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Theorem notnotnot 615
Description: Triple negation. (Contributed by Jim Kingdon, 28-Jul-2018.)
Assertion
Ref Expression
notnotnot

Proof of Theorem notnotnot
StepHypRef Expression
1 notnot1 547 . . 3
21con3i 549 . 2
3 notnot1 547 . 2
42, 3impbii 117 1
Colors of variables: wff set class
Syntax hints:   wn 3   wb 98
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia2 100  ax-ia3 101  ax-in1 532  ax-in2 533
This theorem depends on definitions:  df-bi 110
This theorem is referenced by:  stabnot  729  testbitestn  732  dcnbidcnn  7006
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