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Theorem notnoti 635
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 notnot 619 . 2 (𝜑 → ¬ ¬ 𝜑)
31, 2ax-mp 5 1 ¬ ¬ 𝜑
Colors of variables: wff set class
Syntax hints:  ¬ wn 3
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-in1 604  ax-in2 605
This theorem is referenced by:  nbn3  690  fal  1339  ax-9  1512  neirr  2318  dfnul2  3369  dfnul3  3370  rab0  3395
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