Question

What should be checked to determine whether a relation is reflexive?

Options

• Whether every \((a,b)\) has the reverse pair \((b,a)\)

• Whether \((a,b)\) and \((b,c)\) together give \((a,c)\)

• Whether every \((a,a)\) is present in the relation

• Whether the relation contains no ordered pairs

Answer 1

Reflexivity is tested using self-pairs. Every pair of the form \((a,a)\), for all \(a\in A\), must be present in the relation.