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We consider quotients of complete flag manifolds in Cn and Rn by an action of the symmetric group on n objects. We compute their cohomology with field coefficients of any characteristic. Specifically, we show that these topological spaces…

Algebraic Topology · Mathematics 2023-12-20 Lorenzo Guerra , Santanil Jana

It is well-known that the $T$-fixed points of a Schubert variety in the flag variety $GL_n(\mathbb{C})/B$ can be characterized purely combinatorially in terms of Bruhat order on the symmetric group $\mathfrak{S}_n$. In a recent preprint,…

Algebraic Geometry · Mathematics 2022-02-09 Megumi Harada , Martha Precup

We initiate the study of affine Deligne-Lusztig varieties with arbitrarily deep level structure for general reductive groups over local fields. We prove that for GLn and its inner forms, Lusztig's semi-infinite Deligne-Lusztig construction…

Algebraic Geometry · Mathematics 2021-01-06 Charlotte Chan , Alexander B. Ivanov

We generalize the classification of isomorphism classes of Schubert varieties in complete flag varieties G/B to a class of partial flag varieties G/P. In particular, we classify all Schubert varieties in G/P where P is a minimal parabolic…

Combinatorics · Mathematics 2025-11-25 Yanjun Chen

We prove a boundedness-theorem for families of abelian varieties with real multiplication. More generally, we study curves in Hilbert modular varieties from the point of view of the Green Griffiths-Lang conjecture claiming that entire…

Algebraic Geometry · Mathematics 2018-10-01 Erwan Rousseau , Frédéric Touzet

We initiate the representation theory of the degenerate affine periplectic Brauer algebra on $n$ strands by constructing its finite-dimensional calibrated representations when $n=2$. We show that any such representation that is…

Representation Theory · Mathematics 2019-05-14 Zajj Daugherty , Iva Halacheva , Mee Seong Im , Emily Norton

We study the existence of invariant Einstein metrics on real flag manifolds associated to simple and non-compact split real forms of complex classical Lie algebras whose isotropy representation decomposes into two or three irreducible…

Differential Geometry · Mathematics 2020-07-06 Brian Grajales , Lino Grama

In this paper we study the geometric structure of affine Deligne-Lusztig varieties for $GL_n$ and $b$ basic. We introduce a new condition on $\lambda$. If this is satisfied, then the corresponding affine Deligne-Lusztig variety is the…

Algebraic Geometry · Mathematics 2022-04-25 Ryosuke Shimada

We study Hilbert-Samuel multiplicity for points of Schubert varieties in the complete flag variety, by Groebner degenerations of the Kazhdan-Lusztig ideal. In the covexillary case, we give a positive combinatorial rule for multiplicity by…

Algebraic Geometry · Mathematics 2011-11-08 Li Li , Alexander Yong

We study algebraic geometry linear codes defined by linear sections of the Grassmannian variety as codes associated to FFN$(1,q)$-projective varieties. As a consequence, we show that Schubert, Lagrangian-Grassmannian, and isotropic…

Algebraic Geometry · Mathematics 2016-06-02 Jesús Carrillo-Pacheco , Felipe Zaldívar

We compute the Hilbert series of general weighted flag varieties and discuss a computer-aided method to determine their defining equations. We apply our results to weighted flag varieties coming from the Lie groups of type G_2 and GL(6), to…

Algebraic Geometry · Mathematics 2014-02-26 Muhammad Imran Qureshi , Balazs Szendroi

We give the construction of weighted Lagranngiann Grassmannians$wLGr(3,6)$ and weighted partial $A_3$ flag variety $wFl_{1,3}$ coming from the symplectic Lie group $Sp(6,\mathbb C)$ and the general linear group $GL(4,\mathbb C)$…

Algebraic Geometry · Mathematics 2019-02-20 Muhammad Imran Qureshi

The paper computes the Witt-sheaf cohomology rings of partial flag varieties in type A in terms of the Pontryagin classes of the subquotient bundles. The proof is based on a Leray-Hirsch-type theorem for Witt-sheaf cohomology for the…

Algebraic Geometry · Mathematics 2024-11-18 Thomas Hudson , Ákos K. Matszangosz , Matthias Wendt

We construct the homogeneous Einstein equation for generalized flag manifolds $G/K$ of a compact simple Lie group $G$ whose isotropy representation decomposes into five inequivalent irreducible $\Ad(K)$-submodules. To this end we apply a…

Differential Geometry · Mathematics 2019-11-25 Andreas Arvanitoyeorgos , Ioannis Chrysikos , Yusuke Sakane

We aim in this manuscript to describe a specific notion of geometric positivity that manifests in cohomology rings associated to the flag variety $G/B$ and, in some cases, to subvarieties of $G/B$. We offer an exposition on the the…

Algebraic Geometry · Mathematics 2023-06-27 Rebecca Goldin

We construct the first aperiodic tiles for two amenable 3-dimensional Lie groups: Sol and the Heisenberg group. Our construction relies on the use of higher-dimensional uniformly finite homology. In particular, we settle completely the…

Group Theory · Mathematics 2012-05-17 Piotr W. Nowak , Shmuel Weinberger

Let G be a connected semisimple complex algebraic group and let P be a parabolic subgroup. In this paper we define a new (commutative and associative) product on the cohomology of the homogenous spaces G/P and use this to give a more…

Algebraic Geometry · Mathematics 2016-09-07 Prakash Belkale , Shrawan Kumar

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

Although regular semisimple Hessenberg varieties are smooth and irreducible, semisimple Hessenberg varieties are not necessarily smooth in general. In this paper we determine the irreducible components of semisimple Hessenberg varieties…

Algebraic Geometry · Mathematics 2017-09-19 Erik Insko , Martha Precup

Complex geometric properties of the orbits of a non-compact real form $G_0$ in a flag manifold $Z=G/Q$ of a complex semi-simple groups $G=G_0^\mathbb C$ are studied. Schubert varieties are used to construct a complex submanifold with…

Algebraic Geometry · Mathematics 2007-05-23 A. Huckleberry , J. A. Wolf