Metamath Proof Explorer


Theorem reli

Description: The identity relation is a relation. Part of Exercise 4.12(p) of Mendelson p. 235. (Contributed by NM, 26-Apr-1998) (Revised by Mario Carneiro, 21-Dec-2013)

Ref Expression
Assertion reli Rel I

Proof

Step Hyp Ref Expression
1 df-id I = { ⟨ 𝑥 , 𝑦 ⟩ ∣ 𝑥 = 𝑦 }
2 1 relopabiv Rel I