设 S 是一组 n 个元素。 S 上最大和最小等价关系的有序对数为：
(A) n 和 n
(B) n 2和 n
(C) n 2和 0
(D) n 和 1答案：(乙)
解释：
Consider an example set, S = (1,2,3)
Equivalence property follows, reflexive, symmetric
and transitive
Largest ordered set are s x s =
{ (1,1) (1,2) (1,3) (2,1) (2,2) (2,3) (3,1) (3,2)
(3,3) } which are 9 which equal to 3^2 = n^2
Smallest ordered set are { (1,1) (2,2) ( 3,3)}
which are 3 and equals to n. number of elements.这个问题的测验