This paper introduces the Cobham Recursive Set Functions (CRSF) as a version of polynomial time computable functions on general sets, based on a limited (bounded) form of ∈-recursion. This is inspired by Cobham’s classic definition of polynomial time functions based on limited recursion on notation. We introduce a new set composition function, and a new smash function for sets which allows poly...

We introduce the safe recursive set functions based on a Bellantoni-Cook style subclass of the primitive recursive set functions. We show that the functions computed by safe recursive set functions under a list encoding of finite strings by hereditarily finite sets, are exactly the polynomial growth rate functions computed by alternating exponential time Turing machines with polynomially many a...

Set functions which are unbounded on an algebra of sets arise naturally by taking the products of bounded operators and spectral measures acting on a space of square integrable functions. The purpose of this note is to show that, provided a certain regularity condition is satissed, there is a natural integration structure associated with such a set function and an auxiliary measure, so providin...