Show that the relation R in the set {1, 2, 3} given by R = {(1, 1), (2, 2), (3, 3), (1, 2), (2, 3)} is reflexive but neither symmetric nor transitive.

Let A = {1. 2, 3}.
Let R = {(1, 1), (2, 2), (3, 3), (1, 2), (2, 3)}
Here R is reflexive as (a, a)∈ R ∀ a ∈ A.
R is not symmetric as (1, 2) ∈ R but (2, 1) ∈ R.
R is not transitive as (1.2) ∈ R and (2, 3) ∈ R but(1,3) ∈ R.
∴ R is a relation which is reflexive but neither symmetric not transitive.