Schur Times Schubert via the Fomin-Kirillov Algebra

We study multiplication of any Schubert polynomial S[subscript w] by a Schur polynomial sλ (the Schubert polynomial of a Grassmannian permutation) and the expansion of this product in the ring of Schubert polynomials. We derive explicit nonnegative combinatorial expressions for the expansion coeffic...

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Main Authors: Meszaros, Karola, Panova, Greta, Postnikov, Alexander
Other Authors: Massachusetts Institute of Technology. Department of Mathematics
Format: Article
Language:en_US
Published: Electronic Journal of Combinatorics 2014
Online Access:http://hdl.handle.net/1721.1/89802
https://orcid.org/0000-0002-3964-8870
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author Meszaros, Karola
Panova, Greta
Postnikov, Alexander
author2 Massachusetts Institute of Technology. Department of Mathematics
author_facet Massachusetts Institute of Technology. Department of Mathematics
Meszaros, Karola
Panova, Greta
Postnikov, Alexander
author_sort Meszaros, Karola
collection MIT
description We study multiplication of any Schubert polynomial S[subscript w] by a Schur polynomial sλ (the Schubert polynomial of a Grassmannian permutation) and the expansion of this product in the ring of Schubert polynomials. We derive explicit nonnegative combinatorial expressions for the expansion coefficients for certain special partitions λ, including hooks and the 2×2 box. We also prove combinatorially the existence of such nonnegative expansion when the Young diagram of λ is a hook plus a box at the (2,2) corner. We achieve this by evaluating Schubert polynomials at the Dunkl elements of the Fomin-Kirillov algebra and proving special cases of the nonnegativity conjecture of Fomin and Kirillov. This approach works in the more general setup of the (small) quantum cohomology ring of the complex flag manifold and the corresponding (3-point) Gromov-Witten invariants. We provide an algebro-combinatorial proof of the nonnegativity of the Gromov-Witten invariants in these cases, and present combinatorial expressions for these coefficients.
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spelling mit-1721.1/898022022-10-01T09:26:41Z Schur Times Schubert via the Fomin-Kirillov Algebra Meszaros, Karola Panova, Greta Postnikov, Alexander Massachusetts Institute of Technology. Department of Mathematics Postnikov, Alexander We study multiplication of any Schubert polynomial S[subscript w] by a Schur polynomial sλ (the Schubert polynomial of a Grassmannian permutation) and the expansion of this product in the ring of Schubert polynomials. We derive explicit nonnegative combinatorial expressions for the expansion coefficients for certain special partitions λ, including hooks and the 2×2 box. We also prove combinatorially the existence of such nonnegative expansion when the Young diagram of λ is a hook plus a box at the (2,2) corner. We achieve this by evaluating Schubert polynomials at the Dunkl elements of the Fomin-Kirillov algebra and proving special cases of the nonnegativity conjecture of Fomin and Kirillov. This approach works in the more general setup of the (small) quantum cohomology ring of the complex flag manifold and the corresponding (3-point) Gromov-Witten invariants. We provide an algebro-combinatorial proof of the nonnegativity of the Gromov-Witten invariants in these cases, and present combinatorial expressions for these coefficients. National Science Foundation (U.S.) (Grant DMS-6923772) 2014-09-18T16:09:15Z 2014-09-18T16:09:15Z 2014-02 2013-08 Article http://purl.org/eprint/type/JournalArticle 1077-8926 http://hdl.handle.net/1721.1/89802 Meszaros, Karola, Greta Panova, and Alexander Postnikov. "Schur Times Schubert via the Fomin-Kirillov Algebra." Electronic Journal of Combinatorics, Volume 21, Issue 1 (2014). https://orcid.org/0000-0002-3964-8870 en_US http://www.combinatorics.org/ojs/index.php/eljc/article/view/v21i1p39 Electronic Journal of Combinatorics Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Electronic Journal of Combinatorics Electronic Journal of Combinatorics
spellingShingle Meszaros, Karola
Panova, Greta
Postnikov, Alexander
Schur Times Schubert via the Fomin-Kirillov Algebra
title Schur Times Schubert via the Fomin-Kirillov Algebra
title_full Schur Times Schubert via the Fomin-Kirillov Algebra
title_fullStr Schur Times Schubert via the Fomin-Kirillov Algebra
title_full_unstemmed Schur Times Schubert via the Fomin-Kirillov Algebra
title_short Schur Times Schubert via the Fomin-Kirillov Algebra
title_sort schur times schubert via the fomin kirillov algebra
url http://hdl.handle.net/1721.1/89802
https://orcid.org/0000-0002-3964-8870
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