共查询到20条相似文献,搜索用时 31 毫秒
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We study the behaviour of the notion of ``sub-adjoint ideal to a projective variety" with respect to general hyperplane sections. As an application we show that the two classical definitions of sub-adjoint hypersurface given respectively by Enriques and Zariski are equivalent.
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M. C. Beltrametti A. Lanteri A. J. Sommese 《Rendiconti del Circolo Matematico di Palermo》2014,63(2):247-255
Let \((X,L)\) be a smooth polarized variety of dimension \(n\) . Let \(A\in |L|\) be an irreducible hypersurface and let \(\Sigma \) be the singular locus of \(A\) . We assume that \(\Sigma \) is a smooth subvariety of dimension \(k\ge 2\) , and odd codimension \(\ge 3\) . Motivated from the results of Beltrametti et al. (J. Math. Soc. Jpn. 2014), we study the nefness and bigness of the adjoint bundle \(K_{\Sigma }+ (k-2)L_{\Sigma }\) in this framework. Several explicit examples show that the results are effective. 相似文献
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Vladimir D. Tonchev 《Geometriae Dedicata》1993,48(3):295-308
It is proved that a quasi-symmetric design with theSymmetric Difference Property (SDP) is uniquely embeddable as a derived or a residual design into a symmetric SDP design. Alternatively, any quasi-symmetric SDP design is characterized as the design formed by the minimum weight vectors in a binary code spanned by the simplex code and the incidence vector of a point set in PG(2m-1, 2) that intersects every hyperplane in one of two prescribed numbers of points. Applications of these results for the classification of point sets in PG(2m-1, 2) with the same intersection properties as an elliptic or a hyperbolic quadric, as well as the classification of codes achieving the Grey-Rankin bound are discussed. 相似文献
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Baku. Translated from Sibirskii Matematicheskii Zhurnal, Vol. 33, No. 3, pp. 131–145, May–June, 1992. 相似文献
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In this article, we prove a comparison theorem between the Dwork cohomology introduced by Adolphson and Sperber and the rigid cohomology. As a corollary, we can calculate the rigid cohomology of Dwork isocrystal on torus. 相似文献
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Ricardo García López 《manuscripta mathematica》1998,97(1):45-58
We give upper bounds for the absolute value of exponential sums in several variables attached to certain polynomials with
coefficients in a finite field. This bounds are given in terms of invariants of the singularities of the projective hypersurface
defined by its highest degree form. For exponential sums attached to the reduction modulo a power of a large prime of a polynomial
f with integer coefficients and veryfying a certain condition on the singularities of its highest degree form, we give a bound
in terms of the dimension of the Jacobian quotient .
Received: 3 November 1997 相似文献
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Let F denote a finite field with q=pf elements, and let σ(A) equal the trace of the square matrix A. This paper evaluates exponential sums of the form S(E,X1,…,Xn)e{?σ(CX1?XnE)}, where S(E,X1,…,Xn) denotes a summation over all matrices E,X1,…,Xn of appropriate sizes over F, and C is a fixed matrix. This evaluation is then applied to the problem of counting ranked solutions to matrix equations of the form U1?UαA+DV1?Vβ=B where A,B,D are fixed matrices over F. 相似文献
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Jawad Snoussi 《Bulletin of the Brazilian Mathematical Society》2005,36(3):309-317
We prove that the planar components of the tangent cone of a complex analytic surface at a point correspond to the base points
of hyperplane sections by the Nash modification. This correspondence is then used to characterize domination relations between
the normalized Nash modification and the normalized blow-up of a point. 相似文献
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We study approximation of some well-known network design problems such as the traveling salesman problem (for both minimization and maximization versions) and the min steiner tree problem by moderately exponential algorithms. The general goal of the issue of moderately exponential approximation is to catch up on polynomial inapproximability by designing superpolynomial algorithms achieving approximation ratios unachievable in polynomial time. Worst-case running times of such algorithms are significantly smaller than those needed for optimal solutions of the problems handled. 相似文献
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Régis Blache 《Journal of Number Theory》2004,105(2):361-386
We give bounds for exponential sums associated to functions on curves defined over Galois rings. We first define summation subsets as the images of lifts of points from affine opens of the reduced curve, and give bounds for the degrees of their coordinate functions. Then we get bounds for exponential sums, extending results of Kumar et al., Winnie Li over the projective line, and Voloch-Walker over elliptic curves and Cab curves. 相似文献
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Á. Pintér 《Journal of Number Theory》2009,129(7):1664-1668
Using some results from the modern theory of diophantine equations we prove that the numbers of cells in simple arrangements of hyperplanes in Rm and Rn (m and n are different positive integers with m,n?2) are finitely many times equal. 相似文献
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Paul A. Catlin 《Journal of Number Theory》1976,8(3):282-288
There is no known necessary and sufficient condition on a sequence {αn} of nonnegative real numbers such that for almost all x (in the sense of Lebesgue measure) there are infinitely many fractions satisfying . Nor is any condition known when is required to be reduced. We shall consider the relation of these problems to each other, and we shall discuss conjectured answers for these questions. 相似文献
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A. I. Barvinok 《Functional Analysis and Its Applications》1992,26(2):127-129
Sechenov Institute of Evolutional Physiology and Biochemistry of RAN. Translated from Funktsional'nyi Analiz i Ego Prilozheniya, Vol. 26, No. 2, pp. 64–66, April–June, 1992. 相似文献