共查询到20条相似文献,搜索用时 9 毫秒
1.
Paolo Cascini 《Central European Journal of Mathematics》2006,4(2):209-224
For any smooth projective variety, we study a birational invariant, defined by Campana which depends on the Kodaira dimension
of the subsheaves of the cotangent bundle of the variety and its exterior powers.
We provide new bounds for a related invariant in any dimension and in particular we show that it is equal to the Kodaira dimension
of the variety, in dimension up to 4, if this is not negative. 相似文献
2.
I. A. Chel’tsov 《Mathematical Notes》2000,68(1):113-119
The objective of this paper is to study the birational structure of smooth hypersurfaces of degreeN in
by examining properties of moving log pairs on them.
Translated fromMatematicheskie Zametki, Vol. 68, No. 1, pp 131–138, July, 2000. 相似文献
3.
We study the notions of closed, open, initial and final morphism with respect to a closure operator and show that they have a perfectly symmetric pullback behaviour. We also investigate their interaction with closed and with open subobjects and the impact of the existence of suitably defined complements of subobjects. 相似文献
4.
Andrzej Weber 《Proceedings of the American Mathematical Society》1999,127(12):3513-3516
Let be a map of algebraic varieties. Barthel, Brasselet, Fieseler, Gabber and Kaup have shown that there exists a homomorphism of intersection homology groups compatible with the induced homomorphism on cohomology. The crucial point in the argument is reduction to the finite characteristic. We give an alternative and short proof of the existence of a homomorphism . Our construction is an easy application of the Decomposition Theorem.
5.
Torgunn Karoline Moe 《Mathematische Nachrichten》2015,288(1):76-88
In this article we give an upper bound for the number of cusps on a cuspidal curve on a Hirzebruch surface. We adapt the results that have been found for a similar question asked for cuspidal curves on the projective plane, and restate the results in this new setting. 相似文献
6.
Alexander Chubarev Iosif Pinelis 《Proceedings of the American Mathematical Society》1999,127(9):2735-2744
It is proved that any mapping of an -dimensional affine space over a division ring onto itself which maps every line into a line is semi-affine, if and . This result seems to be new even for the real affine spaces. Some further generalizations are also given. The paper is self-contained, modulo some basic terms and elementary facts concerning linear spaces and also - if the reader is interested in other than , , or - division rings.
7.
By computing the class of the universal antiramification locus of the Gauss map, we obtain a complete birational classification by Kodaira dimension of the universal theta divisor over the moduli space of curves. 相似文献
8.
For a d ×d expanding matrix A, we de.ne a pseudo‐norm w (x) in terms of A and use this pseudo‐norm (instead of the Euclidean norm) to define the Hausdorff measure and the Hausdorff dimension dimw H E for subsets E in R d . We show that this new approach gives convenient estimations to the classical Hausdorff dimension dimw H E, and in the case that the eigenvalues of A have the same modulus, then dimw H E and dimH E coincide. This setup is particularly useful to study self‐affine sets T generated by ?j (x) = A–1(x +dj), dj ∈ R d , j = 1, …, N. We use it to investigate the fractality of T for the case that {?j }N j =1 satisfying the open set condition as well as the cases without the open set condition. We extend some well‐known results in the self‐similar sets to the self‐af.ne sets. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
We study applications of divisibility properties of recurrence sequences to Tate’s theory of abelian varieties over finite
fields.
相似文献
10.
H.H. Hung 《Topology and its Applications》1982,14(2):163-165
We propose a generalization of Heath's theorem that semi-metric spaces with point-countable bases are developable: A semi-metrizable space X is developabale if (and only if) there is on it a σ-discrete family of closed sets, interior-preserving over each member C of which is a countable family {n(C): n ∈ N} of collections of open sets such that if U is a neighbourhood of ξ∈X, then there are such a Γ∈ and such a v∈ N that ξ ? Γ and ξ∈ int ∩ (D: ξ: D∈v(Γ))?U. 相似文献
11.
A new version and a modified proof of Yulmukhametov’s theorem on the decomposition of measures are given. Translated fromMatematicheskie Zametki, Vol. 67, No. 6, pp. 859–862, June, 2000. 相似文献
12.
