Truncations of the ring of number-theoretic functions

Abstract

We study the ring of all functions from the positive integers to some field. This ring, which we call \emph{the ring of number-theoretic functions}, is an inverse limit of the ``truncations'' Γ_n consisting of all functions f for which f(m)=0 whenever m > n. Each Γ_n is a zero-dimensional, finitely generated (K)-algebra, which may be expressed as the quotient of a finitely generated polynomial ring with a \emph{reversely stable} monomial ideal. Using the description of the free minimal resolution of stable ideals, given by Eliahou-Kervaire, and some additional arguments by Aramova-Herzog and Peeva, we give the Poincaré-Betti series for Γ_n.