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