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Theorem notnoti 115
Description: Infer double negation. (Contributed by NM, 27-Feb-2008.)
Hypothesis
Ref Expression
negbi.1 φ
Assertion
Ref Expression
notnoti ¬ ¬ φ

Proof of Theorem notnoti
StepHypRef Expression
1 negbi.1 . 2 φ
2 notnot1 114 . 2 (φ → ¬ ¬ φ)
31, 2ax-mp 5 1 ¬ ¬ φ
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem is referenced by:  nbn3  337  fal  1322  19.2OLD  1700  ax9dgen  1716  eqtfinrelk  4486  2p1e3c  6156
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