This is an inofficial mirror of http://metamath.tirix.org for personal testing of a visualizer extension only.

Metamath Proof Explorer


Theorem dfrab2

Description: Alternate definition of restricted class abstraction. (Contributed by NM, 20-Sep-2003) (Proof shortened by BJ, 22-Apr-2019)

Ref Expression
Assertion dfrab2 x A | φ = x | φ A

Proof

Step Hyp Ref Expression
1 dfrab3 x A | φ = A x | φ
2 incom A x | φ = x | φ A
3 1 2 eqtri x A | φ = x | φ A