A Length Function for Weyl Groups of Extended Affine Root Systems of Type A1

Abstract

In this work, we study the concept of the length function and some of its combinatorial properties for the class of extended affine root systems of type A1. We introduce a notion of root basis for these root systems, and using a unique expression of the elements of the Weyl group with respect to a set of generators for the Weyl group, we calculate the length function with respect to a very specific root basis. © 2015 Academy of Mathematics and Systems Science, Chinese Academy of Sciences, and Suzhou University.