Given the set A = {1, 2, 3} and the set S = {(x, y) | x and y in A}. Consider the relation ≤ defined on S as follows: ((x1, y1) ≤ (x2, y2) if x1 ≤ x2 and y1 ≤ y2. Draw the directed graph of this relation. Show that it is a partial order. Explain why it is not a total order.