Duality-reflection formulas of multiple polylogarithms and their $\ell$-adic Galois analogues
Densuke Shiraishi
TL;DR
The paper derives duality-reflection formulas for both complex and $\\ell$-adic Galois multiple polylogarithms on $\\mathbb{P}^1\\setminus\\{0,1,\\infty\\}$, generalizing Oi--Ueno's reflection for polylogarithms and their specializations to multiple zeta values. It uses an algebraic chain-rule identity among associators arising from $S_3$-symmetry, namely $G_0(X,Y)(z;\\gamma)=G_0(Y,X)(1-z;\\gamma')\\cdot\\Phi(X,Y)$, and an analogous $\\ell$-adic equation with $\\mathfrak f^{z,\\gamma}_{\\sigma}(X,Y)$, to establish a unified framework for duality and reflection across the complex and $\\ell$-adic settings. The main results include a pair of functional equations (Main1 and Main2) that generalize known identities for multiple zeta values and their $\\ell$-adic Galois analogues, situating them within the KZ equation, Drinfeld associators, and Galois actions. The work points to potential $p$-adic extensions via Furusho's theory and broad arithmetic implications of symmetry-driven functional relations among polylogarithms.
Abstract
In the present paper, we derive formulas of complex and $\ell$-adic multiple polylogarithms, which have two aspects: a duality in terms of indexes and a reflection in terms of variables. We provide an algebraic proof of these formulas by using algebraic relations between associators arising from the $S_3$-symmetry of the projective line minus three points.
