共查询到20条相似文献,搜索用时 31 毫秒
1.
Ernesto C. Mistretta 《Mathematische Nachrichten》2020,293(11):2175-2186
A generically generated vector bundle on a smooth projective variety yields a rational map to a Grassmannian, called Kodaira map. We answer a previous question, raised by the asymptotic behaviour of such maps, giving rise to a birational characterization of abelian varieties. In particular we prove that, under the conjectures of the Minimal Model Program, a smooth projective variety is birational to an abelian variety if and only if it has Kodaira dimension 0 and some symmetric power of its cotangent sheaf is generically generated by its global sections. 相似文献
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《Journal of Pure and Applied Algebra》2022,226(6):106969
We investigate the secant dimensions and the identifiability of flag varieties parametrizing flags of subspaces of a fixed vector space. We give numerical conditions ensuring that secant varieties of flag varieties have the expected dimension, and that a general point on these secant varieties is identifiable. 相似文献
4.
Inspired by recent work of Cerulli, Feigin and Reineke on desingularizations of quiver Grassmannians of representations of Dynkin quivers, we obtain desingularizations in considerably more general situations and in particular for Grassmannians of modules over iterated tilted algebras of Dynkin type. Our desingularization map is constructed from Nakajima's desingularization map for graded quiver varieties. 相似文献
5.
Ming Li 《Calculus of Variations and Partial Differential Equations》1995,3(4):513-529
In this paper, we study energy minimizing harmonic maps into a complete Riemannian manifold. We prove that the singular set of such a map has Hausdorff dimension at mostn–2, wheren is the dimension of the domain. We will also give an example of an energy minimizing map from surface to surface that has a singular point. Thus then–2 dimension estimate is optimal, in contrast to then–3 dimension estimate of Schoen-Uhlenbeck [SU] for compact targets. 相似文献
6.
In this paper we give the full classification of surfaces X such that the family of lines contained in a (k+1)-secant
to X has dimension smaller than the expected. 相似文献
7.
Benjamin Nill 《Mathematische Zeitschrift》2006,252(4):767-786
We give equivalent and sufficient criteria for the automorphism group of a complete toric variety, respectively a Gorenstein
toric Fano variety, to be reductive. In particular we show that the automorphism group of a Gorenstein toric Fano variety
is reductive, if the barycenter of the associated reflexive polytope is zero. Furthermore a sharp bound on the dimension of
the reductive automorphism group of a complete toric variety is proven by studying the set of Demazure roots. 相似文献
8.
M. Brion 《Commentarii Mathematici Helvetici》2001,76(2):263-299
Let be the flag variety of a complex semi-simple group G, let H be an algebraic subgroup of G acting on with finitely many orbits, and let V be an H-orbit closure in . Expanding the cohomology class of V in the basis of Schubert classes defines a union V0 of Schubert varieties in with positive multiplicities. If G is simply-laced, we show that these multiplicities are equal to the same power of 2. For
arbitrary G, we show that V0 is connected in codimension 1. If moreover all multiplicities are 1, we show that the singularities of V are rational and
we construct a flat degeneration of V to V0 in . Thus, for any effective line bundle L on , the restriction map is surjective, and for all .
Received: April 17, 2000 相似文献
9.
J. M. Landsberg 《Journal of the American Mathematical Society》2006,19(2):447-459
We prove that the bilinear map corresponding to matrix multiplication of matrices is not the limit of a sequence of bilinear maps that can be executed by performing six multiplications. This solves a longstanding problem dating back to Strassen's discovery in 1968 that the map could be executed by performing seven multiplications.
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Baisheng Yan 《Calculus of Variations and Partial Differential Equations》2001,13(3):295-310
Given a number a weakly L-quasiregular map on a domain in space is a map u in a Sobolev space that satisfies almost everywhere in In this paper, we study the problem concerning linear boundary values of weakly L-quasiregular mappings in space with dimension It turns out this problem depends on the power p of the underlying Sobolev space. For p not too far below the dimension n we show that a weakly quasiregular map in can only assume a quasiregular linear boundary value; however, for all and , we prove a rather surprising existence result that every linear map can be the boundary value of a weakly L-quasiregular map in
Received July 20, 2000 / Accepted September 22, 2000 / Published online December 8, 2000 相似文献
12.
