Theorem nexfal

Description: There does not exist a set such that F. is true. (Contributed by Anthony Hart, 13-Sep-2011)

	Ref	Expression
Assertion	nexfal	|- -. E. x F.

Proof

Step	Hyp	Ref	Expression
1		fal	|- -. F.
2	1	nex	|- -. E. x F.