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We give an explicit combinatorial Chevalley-type formula for the equivariant K-theory of generalized flag varieties G/P which is a direct generalization of the classical Chevalley formula. Our formula implies a simple combinatorial model…

Representation Theory · Mathematics 2007-05-23 Cristian Lenart , Alexander Postnikov

We exhibit basic algebro-geometric results on the formal model of semi-infinite flag varieties and its Schubert varieties over an algebraically closed field $\mathbb K$ of characteristic $\neq 2$ from scratch. We show that the formal model…

Algebraic Geometry · Mathematics 2024-09-30 Syu Kato

We propose a refined but natural notion of toric degenerations that respect a given embedding and show that within this framework a Gorenstein Fano variety can only be degenerated to a Gorenstein Fano toric variety if it is embedded via its…

Algebraic Geometry · Mathematics 2020-11-26 Christian Steinert

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 g be a semi-simple Lie algebra. In this paper we study the spaces of based quasi-maps from the projective line P^1 to the flag variety of g (it is well-known that their singularities are supposed to model the singularities of the so…

Algebraic Geometry · Mathematics 2017-12-05 Alexander Braverman , Michael Finkelberg

Let $G$ be a simple, simply connected algebraic group over the field of complex numbers. We give a necessary and a sufficient condition for a Schubert variety $X(\tau)$ for which all the higher cohomologies $H^{i}(X(\tau), E)$ vanish for…

Algebraic Geometry · Mathematics 2013-03-04 S. Senthamarai Kannan

After proving that every Schubert variety in the full flag variety of a complex reductive group $G$ is a general Hessenberg variety, we show that not all such Schubert varieties are adjoint Hessenberg varieties. In fact, in types A and C,…

Algebraic Geometry · Mathematics 2021-07-19 Laura Escobar , Martha Precup , John Shareshian

Regular semisimple Hessenberg varieties are smooth subvarieties of the flag variety, and their examples contain the flag variety itself and the permutohedral variety which is a toric variety. We give a complete classification of Fano and…

Algebraic Geometry · Mathematics 2020-03-30 Hiraku Abe , Naoki Fujita , Haozhi Zeng

A Schubert variety in the complete flag manifold $GL_n/B$ is Levi-spherical if the action of a Borel subgroup in a Levi subgroup of a standard parabolic has a dense orbit. We give a combinatorial classification of these Schubert varieties.…

Combinatorics · Mathematics 2023-08-24 Yibo Gao , Reuven Hodges , Alexander Yong

We prove a criterion for the normality of Schubert varieties in twisted affine Grassmannians in terms of the order of the algebraic fundamental group of a certain Levi subgroup, in particular in small positive characteristic. As an…

Algebraic Geometry · Mathematics 2025-10-07 Patrick Bieker

We show that there is an affine Schubert variety in the infinite dimensional partial Flag variety (associated to the two- step parabolic subgroup of the Kac-Moody group {\hat SL(n)}, corresponding to omitting {\alpha}_0,{\alpha}_d) which is…

Algebraic Geometry · Mathematics 2015-05-04 V. Lakshmibai

The main result of this announcement is a formula for the tensor product of the class of a homogeneous line bundle with a Schubert class, expressed as a K(X)-linear combination of Schubert classes. We believe that this formula is the most…

Representation Theory · Mathematics 2007-05-23 Harsh Pittie , Arun Ram

We prove a conjecture of A. S. Buch concerning the structure constants of the Grothendieck ring of a flag variety with respect to its basis of Schubert structure sheaves. For this, we show that the coefficients in this basis of the…

Algebraic Geometry · Mathematics 2007-05-23 Michel Brion

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

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 paper, given a semisimple algebraic group $\bf G$ of rank 2, we construct a special semiorthogonal decomposition in the derived category of coherent sheaves on the flag variety ${\bf G}/{\bf B}$. These decompositions are defined…

Algebraic Geometry · Mathematics 2017-07-18 Alexander Samokhin

We propose a theory of double Schubert polynomials P_w(X,Y) for the Lie types B, C, D which naturally extends the family of Lascoux of Schutzenberger in type A. These polynomials satisfy positivity, orthogonality, and stability properties,…

Algebraic Geometry · Mathematics 2007-05-23 Andrew Kresch , Harry Tamvakis

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

Let $G$ be a simple algebraic group of adjoint type over the field $\mathbb{C}$ of complex numbers. Let $B$ be a Borel subgroup of $G$ containing a maximal torus $T$ of $G$. Let $w$ be an element of the Weyl group $W$ and let $X(w)$ be the…

Algebraic Geometry · Mathematics 2015-12-21 S. Senthamarai Kannan

We give a "lattice-theoretic" description of the global Schubert variety for $\mathrm{GL}_n$ associated to any dominant coweight.

Algebraic Geometry · Mathematics 2024-12-04 Pramod N. Achar , Andrea Bourque