We prove birational boundedness results on complete intersections with trivial canonical class of base point free divisors in (some version of) Fano varieties. Our results imply in particular that Batyrev–Borisov toric construction produces only a bounded set of Hodge numbers in any given dimension, even as the codimension is allowed to grow. 相似文献
13.
We study geometric and statistical properties of complex rational maps satisfying a non-uniform hyperbolicity condition called “Topological Collet-Eckmann”. This condition is weaker than the “Collet-Eckmann” condition. We show that every such map possesses a unique conformal probability measure of minimal exponent, and that this measure is non-atomic, ergodic, and that its Hausdorff dimension is equal to the Hausdorff dimension of the Julia set. Furthermore, we show that there is a unique invariant probability measure that is absolutely continuous with respect to this conformal measure, and that this invariant measure is exponentially mixing (it has exponential decay of correlations) and satisfies the Central Limit Theorem.We also show that for a complex rational map the existence of such invariant measure characterizes the Topological Collet-Eckmann condition: a rational map satisfies the Topological Collet-Eckmann condition if, and only if, it possesses an exponentially mixing invariant measure that is absolutely continuous with respect to some conformal measure, and whose topological support contains at least 2 points. 相似文献
14.
Eduard Looijenga 《Inventiones Mathematicae》2009,177(1):213-233
The period map for cubic fourfolds takes values in a locally symmetric variety of orthogonal type of dimension 20. We determine
the image of this period map (thus confirming a conjecture of Hassett) and give at the same time a new proof of the theorem
of Voisin that asserts that this period map is an open embedding. An algebraic version of our main result is an identification
of the algebra of SL (6,ℂ)-invariant polynomials on the representation space Sym 3(ℂ6)* with a certain algebra of meromorphic automorphic forms on a symmetric domain of orthogonal type of dimension 20. We also
describe the stratification of the moduli space of semistable cubic fourfolds in terms of a Vinberg-Dynkin diagram. 相似文献
15.
Charles Ching-An Cheng 《Proceedings of the American Mathematical Society》2001,129(10):2819-2822
In this paper it is proved that a power linear Keller map of dimension three over a field of characteristic zero is linearly triangularizable.
16.
Arthur C. Bartels 《K-Theory》2003,28(1):19-37
We prove that the Assembly map in algebraic K-theory is split injective for groups of finite asymptotic dimension admitting a finite classifying space. 相似文献
17.
Akira Koyama 《Topology and its Applications》1984,17(3):247-255
This paper studies properties of refinable maps and contains applications to dimension theory. It is proved that refinable maps between compact Hausdorff spaces preserve covering dimension exactly and do not raise small cohomological dimension with any coefficient group. The notion of a c-refinable map is introduced and is shown to play a comparable role in the setting of normal spaces. For example, c-refinable maps between normal spaces are shown to preserve covering dimension and S-weak infinite-dimensionality. These facts do not hold for refinable maps. 相似文献
18.
Jerzy Jezierski 《Mathematische Annalen》2001,321(1):107-130
We prove that a self map of a PL-manifold of dimension is homotopic to a map with no periodic points of period n iff the Nielsen numbers (k divides n) disappear.
Received: 15 December 1999 / Accepted: 25 September 2000 / Published online: 18 June 2001 相似文献
19.
We first prove that any birational map, from an affine space of dimension ≥ 2 to itself, is not determined by its face functions.
On the other hand, we prove that a birational map with irreducibly polynomial inverse is completely determined, within the
class of all birational maps with irreducibly polynomial inverses, by its face functions. We show also how to effectively
reconstruct such a map from its face functions.
Supported partly by the Centre Interuniversitaireen Calcul Mathématique Algébrique. 相似文献
20.
We find all the arithmetically Gorenstein divisors on Fano varieties of dimension n and index r with 3 ≤ n ≤ 2r − 1 and ρ(Y) ≥ 2, where Y is smooth, connected, subcanonical and linearly normal.
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