Standard Relations of Multiple Polylogarithm Values at Roots of Unity

TL;DR

This paper investigates the algebraic relations among multiple polylogarithm values at roots of unity, establishing bounds on their dimensions and identifying the limitations of standard relations through theoretical and computational analysis.

Contribution

It introduces the concept of standard relations for MPVs, provides bounds on their dimensions, and highlights the potential existence of additional relations beyond standard ones.

Findings

Standard relations give upper bounds on MPV dimensions.

For prime-power levels, bounds align with Deligne and Goncharov's predictions.

Evidence suggests the existence of additional, non-standard relations.

Abstract

Let $N$ be a positive integer. In this paper we shall study the special values of multiple polylogarithms at $N$th roots of unity, called multiple polylogarithm values (MPVs) of level $N$. These objects are generalizations of multiple zeta values and alternating Euler sums, which was studied by Euler, and more recently, many mathematicians and theoretical physicists.. Our primary goal in this paper is to investigate the relations among the MPVs of the same weight and level by using the regularized double shuffle relations, regularized distribution relations, lifted versions of such relations from lower weights, and seeded relations which are produced by relations of weight one MPVs. We call relations from the above four families \emph{standard}. Let $d(w,N)$ be the $\Q$-dimension of $\Q$-span of all MPVs of weight $w$ and level $N$. Then we obtain upper bound for $d(w,N)$ by the standard relations which in general are no worse or no better than the one given by Deligne and Goncharov depending on whether $N$ is a prime-power or not, respectively, except for 2- and 3-powers, in which case standard relations seem to be often incomplete whereas Deligne shows that their bound should be sharp by a variant of Grothedieck's period conjecture. This suggests that in general there should be other linear relations among MPVs besides the standard relations, some of which are written down in this paper explicitly with good numerical verification. We also provide a few conjectures which are supported by our computational evidence.