Problem 4 Determine whether the following is a poset if it i

Problem 4

Determine whether the following is a poset, if it is give a topological sort of the poset, if it is not a poset state why it is not a poset and give a counterexample.

1. A = {a,b,c,d} R = {(a,a),(b,b),(c,c),(d,d),(a,b),(b,c),(c,a)}
2. A={a,b,c,d}R={(a,a),(b,b),(c,c),(d,d),(a,c),(c,d),(a,d),(b,c),(b,d)}