Metamath Proof Explorer


Theorem ssrab2

Description: Subclass relation for a restricted class. (Contributed by NM, 19-Mar-1997) (Proof shortened by BJ and SN, 8-Aug-2024)

Ref Expression
Assertion ssrab2 x A | φ A

Proof

Step Hyp Ref Expression
1 elrabi y x A | φ y A
2 1 ssriv x A | φ A