 For purposes of capturing valid arguments concerning relations, the more important point is that functions need not be unary. For example, arithmetic division can be represented as a function from ordered pairs of numbers onto quotients: \(Q(x, y) = \frac{x}{y}\). Mappings can also be conditional. Consider the function that maps every even integer onto itself, and every odd integer onto its successor: \(C(x) = x\) if \(x\) is even, and \(x + 1\) otherwise; \(C(1) = 2\), \(C(2) = 2\), \(C(3) = 4\), etc. Frege held that propositions have parts that correspond to functions, and in particular, conditional functions that map arguments onto special values that reflect the truth or falsity of propositions/sentences. (As discussed below, Frege [1892] also distinguished these “truth values” from what he called Thoughts [Gedanken] or the “senses” [Sinnen] of propositions; where each of these sentential senses “presents” a truth value in certain way—i.e., as the value of a certain indicated function given a certain indicated argument.)