Theorem notnoti 606

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

Step	Hyp	Ref	Expression
1		negbi.1	. 2 ⊢ 𝜑
2		notnot 591	. 2 ⊢ (𝜑 → ¬ ¬ 𝜑)
3	1, 2	ax-mp 7	1 ⊢ ¬ ¬ 𝜑

Syntax hints:  ¬ wn 3

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-in1 576  ax-in2 577

This theorem is referenced by:  nbn3  648  fal  1291  ax-9  1464  neirr  2254  dfnul2  3253  dfnul3  3254  rab0  3273