Theorem notnoti

Description: Inference associated with notnot . (Contributed by NM, 27-Feb-2008)

	Ref	Expression
Hypothesis	notnoti.1	⊢ 𝜑
Assertion	notnoti	⊢ ¬ ¬ 𝜑

Proof

Step	Hyp	Ref	Expression
1		notnoti.1	⊢ 𝜑
2		notnot	⊢ ( 𝜑 → ¬ ¬ 𝜑 )
3	1 2	ax-mp	⊢ ¬ ¬ 𝜑