Tensor decomposition of Demazure crystals for symmetrizable Kac-Moody Lie algebras

Fuente: arXiv
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Main Author: Setia, Divya
Format: Preprint
Published: 2026
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author Setia, Divya
author_facet Setia, Divya
contents We study the tensor product of Demazure crystals for symmetrizable Kac-Moody Lie algebras. It is not necessary that the tensor product of Demazure crystals is isomorphic to a disjoint union of Demazure crystals. In this paper, we provide necessary and sufficient conditions for the decomposition of the tensor product of Demazure crystals as a disjoint union of Demazure crystals. Our results are the generalization of the results proved by Anthony Joseph and Takafumi Kouno. As an application, we obtain a sufficient condition when the product of Demazure characters is a linear combination of Demazure characters with nonnegative integer coefficients. In particular, we obtain a partial solution for the key positivity problem.
format Preprint
id arxiv_https___arxiv_org_abs_2601_18484
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Tensor decomposition of Demazure crystals for symmetrizable Kac-Moody Lie algebras
Setia, Divya
Representation Theory
Combinatorics
17B37, 17B10, 05E10
We study the tensor product of Demazure crystals for symmetrizable Kac-Moody Lie algebras. It is not necessary that the tensor product of Demazure crystals is isomorphic to a disjoint union of Demazure crystals. In this paper, we provide necessary and sufficient conditions for the decomposition of the tensor product of Demazure crystals as a disjoint union of Demazure crystals. Our results are the generalization of the results proved by Anthony Joseph and Takafumi Kouno. As an application, we obtain a sufficient condition when the product of Demazure characters is a linear combination of Demazure characters with nonnegative integer coefficients. In particular, we obtain a partial solution for the key positivity problem.
title Tensor decomposition of Demazure crystals for symmetrizable Kac-Moody Lie algebras
topic Representation Theory
Combinatorics
17B37, 17B10, 05E10
url https://arxiv.org/abs/2601.18484