Metamath Proof Explorer


Theorem ssrab2f

Description: Subclass relation for a restricted class. (Contributed by Glauco Siliprandi, 26-Jun-2021)

Ref Expression
Hypothesis ssrab2f.1 _ x A
Assertion ssrab2f x A | φ A

Proof

Step Hyp Ref Expression
1 ssrab2f.1 _ x A
2 nfrab1 _ x x A | φ
3 2 1 dfss3f x A | φ A x x A | φ x A
4 rabidim1 x x A | φ x A
5 3 4 mprgbir x A | φ A