Thus,
the total number of desired relations is three Example 24  Show that the number of equivalence relation in the set {1, 2, 3} containing
(1, 2) and (2, 1) is two Solution The smallest equivalence relation R1 containing (1, 2) and (2, 1) is {(1, 1),
(2, 2), (3, 3), (1, 2), (2, 1)} Now we are left with only 4 pairs namely (2, 3), (3, 2),
(1, 3) and (3, 1)