Weyl groups and the Kostant game

Abstract

This paper establishes a novel combinatorial framework at the intersection of Lie theory and algebraic combinatorics, based on a generalization of the Kostant game. We begin by reviewing the foundations of root systems, the classification of Dynkin diagrams, and the structure of Weyl groups. Subsequently, we analyze the original Kostant game as a tool for generating positive roots, demonstrating its unique termination on simply-laced diagrams and its role in an alternative classification thereof. The main contribution of this work -- which, to our knowledge, has not been studied before -- is a multi-vertex generalization of the game that allows for the simultaneous modification of multiple vertices of a Dynkin diagram. We prove that the resulting configurations of this new game establish a natural bijection with the elements of the quotient W/W_J of Weyl groups by parabolic subgroups. This formalism is applied to problems in algebraic geometry, specifically addressing cases of the Mukai conjecture via Hilbert polynomials, and is accompanied by a computational implementation in Java. These results offer new combinatorial perspectives for studying root counting problems, the regularity of reduced word languages, and the construction of Young Tableaux.