Algorithm classifying roots of star-shaped Kac-Moody root systems

Abstract

For a star-shaped Kac-Moody root system, we provide an effective algorithm to obtain representatives of the Weyl group orbits of roots with a given norm and implement it as a computer program. We also explain the relationship between these orbits and Fuchsian differential equations on the Riemann sphere, as well as higher-dimensional Painleve-type equations.