Demazure product of permutations and hopping

Abstract

The Demazure product (also goes by the name of 0-Hecke product or the greedy product) is an associative operation on Coxeter groups with interesting properties and important applications. In this note, we study permutations and present an efficient way to compute the Demazure product of two permutations starting from their usual product and then applying a new operator we call a hopping operator. We also give an analogous result for the group of signed permutations.