 The above construction may also be conceptualized in terms of strings and Cartesian products. The back-and-forth moves between functions of one and more than one variable—the “uncurrying” and “currying” of functions—algebraically corresponds to the two directions of residuation. For example, a function \(f\colon A\times B\rightarrow C\) may be represented by a function \(f^\prime\colon A \rightarrow B\rightarrow C\), and vice versa. Thus, without loss of generality, it is sufficient to consider unary functions. If \(a\) is a fixed element of the function space \(D_\infty\), then \(x = (a,x)\) holds when \(x\) is the fixed point of \(a\). In terms of tuples, the solution may be viewed as the infinite tuple \((a,(a,(a,\ldots\).