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671.
We introduce a quantitative parameter measuring m-neighbourliness of symmetric convex polytopes in ℝ
k
. We discuss this parameter for random polytopes generated by subgaussian vectors and show its stability properties.
Research of P. Mankiewicz was partially supported by KBN Grant no. 1 P03A 015 27.
N. Tomczak-Jaegermann holds the Canada Research Chair in Geometric Analysis. 相似文献
672.
673.
When the seats in a parliamentary body are to be allocated proportionally to some given weights, such as vote counts or population data, divisor methods form a prime class to carry out the apportionment. We present a new characterization of divisor methods, via primal and dual optimization problems. The primal goal function is a cumulative product of the discontinuity points of the rounding rule. The variables of the dual problem are the multipliers used to scale the weights before they get rounded. Our approach embraces pervious and impervious divisor methods, and vector and matrix problems. 相似文献
674.
Ashfaque H. Bokhari Munawar Karim Dina N. Al-Sheikh F. D. Zaman 《International Journal of Theoretical Physics》2008,47(10):2672-2678
In this note we consider a general three-dimensional circularly symmetric static metric and investigate possible Killing symmetries it possesses.We then summarize
the work by addressing Einstein equations and briefly discuss their implications on the energy momentum content of some of
the metrics that arise in the process. 相似文献
675.
介绍了熊黎明等人所做的对满足h=n-△(G)的2-连通图的哈密顿指数的一个界限,并将这个界限给予改进并证明,而且还对满足条件的2-连通图做了更进一步的刻划. 相似文献
676.
Juan Marín Jr. Steven M. Seubert 《Journal of Mathematical Analysis and Applications》2007,327(2):1046-1054
The purpose of this paper is to show that various classes of operators having a common collection of root spaces whose closed linear span equals the entire space have dense sets of common cyclic vectors. 相似文献
677.
针对群决策中基于区间数决策矩阵形式偏好信息的专家群体判断共识性问题,提出了一种分析方法.首先,给出了有关区间数的定义及其运算法则;然后,通过定义有关区间数决策矩阵的区间数向量,给出了各个专家与专家群体判断的共识性分析方法,同时,也给出了基于区间数决策矩阵的专家群体判断共识性的判别方法.最后,通过一个算例说明了本文提出的分析方法. 相似文献
678.
Skewed VNS enclosing second order algorithm for the degree constrained minimum spanning tree problem
We develop ideas to enhance the performance of the variable neighborhood search (VNS) by guiding the search in the shaking phase, and by employing the Skewed strategy. For this purpose, Second Order algorithms and Skewed functions expressing structural differences are embedded in an efficient VNS proposed in the literature for the degree constrained minimum spanning tree problem. Given an undirected graph with weights associated with its edges, the degree constrained minimum spanning tree problem consists in finding a minimum spanning tree of the given graph, subject to constraints on node degrees. Computational experiments are conducted on the largest and hardest benchmark instances found in the literature to date. We report results showing that the VNS with the proposed strategies improved the best known solutions for all the hardest benchmark instances. Moreover, these new best solutions significantly reduced the gaps with respect to tight lower bounds reported in the literature. 相似文献
679.
The concept of non-linear self-adjointness for the construction of conservation laws has attracted a lot of interest in recent years. The most noteworthy aspect of it is the likelihood of explicitly constructing the conservation laws for any arbitrary systems of differential equations, in particular for those for which Noether׳s theorem is not applicable. In this study, we shall use both Noether׳s theorem and the non-linear self-adjoint method to construct local and nonlocal conserved vectors of the system of two-dimensional Burgers equations under consideration. The first integrals obtained not only give more credence to obtained results due to their generality with respect to any arbitrary functions of the velocity components but are also independent, nontrivial and infinitely many. 相似文献
680.
In this note, we investigate conformal Killing vectors (CKVs) of locally rotationally symmetric (LRS) Bianchi type V spacetimes. Subject to some integrability conditions, CKVs up to implicit functions of (t,x) are obtained. Solving these integrability conditions in some particular cases, the CKVs are completely determined, obtaining a classification of LRS Bianchi type V spacetimes. The inheriting conformal Killing vectors of LRS Bianchi type V spacetimes are also discussed. 相似文献