共查询到20条相似文献,搜索用时 31 毫秒
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Jörg M. Wills 《Mathematische Semesterberichte》2003,50(1):95-109
Zusammenfassung. Dieser Überblick skizziert Theorie und Anwendungen von Kugelpackungen, ausgehend von den klassischen Problemen von Kepler und Newton. Der weitaus wichtigste Bereich der regelmäßigen, gitterförmigen Kugelpackungen einschließlich der Anwendungen auf Codes wird kurz gehalten, weil es dazu ausgiebig Literatur gibt. Dagegen wird ausführlicher auf die in den letzten Jahren stark entwickelten endlichen Kugelpackungen eingegangen, die gute Modelle für die in der Nanotechnik wichtigen Microcluster sind. In jeder der relativ knapp gehaltenen Sektionen wird das zum Verständnis Unerlässliche an Theorie angegeben, sowie mindestens ein überraschendes oder im Wortsinn merkwürdiges Phänomen. Außerdem wird auf weiterführende Literatur verwiesen. Für Einsteiger sei insbesondere M. Leppmeiers Buch [L] empfohlen. 相似文献
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V. A. Zorich 《Moscow University Mathematics Bulletin》2016,71(3):102-105
The relationship of multidimensional geometry with statistical thermodynamics and with laws of large numbers is described. 相似文献
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O. Chein E. G. Goodaire 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2005,75(1):245-255
In [5, 6], the second author and D. A. ROBINSON initiated a study of non-Moufang Bol loops with the property that over a field,
necessarily of characteristic 2, their loop rings satisfy the right, but not the left, Bol identity. They called such loops
SRAR and showed that the family of SRAR loops includes those Bol loops which have a unique non-identity commutator/associator.
In [4, 2], the current authors presented a construction for a new class of Bol loops denoted L(B,m,n,r,s,t,z,w) with initial
data a given (possibly associative) Bol loop B, elements, r, s, t, z and w in the centre of B, and integers m and n. 相似文献
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Harvey W. Becher 《Historia Mathematica》1980,7(4):389-400
In a recent article, J. M. Dubbey [Historia Mathematica 4 (1977), 295–302] showed that George Peacock's A Treatise on Algebra (1830) was similar to an unpublished work written by Charles Babbage in 1821. Evidently perplexed about the absence of a dispute over priority, Dubbey concluded that Peacock had unconsciously assimilated Babbage's ideas, and that Babbage was too busy with other activities to be concerned. The thesis of this article is that the innovative aspects of the work of both Babbage and Peacock are extensions of ideas put forth in 1803 by Robert Woodhouse, and that probably neither Babbage nor Peacock was overly concerned with acknowledgments because their approach to algebra was not unique at Cambridge. 相似文献
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The new variable-step, variable-order, ODE solver, HBT(p) of order p, presented in this paper, combines a three-stage Runge-Kutta method of order 3 with a Taylor series method of order p-2 to solve initial value problems , where y:R→Rd and f:R×Rd→Rd. The order conditions satisfied by HBT(p) are formulated and they lead to Vandermonde-type linear algebraic systems whose solutions are the coefficients in the formulae for HBT(p). A detailed formulation of variable-step HBT(p) in both fixed-order and variable-order modes is presented. The new method and the Taylor series method have similar regions of absolute stability. To obtain high-accuracy results at high order, this method has been implemented in multiple precision. 相似文献
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采用CSSCI数据库中收录的全部期刊数据,通过相关分析、区间数据主成分分析等方法建立模型,客观地对整个数据库中期刊的整体特征进行全面、系统的分析,探寻其中的特征、规律以及原因,提出了办好学术期刊的一些方式方法. 相似文献
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Alex Bonutti Fabio De Cesco Luca Di Gaspero Andrea Schaerf 《Annals of Operations Research》2012,194(1):59-70
We propose a set of formulations for the Curriculum-Based Course Timetabling problem, with the aim of “capturing” many real-world
formulations, and thus encouraging researchers to “reduce” their specific problems to one of them, gaining the opportunity
to compare and assess their results. This work is accompanied by a web application that maintains all the necessary infrastructures for benchmarking: validators, data formats, instances, reference scores, lower bounds, solutions, and visualizers. All instances
proposed here are based on real data from various universities and they represent a variety of possible situations. 相似文献
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Résumé. La dynamique oscillante d'un champ de vecteurs analytique en dimension trois s'organise autour d'un nombre fini d'axes de
tourbillonnement lorsqu'elle ne se délocalise pas par des éclatements de point.
