Relation R on a set A is said to be a transitive relation on A iff:

(a,b) ∈ R and (b,c) ∈ R

⇒ (a,c) ∈ R ∀

a,b,c ∈ A

A={1,2,3}

⇒ R={(1,2),(2,3),(1,3)}