Some explicit values of a $q$-multiple zeta function at roots of unity
Takao Komatsu
TL;DR
The paper studies explicit values of a finite $q$-multiple zeta function at roots of unity by introducing $q$-generalized $(r,s)$-Stirling numbers and connecting them to Bell polynomials and determinant expressions. It develops a framework that expresses $Z_n( abla_n;m,s)$ in terms of $Z_n( abla_n;1,s)$ via Bell polynomials and determinants, with an inversion formula linking these representations. Concrete results include explicit formulas for $s=2$ and $s=3$, and connections to degenerate Bernoulli numbers and $r$-Stirling numbers, enabling closed-form evaluations and structural insight. The work provides computable, structurally rich representations for finite $q$-MZVs at roots of unity, highlighting deep ties to classical combinatorial objects and suggesting avenues for extending the results to higher levels.
Abstract
In this paper, we give the values of a certain kind of $q$-multiple zeta functions at roots of unity. Various multiple zeta values have been proposed and studied by many researchers, but these multiple zeta values naturally arise from generalizations of Stirling numbers. It is interesting, but by no means easy, to show the values explicitly in certain cases. We give explicit formulas by using Bell polynomials, determinants, $r$-Stirling numbers, etc.
