Estimating and computing Kronecker Coefficients: a vector partition function approach

Abstract

We study the Kronecker coefficients $g_{\lambda, \mu, \nu}$ via a formula that was described by Mishna, Rosas, and Sundaram, in which the coefficients are expressed as a signed sum of vector partition function evaluations. In particular, we use this formula to determine formulas to evaluate, bound, and estimate $g_{\lambda, \mu, \nu}$ in terms of the lengths of the partitions $\lambda, \mu$, and $\nu$. We describe a computational tool to compute Kronecker coefficients $g_{\lambda, \mu, \nu}$ with $\ell(\mu) \leq 2,\ \ell(\nu) \leq 4,\ \ell(\lambda) \leq 8$. We present a set of new vanishing conditions for the Kronecker coefficients by relating to the vanishing of the related atomic Kronecker coefficients, themselves given by a single vector partition function evaluation. We give a stable face of the Kronecker polyhedron for any positive integers $m,n$. Finally, we give upper bounds on both the atomic Kronecker coefficients and Kronecker coefficients.