Theorem neldifsnd

Description: The class A is not in ( B \ { A } ) . Deduction form. (Contributed by David Moews, 1-May-2017)

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

Proof

Step	Hyp	Ref	Expression
1		neldifsn	$$⊢\neg A\in \left(B\setminus \left\{A\right\}\right)$$
2	1	a1i	$$⊢\phi \to \neg A\in \left(B\setminus \left\{A\right\}\right)$$