(1) For a function f : A→ B, we call A the domain, B the co-domain, f(A) the range, and f−1(b), for any b ∈ B, the fiber (or inverse image or pre-image) of b. For a subset S of B, f−1(B) = ⋃ b∈S f −1(b). (2) The sizes of fibers can be used to characterize injectivity (each fiber has size at most one), surjectivity (each fiber is non-empty), and bijectivity (each fiber has size exactly one). (3)...