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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

We describe the torus-equivariant cohomology of weighted partial flag orbifolds ${\mathrm{w}}\Sigma$ of type $A$. We establish counterparts of several results known for the partial flag variety that collectively constitute what we refer to…

Algebraic Topology · Mathematics 2019-06-14 Haniya Azam , Shaheen Nazir , Muhammad Imran Qureshi

Chern-Schwartz-MacPherson (CSM) classes generalize to singular and/or noncompact varieties the classical total homology Chern class of the tangent bundle of a smooth compact complex manifold. The theory of CSM classes has been extended to…

Algebraic Geometry · Mathematics 2025-04-02 Paolo Aluffi , Leonardo C. Mihalcea , Joerg Schuermann , Changjian Su

This survey paper describes two geometric representations of the permutation group using the tools of toric topology. These actions are extremely useful for computational problems in Schubert calculus. The (torus) equivariant cohomology of…

Algebraic Topology · Mathematics 2007-06-05 Julianna S. Tymoczko

We show that the Chern-Schwartz-MacPherson class of a hypersurface X in a nonsingular variety M `interpolates' between two other notions of characteristic classes for singular varieties, provided that the singular locus of X is smooth and…

Algebraic Geometry · Mathematics 2012-04-11 Paolo Aluffi , Jean-Paul Brasselet

The Chern-Schwartz-MacPherson class (CSM) and the Segre-Schwartz-MacPherson class (SSM) are deformations of the fundamental class of an algebraic variety. They encode finer enumerative invariants of the variety than its fundamental class.…

Algebraic Geometry · Mathematics 2018-10-03 L. M. Feher , R. Rimanyi

For a complex variety with a torus action we propose a new method of computing Chern-Schwartz-MacPherson classes. The method does not apply resolution of singularities. It is based on Localization Theorem in equivariant cohomology.

Algebraic Geometry · Mathematics 2012-06-07 Andrzej Weber

We define the equivariant Chern-Schwartz-MacPherson class of a possibly singular algebraic variety with a group action over the complex number field (or a field of characteristic 0). In fact, we construct a natural transformation from the…

Algebraic Geometry · Mathematics 2009-11-10 Toru Ohmoto

We consider the manifold $Fl_n(\mathbb{H})=Sp(n)/Sp(1)^n$ of all complete flags in $\mathbb{H}^n$, where $\mathbb{H}$ is the skew-field of quaternions. We study its equivariant $K$-theory rings with respect to the action of two groups:…

Algebraic Topology · Mathematics 2009-07-27 Augustin-Liviu Mare , Matthieu Willems

Let $G$ be a compact connected Lie group and $T$ be its maximal torus. The homogeneous space $G/T$ is called the (complete) flag manifold. One of the main goals of the {\em equivariant Schubert calculus} is to study the $T$-equivariant…

Algebraic Topology · Mathematics 2015-09-16 Shizuo Kaji

We give the formula for multiplying a Schubert class on an odd orthogonal or symplectic flag manifold by a special Schubert class pulled back from a Grassmannian of maximal isotropic subspaces. This is also the formula for multiplying a…

Combinatorics · Mathematics 2016-11-08 Nantel Bergeron , Frank Sottile

We discuss a relationship between Chern-Schwartz-MacPherson classes for Schubert cells in flag manifolds, Fomin-Kirillov algebra, and the generalized nil-Hecke algebra. We show that nonnegativity conjecture in Fomin-Kirillov algebra implies…

Combinatorics · Mathematics 2016-04-18 Seung Jin Lee

We consider the conormal bundle of a Schubert variety $S_I$ in the cotangent bundle $T^* Gr$ of the Grassmannian $Gr$ of $k$-planes in $C^n$. This conormal bundle has a fundamental class ${\kappa_I}$ in the equivariant cohomology…

Algebraic Geometry · Mathematics 2013-12-17 R. Rimanyi , V. Tarasov , A. Varchenko

The equivariant motivic Chern class of a Schubert cell in a `complete' flag manifold $X=G/B$ is an element in the equivariant K theory ring of $X$ to which one adjoins a formal parameter $y$. In this paper we prove several `folklore…

Algebraic Geometry · Mathematics 2025-04-02 Paolo Aluffi , Leonardo C. Mihalcea , Jörg Schürmann , Changjian Su

We describe the action of the Weyl group of a semi simple linear group $G$ on cohomological and K-theoretic invariants of the generalized flag variety $G/B$. We study the automorphism $s_i$, induced by the reflection in the simple root, on…

Algebraic Geometry · Mathematics 2024-05-28 Mieszko Baszczak

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

Let $G/P$ be a complex cominuscule flag manifold. We prove a type independent formula for the torus equivariant Mather class of a Schubert variety in $G/P$, and for a Schubert variety pulled back via the natural projection $G/Q \to G/P$. We…

Algebraic Geometry · Mathematics 2020-06-11 Leonardo C. Mihalcea , Rahul Singh

The main result of the paper is a Borel type description of the $Sp(1)^n$-equivariant cohomology ring of the manifold $Fl_n(\mathbb{H})$ of all complete flags in $\mathbb{H}^n$. To prove this, we obtain a Goresky-Kottwitz-MacPherson type…

Differential Geometry · Mathematics 2007-05-23 Augustin-Liviu Mare

We prove an explicit inverse Chevalley formula in the equivariant $K$-theory of semi-infinite flag manifolds of simply-laced type. By an inverse Chevalley formula, we mean a formula for the product of an equivariant scalar with a Schubert…

Representation Theory · Mathematics 2020-12-03 Takafumi Kouno , Satoshi Naito , Daniel Orr , Daisuke Sagaki

The Peterson variety is a subvariety of the flag manifold $G/B$ equipped with an action of a one-dimensional torus, and a torus invariant paving by affine cells, called Peterson cells. We prove that the equivariant pull-backs of Schubert…

Algebraic Geometry · Mathematics 2024-08-05 Rebecca Goldin , Leonardo Mihalcea , Rahul Singh
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