 Another consequence of  Definition 2.3  is thus that each function \(f \in \mathbf{PR}\) possesses a specification which shows how it may be defined from the initial functions \(I_{\mathbf{PR}}\) in terms of a finite number of applications of composition and primitive recursion. This process may be illustrated by further considering the definitions of the functions \(\textit{add}(x,y)\) and \(\textit{mult}(x,y)\) given above.