In: Advanced Math
Unless otherwise noted, all sets in this module are finite. Prove the following statements...
1. Let S = {0, 1, . . . , 23} and define f : Z→S by f(k) = r when 24|(k−r). If g : S→S is defined by (a) g(m) = f(7m) then g is injective and (b) g(m) = f(15m) then g is not injective.
2. Let f : A→B and g : B→C be injective. Then g ◦f : A→C is injective.
3. Let f : A→B and g : B→C be surjective. Then g ◦ f : A→C is surjective.
4. There is a surjection f : A→B such that f −1 : B→A is not a function.