Presburger arithmetic, rational generating functions, and quasi-polynomials

A Presburger formula is a Boolean formula with variables in ℕ that can be written using addition, comparison (≤, =, etc.), Boolean operations (and, or, not), and quantifiers (∀ and ∃). We characterize sets that can be defined by a Presburger formula as exactly the sets whose characteristic functions can be represented by rational generating functions; a geometric characterization of such sets is also given. In addition, if p = (p 1,…,p n ) are a subset of the free variables in a Presburger formula, we can define a counting function g(p) to be the number of solutions to the formula, for a given p. We show that every counting function obtained in this way may be represented as, equivalently, either a piecewise quasi-polynomial or a rational generating function. In the full version of this paper, we also translate known computational complexity results into this setting and discuss open directions