Bijections

• Are the Positive Multiples of 17 and 11 in Bijection?
  The positive multiples of 17 and 11 are in bijection: match 17k with 11k for each positive integer k, and verify the map is one-to-one and onto.
• Show That the Identity Function on Any Set Is a Bijection
  For any set A, the identity map sends each element to itself, making it injective and surjective—and therefore bijective, even when A is empty.