On the relation of extended affine Weyl groups and indefinite Weyl groups

Abstract

Extended affine Weyl groups are the Weyl groups of root systems of a new class of Lie algebras called extended affine Lie algebras. In this paper we show that a (reduced) extended affine Weyl group is the homomorphic image of some indefinite Kac-Moody Weyl group where the homomorphism and its kernel are given explicitly. © 1999 Academic Press.