Question: If R is a relation on the set {1, 2, 3, 4} defined by R = {(1, 1), (2, 2), (3, 3), (4, 4), (1, 2), (2, 1)}, what type of relation is R?
Options:
Correct Answer: Both reflexive and symmetric
Solution:
R is reflexive because it contains all pairs (a, a) and symmetric because (1,2) implies (2,1).