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We give a new construction of the Bott-Samelson variety $Z$ as the closure of a $B$-orbit in a product of flag varieties $(G/B)^l$. This also gives an embedding of the projective coordinate ring of the variety into the function ring of a…

alg-geom · Mathematics 2008-02-03 Peter M. Magyar

Richardson varieties are obtained as intersections of Schubert and opposite Schubert varieties. We provide a new family of toric degenerations of Richardson varieties inside Grassmannians by studying Gr\"obner degenerations of their…

Commutative Algebra · Mathematics 2021-03-31 Narasimha Chary Bonala , Oliver Clarke , Fatemeh Mohammadi

We introduce the notion of a Seshadri stratification on an embedded projective variety. Such a structure enables us to construct a Newton-Okounkov simplicial complex and a flat degeneration of the projective variety into a union of toric…

Algebraic Geometry · Mathematics 2024-04-10 Rocco Chirivì , Xin Fang , Peter Littelmann

We obtain analogues of classical results on automorphism groups of holomorphic fiber bundles, in the setting of group schemes. Also, we establish a lifting property of the connected automorphism group, for torsors under abelian varieties.…

Algebraic Geometry · Mathematics 2011-06-30 Michel Brion

We determine which tangential varieties of homogeneously embedded rational homogeneous varieties are spherical. We determine the homogeneous coordinate rings and rings of covariants of the tangential varieties of homogenously embedded…

Algebraic Geometry · Mathematics 2007-05-23 J. M. Landsberg , Jerzy Weyman

The Hodge algebra structures on the homogeneous coordinate rings of Grassmann varieties provide semi-toric degenerations of these varieties. In this paper we construct these semi-toric degenerations using quasi-valuations and triangulations…

Algebraic Geometry · Mathematics 2018-04-12 Xin Fang , Peter Littelmann

In this paper we use formal group rings to construct an algebraic model of the $T$-equivariant oriented cohomology of smooth toric varieties. Then we compare our model with known results of equivariant cohomology of toric varieties to…

Algebraic Geometry · Mathematics 2015-03-27 Wanshun Wong

The Borel-Weil-Bott theorem describes the cohomology of line bundles over flag varieties. Here, one generalizes this theorem to a wider class of projective varieties : the wonderful varieties of minimal rank.

Algebraic Geometry · Mathematics 2007-05-23 Alexis Tchoudjem

We obtain two combinatorial results: an equality of Weyl groups and an inequality of roots, in the setting of generalised Bott-Samelson resolutions of minuscule Schubert varieties. These results are used in the companion paper [BK19] to…

Algebraic Geometry · Mathematics 2019-10-15 Michel Brion , S. Senthamarai Kannan

We propose a version of the Hodge conjecture in Bott-Chern cohomology and using results from characterizing real holomorphic chains by real rectifiable currents to provide a proof for this question. We define a Bott-Chern differential…

Complex Variables · Mathematics 2019-10-07 Jyh-Haur Teh , Chin-Jui Yang

We know that semi-regular sub-varieties satisfy the variational Hodge conjecture i.e., given a family of smooth projective varieties $\pi:\mathcal{X} \to B$, a special fiber $\mathcal{X}_o$ and a semi-regular subvariety $Z \subset…

Algebraic Geometry · Mathematics 2016-12-05 Ananyo Dan , Inder Kaur

The subject of this work is to study martingales in a reductive homogeneous space with respect to a symmetric connection. Our basic idea is to view homogenous spaces as principal fiber bundles and, thus, to study martingales on homogeneous…

Probability · Mathematics 2014-04-04 S. N. Stelmastchuk

We present a class of homogeneous ideals which are generated by monomials and binomials of degree two and are set-theoretic complete intersections. This class includes certain reducible varieties of minimal degree and, in particular, the…

Algebraic Geometry · Mathematics 2007-06-28 Margherita Barile

We analyze a class of spatial random spanning trees built on a realization of a homogeneous Poisson point process of the plane. This tree has a simple radial structure with the origin as its root. We first use stochastic geometry arguments…

Probability · Mathematics 2007-05-23 Francois Baccelli , Charles Bordenave

We consider all Bott-Samelson varieties ${\rm BS}(s)$ for a fixed connected semisimple complex algebraic group with maximal torus $T$ as the class of objects of some category. The class of morphisms of this category is an extension of the…

Representation Theory · Mathematics 2017-08-14 Vladimir Shchigolev

In view of the Segal construction each category with a coherent operation gives rise to a cohomology theory. Similarly each open stable differential relation $R$ imposed on smooth maps of manifolds determines cohomology theories $k^*$ and…

Geometric Topology · Mathematics 2018-01-18 Rustam Sadykov

In his Ph.D. thesis, Sean Griffin introduced a family of ideals and found monomial bases for their quotient rings. These rings simultaneously generalize the Delta Conjecture coinvariant rings of Haglund-Rhoades-Shimozono and the cohomology…

Combinatorics · Mathematics 2023-08-01 Tianyi Yu

In this paper, we study the geometry of $GT-$varieties $X_{d}$ with group a finite cyclic group $\Gamma \subset \mathrm{GL}(n+1,\mathbb{K})$ of order $d$. We prove that the homogeneous ideal $\mathrm{I}(X_{d})$ of $X_{d}$ is generated by…

Algebraic Geometry · Mathematics 2021-04-13 Liena Colarte-Gómez , Rosa M. Miró-Roig

A Bott manifold is a smooth projective toric variety having an iterated $\mathbb{C} P^1$-bundle structure. A certain family of Bott manifolds is used to understand the structure of Bott--Samelson varieties (or…

Algebraic Geometry · Mathematics 2025-11-13 Junho Jeong , Jang Soo Kim , Eunjeong Lee

Using the language of Seshadri stratifications we develop a geometrical interpretation of Lakshmibai-Seshadri-tableaux and their associated standard monomial bases. These tableaux are a generalization of Young-tableaux and…

Algebraic Geometry · Mathematics 2024-09-19 Henrik Müller