Lyndon-Shirshov basis and anti-commutative algebras

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 Gröbner-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 Gröbner-Shirshov bases theory \cite{S62a2}, the set $Irr(S)$ is a linear basis of a free Lie algebra.