Also, R is not symmetric,
as (1, 2) ∈ R but (2, 1) ∉ R Similarly, R is not transitive, as (1, 2) ∈ R and (2, 3) ∈ R
but (1, 3) ∉ R Example 5 Show that the relation R in the set Z of integers given by
R = {(a, b) : 2 divides a – b}
is an equivalence relation Solution R is reflexive, as 2 divides (a – a) for all a ∈ Z