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In this paper, we first discuss the topological properties of projective Stiefel manifolds, we compute their cohomology rings and classify their cohomology endomorphisms; Then by embedding the flag manifold of a classical Lie group into its…

Algebraic Topology · Mathematics 2015-12-31 Zhao Xu-an , Gao Hongzhu

We use Bott-Samelson resolutions of Schubert varieties in Grassmannians along with equiariant localization techniques to show that the factorial Schur functions and the factorial Grothendieck polynomials represent Schubert classes in…

Algebraic Geometry · Mathematics 2021-10-14 David Oetjen

The main classical result of Schubert calculus is that multiplication rules for the basis of Schubert cycles inside the cohomology ring of the Grassmannian $G(n,m)$ are the same as multiplication rules for the basis of Schur polynomials in…

Representation Theory · Mathematics 2024-07-24 Antoine Labelle

Present notes can be viewed as an attempt to extend the notion of Schubert/Grothendieck polynomial to the context of an arbitrary algebraic oriented cohomology theory and, hence, of a commutative one-dimensional formal group law.

Rings and Algebras · Mathematics 2014-06-05 Kirill Zainoulline

Let G be a compact connected Lie group and H, the centralizer of a one-parameter subgroup in G. Combining the ideas of Bott-Samelson resulotions of Schubert varieties and the enumerative formula on a twisted products of 2-spheres obatained…

Algebraic Geometry · Mathematics 2014-04-02 Haibao Duan

The orbits of the orthogonal and symplectic groups on the flag variety are in bijection, respectively, with the involutions and fixed-point-free involutions in the symmetric group $S_n$. Wyser and Yong have described polynomial…

Combinatorics · Mathematics 2018-08-29 Zachary Hamaker , Eric Marberg , Brendan Pawlowski

We obtain an algorithm computing the Chern-Schwartz-MacPherson (CSM) classes of Schubert cells in a generalized flag manifold G/B. In analogy to how the ordinary divided difference operators act on Schubert classes, each CSM class of a…

Algebraic Geometry · Mathematics 2019-02-20 Paolo Aluffi , Leonardo C. Mihalcea

Let F be the flag variety of a complex semi-simple group G, let H be an algebraic subgroup of G acting on F with finitely many orbits, and let V be an H-orbit closure in F. Expanding the cohomology class of V in the basis of Schubert…

Algebraic Geometry · Mathematics 2007-05-23 Michel Brion

We give a new proof that three families of polynomials coincide: the double Schubert polynomials of Lascoux and Sch\"utzenberger defined by divided difference operators, the pipe dream polynomials of Bergeron and Billey, and the equivariant…

Combinatorics · Mathematics 2022-02-08 Allen Knutson

Let $G = GL(n)$ and $K = GL(p) \times GL(q)$ with $p+q=n$, where the groups are taken over $\C$. In this paper we study a certain family of $K$-orbit closures on the flag variety $X$ of $G$. The geometry of these orbit closures plays a…

Algebraic Geometry · Mathematics 2026-03-31 William Graham , Minyoung Jeon , Scott Joseph Larson

We study the torus equivariant Schubert classes of the Grassmannian of non-maximal isotropic subspaces in a symplectic vector space. We prove a formula that expresses each of those classes as a sum of multi Schur-Pfaffians, whose entries…

Algebraic Geometry · Mathematics 2015-06-18 Takeshi Ikeda , Tomoo Matsumura

The cohomology of the affine flag variety of a complex reductive group is a comodule over the cohomology of the affine Grassmannian. We give positive formulae for the coproduct of an affine Schubert class in terms of affine Stanley classes…

Combinatorics · Mathematics 2020-09-22 Thomas Lam , Seung Jin Lee , 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

We describe the integral cohomology rings of the flag manifolds of types B_n, D_n, G_2 and F_4 in terms of their Schubert classes. The main tool is the divided difference operators of Bernstein-Gelfand-Gelfand and Demazure. As an…

Algebraic Topology · Mathematics 2008-07-25 Masaki Nakagawa

Flag domains are open orbits of real semisimple Lie groups in flag manifolds of their complexifications. Certain group theoretically defined compact complex submanifolds, which are regarded as cycles, are of basic importance for their…

Algebraic Geometry · Mathematics 2014-11-04 Ana-Maria Brecan

We classify all products of flag varieties with finitely many orbits under the diagonal action of the general linear group. We also classify the orbits in each case and construct explicit representatives. This generalizes the classical…

Algebraic Geometry · Mathematics 2016-09-07 Peter Magyar , Jerzy Weyman , Andrei Zelevinsky

Let $\mathcal S$ be a single condition Schubert variety with an arbitrary number of strata. Recently, an explicit description of the summands involved in the decomposition theorem applied to such a variety has been obtained in a paper of…

Algebraic Geometry · Mathematics 2020-11-20 Francesca Cioffi , Davide Franco , Carmine Sessa

By applying a Gr\"{o}bner-Shirshov basis of the symmetric group $S_{n}$, we give two formulas for Schubert polynomials, either of which involves only nonnegative monomials. We also prove some combinatorial properties of Schubert…

Rings and Algebras · Mathematics 2017-09-15 Zerui Zhang , Yuqun Chen

The subgroup K=GL_p x GL_q of GL_{p+q} acts on the (complex) flag variety GL_{p+q}/B with finitely many orbits. We introduce a family of polynomials that specializes to representatives for cohomology classes of the orbit closures in the…

Representation Theory · Mathematics 2014-11-06 Benjamin J. Wyser , Alexander Yong

This chapter combines an introduction and research survey about Schubert varieties. The theme is to combinatorially classify their singularities using a family of polynomial ideals generated by determinants.

Algebraic Geometry · Mathematics 2023-03-03 Alexander Woo , Alexander Yong