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Let G denote a connected reductive algebraic group over an algebraically closed field k and let X denote a projective G x G-equivariant embedding of G. The large Schubert varieties in X are the closures of the double cosets BgB, where B…

Algebraic Geometry · Mathematics 2007-05-23 Michel Brion , Jesper Funch Thomsen

A Schubert class is called rigid if it can only be represented by Schubert varieties. The rigid Schubert classes have been classified in Grassmannians and orthogonal Grassmannians. In this paper, we study the rigidity problem in partial…

Algebraic Geometry · Mathematics 2024-10-30 Yuxiang Liu , Artan Sheshmani , Shing-Tung Yau

Let U be the tautological subbundle on the Grassmannian $\mathrm{Gr}(k, n)$. There is a natural morphism $\mathrm{Tot}(U) \to \mathbb{A}^n$. Using it, we give a semiorthogonal decomposition for the bounded derived category…

Algebraic Geometry · Mathematics 2018-07-06 Dmitrii Pirozhkov

Extending the main result of Part 1, in the first part of this paper we show that every quiver Grassmannian of a representation of a quiver of extended Dynkin type $D$ has a decomposition into affine spaces. In the case of real root…

Representation Theory · Mathematics 2017-09-18 Oliver Lorscheid , Thorsten Weist

Problem: Given a reductive algebraic group G, find all k-tuples of parabolic subgroups (P_1,...,P_k) such that the product of flag varieties G/P_1 x ... x G/P_k has finitely many orbits under the diagonal action of G. In this case we call…

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

We present a combinatorial and computational commutative algebra methodology for studying singularities of Schubert varieties of flag manifolds. We define the combinatorial notion of *interval pattern avoidance*. For "reasonable" invariants…

Algebraic Geometry · Mathematics 2008-09-13 Alexander Woo , Alexander Yong

We examine the orbits of the (complex) symplectic group, $Sp_n$, on the flag manifold, $\mathscr{F}\ell(\mathbb{C}^{2n})$, in a very concrete way. We use two approaches: we Gr\"obner degenerate the orbits to unions of Schubert varieties…

Algebraic Geometry · Mathematics 2014-11-11 Anna Bertiger

Secant varieties of a homogeneously embedded generalised Grassmannian $G/P$ inherit the natural group action, and one can reduce the study of their local geometric properties to $G$-orbit representatives. The case of secant varieties of…

Algebraic Geometry · Mathematics 2025-01-17 Vincenzo Galgano

The Schubert bases of the torus-equivariant homology and cohomology rings of the affine Grassmannian of the special linear group are realized by new families of symmetric functions called k-double Schur functions and affine double Schur…

Combinatorics · Mathematics 2011-05-12 Thomas Lam , Mark Shimozono

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

The aim of this paper is to construct certain closed embeddings of Grassmannian varieties, using tensor operations on vector bundles. These embeddings generalize Segre and Pl\"ucker morphisms.

Algebraic Geometry · Mathematics 2019-10-22 Mohammad Hadi Hedayatzadeh

In this paper the K-Theory and the category of homogeneous vector bundles on the symplectic Grassmannian SpGr(2,N) of isotropic 2-planes are discussed.

Algebraic Geometry · Mathematics 2012-06-28 Martina Bode

We study the local and global intersection cohomology of the intersection of two Schubert varieties in a flag manifold. In this version some new references are added.

Algebraic Geometry · Mathematics 2023-07-25 M. Dyer , G. Lusztig

This article concerns the study of a new invariant bilinear form $\mathcal B$ on the space of automorphic forms of a split reductive group $G$ over a function field. We define $\mathcal B$ using the asymptotics maps from…

Number Theory · Mathematics 2018-11-14 Jonathan Wang

Let $G$ be a complex quasi-simple algebraic group and $G/P$ be a partial flag variety. The projections of Richardson varieties from the full flag variety form a stratification of $G/P$. We show that the closure partial order of projected…

Algebraic Geometry · Mathematics 2015-02-10 Xuhua He , Thomas Lam

For each infinite series of the classical Lie groups of type B,C or D, we introduce a family of polynomials parametrized by the elements of the corresponding Weyl group of infinite rank. These polynomials represent the Schubert classes in…

Combinatorics · Mathematics 2022-04-05 Takeshi Ikeda , Leonardo C. Mihalcea , Hiroshi Naruse

Let $Q$ be a quiver, $M$ a representation of $Q$ with an ordered basis $\cB$ and $\ue$ a dimension vector for $Q$. In this note we extend the methods of \cite{L12} to establish Schubert decompositions of quiver Grassmannians $\Gr_\ue(M)$…

Representation Theory · Mathematics 2016-01-20 Oliver Lorscheid

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

Let $ G $ be a connected reductive algebraic group and its symmetric subgroup $ K $. The variety $ \dblFV = K/Q \times G/P $ is called a double flag variety, where $ Q $ and $ P $ are parabolic subgroups of $ K $ and $ G $ respectively. In…

Representation Theory · Mathematics 2024-07-16 Lucas Fresse , Kyo Nishiyama

Regular semisimple Hessenberg varieties are a family of subvarieties of the flag variety that arise in number theory, numerical analysis, representation theory, algebraic geometry, and combinatorics. We give a "Giambelli formula" expressing…

Algebraic Geometry · Mathematics 2011-08-31 Dave Anderson , Julianna Tymoczko