José Carlos Sierra Andrea Luigi Tironi 《Proceedings of the American Mathematical Society》2007,135(5):1263-1269
We classify smooth complex projective varieties of dimension admitting a divisor of the form among their hyperplane sections, both and of codimension in their respective linear spans. In this setting, one of the following holds: 1) is either the Veronese surface in or its general projection to , 2) and is contained in a quadric cone of rank or , 3) and .
13.
Olaf Bröcker 《Journal of Geometry》1998,61(1-2):32-38
This note shows that a theorem of miquelian type known as (M2) holds in a certain non miquelian Laguerre plane of shear type as defined by Löwen and Pfüller[1].Dedicated to Professor H. Karzel on the occasion of his 70th birthday 相似文献
14.
Let K be a continuum in the plane which does not lie on a line. Then the set of differences, K - K, contains an open set. Let ψ be an automorphism of the field of complex numbers which is bounded on an Fσ set of positive inductive dimension. Then ψ is continuous. 相似文献
15.
Victor Pambuccian 《Geometriae Dedicata》2000,81(1-3):215-218
We provide definitions of and of noncollinearity by positive statements in terms of the ternary predicate of collinearity which are valid in affine n-dimensional geometry. This provides the intrinsic reason for the validity of V. Corbas's theorem stating that surjective maps between affine planes that preserve collinearity are isomorphisms, and of P. Maroscia's higher-dimensional generalization thereof. 相似文献
16.
This paper discusses a theorem in birational geometry that J.L. Coolidge attributed to Alfred Clebsch. The background is reconstructed from letters Felix Klein exchanged with Max Noether in 1894, when Noether was completing work on a lengthy report with Alexander Brill on the history of algebraic functions. Noether was deeply troubled to learn that Klein had informed him back in 1869 about relevant results that Clebsch and Leopold Kronecker had discussed in Berlin. These exchanges with Klein led to revisions in the Brill-Noether report, made in part to ensure Noether's own priority rights and larger intellectual legacy. 相似文献
17.
Cesare Donolato 《International Journal of Mathematical Education in Science & Technology》2017,48(8):1281-1284
The butterfly theorem is proved by assigning point masses to the four vertices of the wings and using the distributive property of the mass centre of a mechanical system. 相似文献
18.
V. V. Rane 《Proceedings Mathematical Sciences》1993,103(2):127-133
Following appropriate use of approximate functional equation for Hurwitz Zeta function, we obtain upper bounds for
} Here fors = σ + it, L(s,x) denotes DirichletL-series for character x(modq). In particular, we obtain S(1/2 +it) ≪q logqt + t5/8 q−1/8, which is an improvement in the range q |t| < q11/7, on hitherto best known result. This incidentally gives S(1/2+ it)≪ q log3q for |t|q9/5. 相似文献
19.
G. C. Bell A. N. Dranishnikov 《Transactions of the American Mathematical Society》2006,358(11):4749-4764
We prove an asymptotic analog of the classical Hurewicz theorem on mappings that lower dimension. This theorem allows us to find sharp upper bound estimates for the asymptotic dimension of groups acting on finite-dimensional metric spaces and allows us to prove a useful extension theorem for asymptotic dimension. As applications we find upper bound estimates for the asymptotic dimension of nilpotent and polycyclic groups in terms of their Hirsch length. We are also able to improve the known upper bounds on the asymptotic dimension of fundamental groups of complexes of groups, amalgamated free products and the hyperbolization of metric spaces possessing the Higson property.
20.
We present a short elementary proof of the following twelve-point theorem. Let M be a convex polygon with vertices at lattice points, containing a single lattice point in its interior. Denote by m (respectively, m*) the number of lattice points in the boundary of M (respectively, in the boundary of the dual polygon). Then m + m* = 12.Translated from Matematicheskie Zametki, vol. 77, no. 1, 2005, pp. 117–120.Original Russian Text Copyright © 2005 by D. Repov, M. Skopenkov, M. Cencelj.This revised version was published online in April 2005 with a corrected issue number. 相似文献