The left-greedy Lie algebra basis and star graphs

Abstract

We construct a basis for free Lie algebras via a ``left-greedy'' bracketing algorithm on Lyndon-Shirshov words. We use a new tool -- the configuration pairing between Lie brackets and graphs of Sinha-Walter -- to show that the left-greedy brackets form a basis. Our constructions further equip the left-greedy brackets with a dual monomial Lie coalgebra basis of ``star'' graphs. We end with a brief example using the dual basis of star graphs in a Lie algebra computation.