Metamath Proof Explorer


Theorem relopab

Description: A class of ordered pairs is a relation. (Contributed by NM, 8-Mar-1995) Remove disjoint variable conditions. (Revised by Alan Sare, 9-Jul-2013) (Proof shortened by Mario Carneiro, 21-Dec-2013)

Ref Expression
Assertion relopab Rel x y | φ

Proof

Step Hyp Ref Expression
1 eqid x y | φ = x y | φ
2 1 relopabi Rel x y | φ