The Weyl-Kac weight formula
arXiv:1802.06974
Abstract
We provide the first formulae for the weights of all simple highest weight modules over Kac-Moody algebras. For generic highest weights, we present a formula for the weights of simple modules similar to the Weyl-Kac character formula. For the remaining highest weights, the formula fails in a striking way, suggesting the existence of 'multiplicity-free' Macdonald identities for affine root systems.
12 pages, final version. This is an extended abstract of arXiv:1606.09640 in FPSAC 2017