Problem 2 (2 points each)

Determine whether each of these functions from {a, b, c, d} to itself is one-to-one.

a) f (a) = b, f (b) = a, f (c) = c, f (d) = d b) f (a) = b, f (b) = b, f (c) = d, f (d) = c c) f (a) = d, f (b) = b, f (c) = c, f (d) = d

Consider these functions from the set of students in a discrete mathematics class. Under what conditions is the function one-to-one if it assigns to a student their:

a) mobile phone number. b) student identification number. c) final grade in the class. d) home town.