"Relations and Functions" stand out as crucial ... then R^-1 = {(2, 1), (3, 2)}. Here, the domain of R is equivalent to the range of R^-1, and vice versa. If (a, b) ∈ R, (b, c) ∈ R, then ...

Domain and Range of a Relation Let R be a relation from a set ... X is the subset of X containing all elements b related to a. A function f : X → Y is one-one (or injective) if f(x1) = f(x2) ...