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Nao Komiyama

Publications and source records attributed to Nao Komiyama.

12 recordsLinked to original sources
arXiv2026

Associators in mould theory

By developing various techniques of mould theory and establishing a quasi-involutive reformulation of Drinfeld's associator set, we introduce $\mathsf{GARI}(\mathscr{F})_{\mathsf{as}+\mathsf{bal}}$, a mould theoretic formulation of Drinfeld's associator set. We give a mould-theoretical generalization of the result that associator relations imply double shuffle relations, namely, we explain that $\mathsf{GARI}(\mathscr{F})_{\mathsf{as}+\mathsf{bal}}$ is embedded into Ecalle's set $\mathsf{GARI}(\mathscr{F})_{\mathsf{as}\ast\mathsf{is}}$ which is a mould theoretic version of Racinet's double shuffle set.

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arXiv2026

On linearised and elliptic versions of the Kashiwara-Vergne Lie algebra

The goal of this article is to define a linearized or depth-graded version $\mathfrak{lkv}$, and a closely related elliptic version $\mathfrak{krv}_{ell}$, of the Kashiwara-Vergne Lie algebra $\mathfrak{krv}$ originally constructed by Alekseev and Torossian as the space of solutions to the linearized Kashiwara-Vergne problem. We show how the elliptic Lie algebra $\mathfrak{krv}_{ell}$ is related to earlier constructions of elliptic versions $\mathfrak{grt}_{ell}$ and $\mathfrak{ds}_{ell}$ of the Grothendieck-Teichmüller Lie algebra $\mathfrak{grt}$ and the double shuffle Lie algebra $\mathfrak{ds}$. In particular we show that there is an injective Lie morphism $\mathfrak{ds}_{ell}\hookrightarrow \mathfrak{krv}_{ell}$, and an injective Lie algebra morphism $\mathfrak{krv}\rightarrow \mathfrak{krv}_{ell}$ extending the known morphisms $\mathfrak{grt}\hookrightarrow\mathfrak{grt}_{ell}$ (Enriquez section) and $\mathfrak{ds}\rightarrow\mathfrak{ds}_{ell}$ (Écalle map).

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arXiv2025

Shuffle product for multiple zeta functions

In this paper, we investigate the shuffle product relations for Euler-Zagier multiple zeta functions as functional relations. To this end, we generalize the classical partial fraction decomposition formula and give two proofs. One is based on a connection formula for Gauss's hypergeometric functions, the other one is based on an elementary calculus. Though it is hard to write down explicit formula of the shuffle product relations for multiple zeta functions as in the case of multiple zeta values, we will provide inductive steps by using the zeta-functions of root systems. As an application, we get the functional double shuffle relations for multiple zeta functions and show that some relations for multiple zeta values/functions can be deduced from our results.

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arXiv2024

Notes on Kashiwara-Vergne and double shuffle Lie algebras

We explain the current situation of the relationship between the Kashiwara-Vergne Lie algebra $\mathfrak{krv}$ and the double shuffle Lie algebra $\mathfrak{dmr}$. We also show the validity of Ecalle's senary relation for small depths.

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arXiv2022

Kashiwara-Vergne and dihedral bigraded Lie algebras in mould theory

We introduce the Kashiwara-Vergne bigraded Lie algebra associated with a finite abelian group and give its mould theoretic reformulation. By using the mould theory, we show that it includes Goncharov's dihedral Lie algebra, which generalizes the result of Raphael and Schneps.

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arXiv2021

On properties of adari(pal) and ganit(pic)

The paper discusses properties of adari(pal) and ganit(pic) which are Ecalle's maps among certain sets of moulds related to the double shuffle relations of MZVs. We give self-contained proof of their basic properties which are exhibited in Ecalle's papers and partially proved in Schneps' paper.

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arXiv2020

Shuffle-type product formulae of desingularized values of multiple zeta-functions

It is known that there are infinitely many singularities of multiple zeta functions and the special values at non-positive integer points are indeterminate. In order to give a suitable rigorous meaning of the special values there, Furusho, Komori, Matsumoto and Tsumura introduced desingularized values by using their desingularization method to resolve all singularities. On the other hand, Ebrahimi-Fard, Manchon and Singer introduced renormalized values by the renormalization method à la Connes and Kreimer and they showed that the values fulfill the shuffle-type product formula. In this paper, we show the shuffle-type product formulae for desingularized values.

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arXiv2018

An equivalence between desingularized and renormalized values of multiple zeta functions at negative integers

It is known that the special values of multiple zeta functions at non-positive arguments are indeterminate in most cases due to the occurrences of infinitely many singularities. In order to give a suitable rigorous meaning of the special values there, Furusho, Komori, Matsumoto and Tsumura introduced the desingularized values by the desingularization method to resolve all singularities. While, Ebrahimi-Fard, Manchon and Singer introduced the renormalized values to keep the "shuffle" relation by the renormalization procedure à la Connes and Kreimer. In this paper, we reveal an equivalence, that is, an explicit interrelationship between these two values. As a corollary, we also obtain an explicit formula to describe renormalized values in terms of Bernoulli numbers.

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