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We introduce rectangular elements in the symmetric group. In the framework of PBW degenerations, we show that in type A the degenerate Schubert variety associated to a rectangular element is indeed a Schubert variety in a partial flag…

Representation Theory · Mathematics 2019-02-12 Rocco Chirivi' , Xin Fang , Ghislain Fourier

In this article, we investigate the toric Schubert varieties in partial flag varieties $G/P$ for a connected semisimple algebraic group $G$. Using Deodhar's decomposition of Richardson varieties and the work of Pasquier, we give an explicit…

Combinatorics · Mathematics 2026-05-05 Mahir Bilen Can , Arpita Nayek , Pinakinath Saha

We describe a method of computing equivariant and ordinary intersection cohomology of certain varieties with actions of algebraic tori, in terms of structure of the zero- and one-dimensional orbits. The class of varieties to which our…

Algebraic Geometry · Mathematics 2007-05-23 Tom Braden , Robert MacPherson

It is well known that the Einstein equation on a Riemannian flag manifold $(G/K,g)$ reduces to a algebraic system, if $g$ is a $G$-invariant metric. In this paper we described this system for all flag manifolds of a classical Lie group. We…

Differential Geometry · Mathematics 2014-11-13 Luciana Aparecida Alves , Neiton Pereira da Silva

The expansion of a Schubert polynomial into slide polynomials corresponds to a sum over sub-balls in the subword complex. There has been recent interest in other, coarser, expansions of Schubert polynomials. We extend the methods used in…

Combinatorics · Mathematics 2024-08-20 Thomas Bååth

Let V be a vector bundle on a scheme X endowed with a nondegenerate symplectic or orthogonal form. Let G be a Grassmannian bundle parametrizing maximal isotropic subbundles of V. The main goal of the paper is to give formulas for the…

alg-geom · Mathematics 2015-06-30 P. Pragacz , J. Ratajski

The main purpose of this article is to extend some of the ideas from Schubert calculus to the more general setting of Hamiltonian torus actions on compact symplectic manifolds with isolated fixed points. Given a generic component of the…

Symplectic Geometry · Mathematics 2009-09-10 R. F. Goldin , S. Tolman

We study combinatorial aspects of the Schubert calculus of the affine Grassmannian Gr associated with SL(n,C). Our main results are: 1) Pieri rules for the Schubert bases of H^*(Gr) and H_*(Gr), which expresses the product of a special…

Combinatorics · Mathematics 2008-11-23 Thomas Lam , Luc Lapointe , Jennifer Morse , Mark Shimozono

Our main theorems provide a single geometric setting in which polynomial representatives for Schubert classes in the integral cohomology ring of the flag manifold are determined uniquely, and have positive coefficients for geometric…

Algebraic Geometry · Mathematics 2010-04-26 Allen Knutson , Ezra Miller

Springer fibers are subvarieties of the flag variety parametrized by partitions; they are central objects of study in geometric representation theory. Schubert varieties are subvarieties of the flag variety that induce a well-known basis…

Combinatorics · Mathematics 2018-10-12 Martha Precup , Julianna Tymoczko

Schubert polynomials form a basis of all polynomials and appear in the study of cohomology rings of flag manifolds. The vanishing problem for Schubert polynomials asks if a coefficient of a Schubert polynomial is zero. We give a tableau…

Combinatorics · Mathematics 2021-09-13 Anshul Adve , Colleen Robichaux , Alexander Yong

Schubert polynomials were introduced in the context of the geometry of flag varieties. This paper investigates some of the connections not yet understood between several combinatorial structures for the construction of Schubert polynomials;…

Combinatorics · Mathematics 2007-05-23 Cristian Lenart

The orbits of the symplectic group acting on the type A flag variety are indexed by the fixed-point-free involutions in a finite symmetric group. The cohomology classes of the closures of these orbits have polynomial representatives…

Combinatorics · Mathematics 2019-09-30 Zachary Hamaker , Eric Marberg , Brendan Pawlowski

Consider the ring $\mathcal{S}$ of symmetric polynomials in $k$ variables over an arbitrary base ring $\mathbf{k}$. Fix $k$ scalars $a_{1},a_{2},\ldots,a_{k}\in\mathbf{k}$. Let $I$ be the ideal of $\mathcal{S}$ generated by…

Combinatorics · Mathematics 2021-09-24 Darij Grinberg

The polynomial ring $B$ in infinitely many indeterminates $(x_1,x_2,\ldots)$, with rational coefficients, has a vector space basis of Schur polynomials, parametrized by partitions. The goal of this note is to provide an explanation of the…

Algebraic Geometry · Mathematics 2021-07-16 Letterio Gatto

We propose a definition of equivariant (with respect to an Iwahori subgroup) $K$-theory of the formal power series model $\mathbf{Q}_{G}$ of semi-infinite flag manifold and prove the Pieri-Chevalley formula, which describes the product, in…

Quantum Algebra · Mathematics 2020-12-16 Syu Kato , Satoshi Naito , Daisuke Sagaki

We describe an explicit geometric Littlewood-Richardson rule, interpreted as deforming the intersection of two Schubert varieties so that they break into Schubert varieties. There are no restrictions on the base field, and all…

Algebraic Geometry · Mathematics 2007-05-23 Ravi Vakil

We give positive descriptions for certain Schubert structure constants $c_{u,v}^w$ for the full flag variety in Lie types $C$ and $D$. This is accomplished by first observing that a number of the $K=GL(n,\C)$-orbit closures on these flag…

Combinatorics · Mathematics 2012-07-02 Benjamin J. Wyser

Let G be a compact connected Lie group with a maximal torus T\subsetG. In the context of Schubert calculus we obtain a canonical presentation for the integral cohomology ring H^{\ast}(G/T) of the complete flag manifold G/T. The result have…

Algebraic Topology · Mathematics 2015-09-11 Haibao Duan , Xuezhi Zhao

Let G be a simple and simply-connected complex algebraic group, P \subset G a parabolic subgroup. We prove an unpublished result of D. Peterson which states that the quantum cohomology QH^*(G/P) of a flag variety is, up to localization, a…

Algebraic Geometry · Mathematics 2007-05-23 Thomas Lam , Mark Shimozono