Received: December 12, 1998 相似文献
Oscillation, spiralement, tourbillonnement
Received: December 12, 1998 相似文献
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Let X
1,..., Xn be independent random variables such that {Xj 1}=1 and E
X
j=0 for all j. We prove an upper bound for the tail probabilities of the sum M
n=X1+...+ Xn. Namely, we prove the inequality {M
nx} 3.7 {Sn x}, where S
n=1+...+ n is a sum of centered independent identically distributed Bernoulli random variables such that E
S
n
2
=ME
M
n
2
and {k=1}=E
S
n
2
/(n+E
S
n
2
) for all k (we call a random variable Bernoulli if it assumes at most two values). The inequality holds for x at which the survival function x{S
nx} has a jump down. For remaining x, the inequality still holds provided that we interpolate the function between the adjacent jump points linearly or log-linearly. If necessary, in order to estimate {S
nx} one can use special bounds for binomial probabilities. Up to the factor at most 2.375, the inequality is final. The inequality improves the classical Bernstein, Prokhorov, Bennett, Hoeffding, Talagrand, and other bounds. 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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We shall present here results concerning the metric entropy of
spaces of linear and nonlinear approximation under very general conditions. Our
first result computes the metric entropy of the linear and m-terms
approximation classes according to a quasi-greedy basis verifying the
Temlyakov property. This theorem shows that the second index r is not visible
throughout the behavior of the metric entropy. However, metric entropy does
discriminate between linear and nonlinear approximation.
Our second result extends and refines a result
obtained in a Hilbertian framework by Donoho, proving that under orthosymmetry
conditions, m-terms approximation classes are characterized by the metric
entropy. Since these theorems are given under the general context of quasi-greedy
bases verifying the Temlyakov property, they have a large spectrum of
applications. For instance, it is proved in the last section that they can be
applied in the case of
L
p
norms for
R
d
for 1 < p < \infty.
We show that the lower bounds needed for this paper in fact follow
from quite simple
large deviation inequalities concerning hypergeometric or binomial distributions.
To prove the upper bounds, we provide a very simple universal coding
based on a thresholding-quantizing constructive procedure. 相似文献
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利用半群的理想和双理想呈现的包含关系定义了新的半群类B0,I0,B1,I1,C0-半群,讨论其性质,证明了正则半群S是C0-半群的充要条件是S是矩形带;B0,I0,B1,I1,C0-半群各自的直积半群和关于同余的商半群保持B0,I0,B1,I1,C0性. 相似文献
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Automorphisms of distance-regular graphs are considered. It is proved that any graph with the intersection array {60, 45, 8; 1, 12, 50} is not vertex symmetric, and any graph with the intersection array {49, 36, 8; 1, 6, 42} is not edge symmetric. 相似文献
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We prove that the arrays {52, 35, 16; 1, 4, 28} and {69, 48, 24; 1, 4, 46} cannot be realized as the intersection arrays of distance-regular graphs. In the proof we use some inequalities bounding the size of substructures (cliques, cocliques) in a distance-regular graph. 相似文献
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G. I. Bizhanova 《Journal of Mathematical Sciences》2000,99(1):816-836
Three one-dimensional problems with free boundary for second order parabolic equations are considered, namely, the Florin, Muskat-Verigin, and Stefan problems. Existence and uniqueness theorems in the weighted Hölder spaces are established for these problems. Coercive estimates for solutions are found. Bibliography:44 titles. 相似文献