Theorem bifal

Description: A contradiction is equivalent to falsehood. (Contributed by Mario Carneiro, 9-May-2015)

	Ref	Expression
Hypothesis	bifal.1	|- -. ph
Assertion	bifal	|- ( ph <-> F. )

Proof

Step	Hyp	Ref	Expression
1		bifal.1	|- -. ph
2		fal	|- -. F.
3	1 2	2false	|- ( ph <-> F. )