{ "id": "1809.08003", "version": "v1", "published": "2018-09-21T09:27:26.000Z", "updated": "2018-09-21T09:27:26.000Z", "title": "A classification of spherical Schubert varieties in the Grassmannian", "authors": [ "Reuven Hodges", "Venkatramani Lakshmibai" ], "comment": "22 pages", "categories": [ "math.RT", "math.AG", "math.CO" ], "abstract": "Let $L$ be a Levi subgroup of $GL_N$ which acts by left multiplication on a Schubert variety $X(w)$ in the Grassmannian $G_{d,N}$. We say that $X(w)$ is a spherical Schubert variety if $X(w)$ is a spherical variety for the action of $L$. In earlier work we provide a combinatorial description of the decomposition of the homogeneous coordinate ring of $X(w)$ into irreducible $L$-modules for the induced action of $L$. In this work we classify those decompositions into irreducible $L$-modules that are multiplicity-free. This is then applied towards giving a complete classification of the spherical Schubert varieties in the Grassmannian.", "revisions": [ { "version": "v1", "updated": "2018-09-21T09:27:26.000Z" } ], "analyses": { "subjects": [ "20G05", "20G20", "14B05", "14M27" ], "keywords": [ "spherical schubert variety", "grassmannian", "combinatorial description", "left multiplication", "earlier work" ], "note": { "typesetting": "TeX", "pages": 22, "language": "en", "license": "arXiv", "status": "editable" } } }