Lyndon-Shirshov basis and anti-commutative algebras

TL;DR

This paper presents a new approach to defining the Lyndon-Shirshov basis for free Lie algebras using anti-commutative Gr"obner-Shirshov bases, providing a clear algebraic structure and basis characterization.

Contribution

It introduces an anti-commutative Gr"obner-Shirshov basis for free Lie algebras, linking Lyndon-Shirshov words to algebraic basis construction.

Findings

Established a Gr"obner-Shirshov basis S for free Lie algebras.

Identified the set of Lyndon-Shirshov words as irreducible monomials.

Provided an algebraic framework for Lyndon-Shirshov basis construction.

Abstract

Chen, Fox, Lyndon 1958 \cite{CFL58} and Shirshov 1958 \cite{Sh58} introduced non-associative Lyndon-Shirshov words and proved that they form a linear basis of a free Lie algebra, independently. In this paper we give another approach to definition of Lyndon-Shirshov basis, i.e., we find an anti-commutative Gr\"{o}bner-Shirshov basis $S$ of a free Lie algebra such that $Irr(S)$ is the set of all non-associative Lyndon-Shirshov words, where $Irr(S)$ is the set of all monomials of $N(X)$, a basis of the free anti-commutative algebra on $X$, not containing maximal monomials of polynomials from $S$. Following from Shirshov's anti-commutative Gr\"{o}bner-Shirshov bases theory \cite{S62a2}, the set $Irr(S)$ is a linear basis of a free Lie algebra.