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We classify all normal Schubert varieties in the affine Grassmannian of a semisimple group over an arbitrary field with special attention to small positive characteristic. The proof is elementary and relies on tangent space calculations for…

Algebraic Geometry · Mathematics 2025-07-10 Patrick Bieker , Timo Richarz

We show that smooth projective horospherical varieties with nef tangent bundles are rational homogeneous spaces.

Algebraic Geometry · Mathematics 2015-12-16 Qifeng Li

We collect here some known results on the subdifferential of one-homogeneous functionals, which are anisotropic and nonhomogeneous variants of the total variation and establish a new relationship between Lebesgue points of the calibrating…

Analysis of PDEs · Mathematics 2013-12-17 Antonin Chambolle , Michael Goldman , Matteo Novaga

To any connected and simply connected nilpotent Lie group N, one can associate its group of affine transformations Aff(N). In this paper, we study simply transitive actions of a given nilpotent Lie group G on another nilpotent Lie group N,…

Differential Geometry · Mathematics 2007-12-03 Dietrich Burde , Karel Dekimpe , Sandra Deschamps

We prove that affine invariant manifolds in strata of flat surfaces are algebraic varieties. The result is deduced from a generalization of a theorem of M\"oller. Namely, we prove that the image of a certain twisted Abel-Jacobi map lands in…

Dynamical Systems · Mathematics 2017-10-31 Simion Filip

Let $G$ be a connected reductive algebraic group. In this note we prove that for a quasi-affine $G$-spherical variety the weight monoid is determined by the weights of its non-trivial $\mathbb{G}_a$-actions that are homogeneous with respect…

Algebraic Geometry · Mathematics 2019-11-26 Andriy Regeta , Immanuel van Santen

Consider an equidimensional faithful conical action of an algebraic torus $T$ on an affine normal conical variety $X$ over an algebraically closed field of characteristic zero. Then there exists a finite normal subgroup $N$ of $T$ such that…

Group Theory · Mathematics 2017-07-19 Haruhisa Nakajima

We investigate some differential properties for permutations in the affine group, of a vector space V over the binary field, with respect to a new group operation $\circ$, inducing an alternative vector space structure on $V$ .

Group Theory · Mathematics 2016-01-18 Marco Calderini , Massimiliano Sala

In this paper we study (smooth and holomorphic) foliations which are invariant under transverse actions of Lie groups.

Geometric Topology · Mathematics 2010-12-15 Alexandre Behague , Bruno Scardua

We study holomorphic foliations with an affine homogeneous transverse structure. We give a friendly characterization of the case of transversely affine foliations in terms of matrix valued pairs of differential forms. This leads naturally…

Geometric Topology · Mathematics 2014-11-04 Bruno Scardua

We study a kind of modification of an affine domain which produces another affine domain. First appeared in passing in the basic paper of O. Zariski (1942), it was further considered by E.D. Davis (1967). The first named author applied its…

Algebraic Geometry · Mathematics 2007-05-23 Shulim Kaliman , Mikhail Zaidenberg

We prove a "Generic Equivalence Theorem which says that two affine morphisms $p: S \to Y$ and $q: T \to Y$ of varieties with isomorphic (closed) fibers become isomorphic under a dominant etale base change $\phi: U \to Y$. A special case is…

Representation Theory · Mathematics 2012-04-17 Hanspeter Kraft , Peter Russell

In this paper we prove a characterization of quotients of Abelian varieties by the actions of finite groups that are free in codimension-one via some vanishing conditions on the orbifold Chern classes. The characterization is given among a…

Algebraic Geometry · Mathematics 2016-10-18 Steven Lu , Behrouz Taji

Let X be an algebraic variety covered by open charts isomorphic to the affine space and q: X' \to X be the universal torsor over X. We prove that the automorphism group of the quasiaffine variety X' acts on X' infinitely transitively. Also…

Algebraic Geometry · Mathematics 2014-10-07 Ivan Arzhantsev , Alexander Perepechko , Hendrik Süß

In the last decades affine algebraic varieties and Stein manifolds with big (infinite-dimensional) automorphism groups have been intensively studied. Several notions expressing that the automorphisms group is big have been proposed. All of…

Complex Variables · Mathematics 2013-10-10 Frank Kutzschebauch

In this paper we consider some classical varieties of linear algebras over the field which has characteristic 0. For every considered variety we take a category of the finite generated free algebras of this variety. And for every this…

Rings and Algebras · Mathematics 2012-10-25 A. Tsurkov

We prove that every smooth subelliptic variety admits a surjective morphism from an affine space. This result gives partial answers to the questions of Arzhantsev and Forstneri\v{c}. As an application, we characterize open images of…

Algebraic Geometry · Mathematics 2022-12-14 Yuta Kusakabe

For an affine spherical homogeneous space G/H of a connected semisimple algebraic group G, we consider the factorization morphism by the action on G/H of a maximal unipotent subgroup of G. We prove that this morphism is equidimensional if…

Algebraic Geometry · Mathematics 2013-01-23 Roman Avdeev

We introduce the concept of the modularity of an abelian variety defined over the rational number field extending the modularity of an elliptic curve. We discuss the modularity of an abelian variety over the rational number field. We…

Number Theory · Mathematics 2026-01-30 Jae-Hyun Yang

We suggest the point of view that the Schubert classes of the affine Grassmannian of a simple algebraic group should be considered as Schur-positive symmetric functions. In particular, we give a geometric explanation of the Schur positivity…

Algebraic Geometry · Mathematics 2014-02-26 Thomas Lam