Consider the following relations: r1 = {(a, b) ∈ r2 ∣ a > b}, the greater than relation r2 = {(a, b) ∈ r2 ∣ a ≥ b}, the greater than or equal to relation r3 = {(a, b) ∈ r2 ∣ a < b}, the less than relation r4 = {(a, b) ∈ r2 ∣ a ≤ b}, the less than or equal to relation r5 = {(a, b) ∈ r2 ∣ a = b}, the equal to relation r6 = {(a, b) ∈ r2 ∣ a ≠ b}, the unequal to relation for these relations on the set of real numbers, find r1 ∪ r3.