Question

The minimum number of elements that must be added to the relation $R=\\{(a, b),(b, c),(b, d)\\}$ on the set $\\{a, b, c, d\\}$ so that it is an equivalence relation, is _______

Answer 1

The correct answer is 13
Given R={(a,b),(b,c),(b,d)}
In order to make it equivalence relation as per given set, R must be
{(a,a),(b,b),(c,c),(d,d),(a,b),(b,a),(b,c),(c,b),
(b,d),(d,b),(a,c),(a,d),(c,d),(d,c),(c,a),(d,a)}
There already given so 13 more to be added.