Mahler measures of polynomials that are sums of a bounded number of monomials

Abstract

We study Laurent polynomials in any number of variables that are sums of at most $k$ monomials. We first show that the Mahler measure of such a polynomial is at least $h/2^{k-2}$, where $h$ is the height of the polynomial. Next, restricting to such polynomials having integer coefficients, we show that the set of logarithmic Mahler measures of the elements of this restricted set is a closed subset of the nonnegative real line, with $0$ being an isolated point of the set. In the final section, we discuss the extent to which such an integer polynomial of Mahler measure $1$ is determined by its $k$ coefficients.

arXiv comment7 pages. v2 corrects some minor errors in v1. Also, a result from [5] is quoted, instead of just being referred to (Theorem 3)