Mario Carneiro, 9-Feb-2017.) (Proof shortened by Wolf Lammen, 21-Jul-2019.)
Assertion
Ref Expression
dfnot

Proof of Theorem dfnot
StepHypRef Expression
1 fal 1402 . 2
2 mtt 339 . 2
31, 2ax-mp 5 1
Colors of variables: wff setvar class
Syntax hints:  -.wn 3  ->wi 4  <->wb 184   wfal 1400
This theorem is referenced by:  inegd  1416  bj-godellob  34193
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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