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We study the toric degeneration of Weyl group translated Schubert divisors of a partial flag variety of Lie type A via Gelfand-Cetlin polytopes. We propose a conjecture that Schubert varieties of appropriate dimensions intersect…

Algebraic Geometry · Mathematics 2021-12-24 DongSeon Hwang , Hwayoung Lee , Jae-Hyouk Lee , Changzheng Li

We consider tangent cones of Schubert varieties in the complete flag variety, and investigate the problem when the tangent cones of two different Schubert varieties coincide. We give a sufficient condition for such coincidence, and…

Representation Theory · Mathematics 2017-06-12 Dmitry Fuchs , Alexandre Kirillov , Sophie Morier-Genoud , Valentin Ovsienko

A permutation is called covexillary if it avoids the pattern $3412$. We construct an open embedding of a covexillary matrix Schubert variety into a Grassmannian Schubert variety. As applications of this embedding, we show that the…

Algebraic Geometry · Mathematics 2022-03-29 Rahul Singh

This article explores the relationship between Schubert varieties and equivariant embeddings, using the framework of homogeneous fiber bundles over flag varieties. We show that the homogenous fiber bundles obtained from…

Algebraic Geometry · Mathematics 2023-09-19 Mahir Bilen Can , Pinaki Saha

In this note, we give Gysin formulas for partial flag bundles for the classical groups. We then give Gysin formulas for Schubert varieties in Grassmann bundles, including isotropic ones. All these formulas are proved in a rather uniform way…

Algebraic Geometry · Mathematics 2018-02-27 Lionel Darondeau , Piotr Pragacz

Let G denote a complex, semisimple, simply-connected group. We identify the equivariant quantum differential equation for the cotangent bundle to the flag variety of G with the affine Knizhnik-Zamolodchikov connection of Cherednik and…

Algebraic Geometry · Mathematics 2010-09-07 Alexander Braverman , Davesh Maulik , Andrei Okounkov

A partial flag variety is a smooth projective homogeneous variety admitting an action of a maximal torus $T$. Schubert varieties are $T$-invariant subvarieties of the partial flag varieties. We study toric Schubert varieties in Grassmannian…

Algebraic Geometry · Mathematics 2024-01-15 Shin-young Kim , Eunjeong Lee

We compute the coherent cohomology of the structure sheaf of complex periplectic Grassmannians. In particular, we show that it can be decomposed as a tensor product of the singular cohomology ring of a Grassmannian for either the symplectic…

Algebraic Geometry · Mathematics 2024-12-31 Steven V Sam , Andrew Snowden

We present an explicit construction of tilting bundles on cotangent bundles of Grassmannians of 2-planes. This construction is based on Kapranov's exceptional collection for the underlying Grassmannians, and utilizes specific iterative…

Algebraic Geometry · Mathematics 2025-03-17 Wei Tseu

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

A Kazhdan-Lusztig variety is the intersection of a locally-closed Schubert cell with an opposite Schubert variety in a flag variety. We present a linear parametrization of the Schubert cells in the affine type A flag variety via…

Algebraic Geometry · Mathematics 2024-04-26 Balázs Elek , Daoji Huang

In this work we extend some previously known results on the automorphism group of Schubert varieties. We consider the Schubert conditions which define a Schubert variety. An automorphism of the Grassmannian fixes a Schubert variety…

Algebraic Geometry · Mathematics 2017-01-10 Fernando Piñero

The nilpotent cone of a reductive Lie algebra has a desingularization given by thecotangent bundle of the flag variety. Analogously, the nullcone of a cartesianpower of the algebra has a desingularization given by a vector bundle over…

Representation Theory · Mathematics 2016-04-25 Jean-Yves Charbonnel , Mouchira Zaiter

We prove that the prime torsion in the local integral intersection cohomology of Schubert varieties in the flag variety of the general linear group grows exponentially in the rank. The idea of the proof is to find a highly singular point in…

Algebraic Geometry · Mathematics 2015-12-29 Geordie Williamson

We prove that the affine closure of the cotangent bundle of the basic affine space of a complex semisimple group has conical symplectic singularities, which confirms a conjecture of Ginzburg and Kazhdan. We also show that this variety is…

Algebraic Geometry · Mathematics 2024-05-09 Tom Gannon

We study Schubert polynomials using geometry of infinite-dimensional flag varieties and degeneracy loci. Applications include Graham-positivity of coefficients appearing in equivariant coproduct formulas and expansions of back-stable and…

Algebraic Geometry · Mathematics 2025-02-19 David Anderson

In this paper, we study equivariant vector bundles on partial flag varieties arising from Schur functors. We show that a partial flag variety with three or more steps does not admit an Ulrich bundle of this form with respect to the minimal…

Algebraic Geometry · Mathematics 2015-12-23 Izzet Coskun , Jack Huizenga , Matthew Woolf

We extend the short presentation due to [Borel '53] of the cohomology ring of a generalized flag manifold to a relatively short presentation of the cohomology of any of its Schubert varieties. Our result is stated in a root-system uniform…

Combinatorics · Mathematics 2010-11-29 Victor Reiner , Alexander Woo , Alexander Yong

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

Quiver Grassmannians are projective varieties parametrizing subrepresentations of given dimension in a quiver representation. We define a class of quiver Grassmannians generalizing those which realize degenerate flag varieties. We show that…

Algebraic Geometry · Mathematics 2015-08-04 Giovanni Cerulli Irelli , Evgeny Feigin , Markus Reineke