Metamath Proof Explorer


Theorem nfaba1g

Description: Bound-variable hypothesis builder for a class abstraction. Usage of this theorem is discouraged because it depends on ax-13 . See nfaba1 for a version with a disjoint variable condition, but not requiring ax-13 . (Contributed by Mario Carneiro, 14-Oct-2016) (New usage is discouraged.)

Ref Expression
Assertion nfaba1g _ x y | x φ

Proof

Step Hyp Ref Expression
1 nfa1 x x φ
2 1 nfabg _ x y | x φ