Theorem prtlem80

Description: Lemma for prter2 . (Contributed by Rodolfo Medina, 17-Oct-2010)

	Ref	Expression
Assertion	prtlem80	$$⊢A\in B\to \neg A\in \left(C\setminus \left\{A\right\}\right)$$

Proof

Step	Hyp	Ref	Expression
1		neldifsnd	$$⊢A\in B\to \neg A\in \left(C\setminus \left\{A\right\}\right)$$