Theorem nfcvd

Description: If x is disjoint from A , then x is not free in A . (Contributed by Mario Carneiro, 7-Oct-2016)

	Ref	Expression
Assertion	nfcvd	$$⊢\phi \to \underset{\_}{Ⅎ}xA$$

Proof

Step	Hyp	Ref	Expression
1		nfcv	$$⊢\underset{\_}{Ⅎ}xA$$
2	1	a1i	$$⊢\phi \to \underset{\_}{Ⅎ}xA$$