Séminaire Lotharingien de Combinatoire, 91B.31 (2024), 12 pp.

Masamichi Kuroda and Shuhei Tsujie

The Characteristic Quasi-Polynomials for Exceptional Well-Generated Complex Reflection Groups

Abstract. Kamiya, Takemura, and Terao initiated the theory of the characteristic quasi-polynomial of an integral arrangement, which is a function counting the elements in the complement of the arrangement modulo positive integers. The characteristic quasi-polynomials of crystallographic root systems exhibit many interesting properties. Recently, the authors extended the concept of the characteristic quasi-polynomials for arrangements over a Dedekind domain, where every residue ring with respect to nonzero ideal is finite. In this article, we investigate the characteristic quasi-polynomials for exceptional well-generated complex reflection groups, using the root systems over the rings of definition introduced by Lehrer and Taylor. We demonstrate that a specific relation between the Coxeter numbers and the LCM-periods of the characteristic quasi-polynomials is generalized in this context.


Received: November 15, 2023. Accepted: February 15, 2024. Final version: April 1, 2024.

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