Question

Is the following relation on A = {1, 2, 3, 4, 5} an equivalence relation? Determine the properties of an equivalence relation that the others lack: R = {(3, 4), (5, 5), (1, 1), (2, 2), (5, 2), (2, 5), (3, 1), (3, 3), (1, 3), (4, 3), (4, 4)}