Theorem nfabg

Description: Bound-variable hypothesis builder for a class abstraction. Usage of this theorem is discouraged because it depends on ax-13 . See nfab for a version with more disjoint variable conditions, but not requiring ax-13 . (Contributed by Mario Carneiro, 11-Aug-2016) (New usage is discouraged.)

	Ref	Expression
Hypothesis	nfabg.1	$$⊢Ⅎx\phi$$
Assertion	nfabg	$$⊢\underset{\_}{Ⅎ}x\left\{y|\phi \right\}$$

Proof

Step	Hyp	Ref	Expression
1		nfabg.1	$$⊢Ⅎx\phi$$
2	1	nfsabg	$$⊢Ⅎxz\in \left\{y|\phi \right\}$$
3	2	nfci	$$⊢\underset{\_}{Ⅎ}x\left\{y|\phi \right\}$$