Metamath Proof Explorer

Theorem notfal

Description: A -. identity. (Contributed by Anthony Hart, 22-Oct-2010) (Proof shortened by Andrew Salmon, 13-May-2011)

		Ref	Expression
	Assertion	notfal	$⊢ \neg ⊥ \leftrightarrow ⊤$

Step	Hyp	Ref	Expression
1		fal	$⊢ \neg ⊥$
2	1	bitru	$⊢ \neg ⊥ \leftrightarrow ⊤$