{ "id": "2306.14485", "version": "v1", "published": "2023-06-26T07:52:53.000Z", "updated": "2023-06-26T07:52:53.000Z", "title": "Combinatorics of semi-toric degenerations of Schubert varieties in type C", "authors": [ "Naoki Fujita", "Yuta Nishiyama" ], "comment": "23 pages", "categories": [ "math.CO", "math.AG", "math.RT" ], "abstract": "An approach to Schubert calculus is to realize Schubert classes as concrete combinatorial objects such as Schubert polynomials. Using the polytope ring of the Gelfand-Tsetlin polytopes, Kiritchenko-Smirnov-Timorin realized each Schubert class as a sum of reduced Kogan faces. The first named author introduced a generalization of reduced Kogan faces to symplectic Gelfand-Tsetlin polytopes using a semi-toric degeneration of a Schubert variety, and extended the result of Kiritchenko-Smirnov-Timorin to type C case. In this paper, we introduce a combinatorial model to this type C generalization using a kind of pipe dream with self-crossings. As an application, we prove that the type C generalization can be constructed by skew mitosis operators.", "revisions": [ { "version": "v1", "updated": "2023-06-26T07:52:53.000Z" } ], "analyses": { "subjects": [ "05E10", "14M15", "14N15" ], "keywords": [ "schubert variety", "semi-toric degeneration", "reduced kogan faces", "combinatorics", "schubert class" ], "note": { "typesetting": "TeX", "pages": 23, "language": "en", "license": "arXiv", "status": "editable" } } }