*Alan Cobham's 1965 paper entitled "The intrinsic computational difficulty of functions" is one of the earliest mentions of the concept of the complexity class P, consisting of problems decidable in polynomial time. Cobham theorized that this complexity class was a good way to describe the set of feasibly computable problems. Any problem that cannot be contained in P is not feasible, but if a real-world problem can be solved by an algorithm existing in P, generally such an algorithm will eventually be discovered.*