Like Theorems 4.2 and 4.3, Theorem 4.4 is significant because it provides another machine-independent characterization of an important complexity class. Recall, however, that Cobham was working at a time when the mathematical status of the notion of feasibility was still under debate. So it is also reasonable to ask if the definition of \(\mathcal{F}\) can  be understood as providing an independently motivated analysis of feasible computability akin to the analyses which Church and Turing are often said to have provided for effective computability.