Spherical Schubert varieties in GLn / P
Abstract
Let a general linear group act on a partial flag variety transitively, and consider the induced action of a Levi subgroup L. A Schubert variety is L−spherical if it is stable under the L-action and contains a dense open orbit of a Borel subgroup of L. It is toric if, in addition, L is a torus. In this paper, we give a combinatorial classification of L-spherical Schubert varieties in partial flag varieties. This is achieved by applying Lakshmibai-Seshadri paths forming crystal graphs of Demazure modules. Previously, Hodges and Lakshmibai classified L-spherical Schubert varieties in Grassmannians. L-spherical Schubert varieties in complete flag varieties were treated independently by Gao-Hodges-Yong and Can-Saha. Our classification generalizes and unifies these results.
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BibTeX
@misc{min2026spherical,
title = {{Spherical Schubert varieties in $GL_n / P$}},
author = {Jaewon Min},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.00321},
eprint = {2611.00321},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.00321},
}
RIS
TY - UNPB
TI - Spherical Schubert varieties in GL_n / P
AU - Jaewon Min
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.00321
UR - https://arxiv.org/abs/2611.00321
AB - Let a general linear group act on a partial flag variety transitively, and consider the induced action of a Levi subgroup L. A Schubert variety is L−spherical if it is stable under the L-action and contains a dense open orbit of a Borel subgroup of L. It is toric if, in addition, L is a torus. In this paper, we give a combinatorial classification of L-spherical Schubert varieties in partial flag varieties. This is achieved by applying Lakshmibai-Seshadri paths forming crystal graphs of Demazure modules. Previously, Hodges and Lakshmibai classified L-spherical Schubert varieties in Grassmannians. L-spherical Schubert varieties in complete flag varieties were treated independently by Gao-Hodges-Yong and Can-Saha. Our classification generalizes and unifies these results.
ER -