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951.
In this article, we consider the maximum cocliques of the 211: M24 ‐graph Λ. We show that the maximum cocliques of size 24 of Λ can be obtained from two Hadamard matrices of size 24, and that there are exactly two maximum cocliques up to equivalence. We verify that the two nonisomorphic designs with parameters 5‐(24,9,6) can be constructed from the maximum cocliques of Λ, and that these designs are isomorphic to the support designs of minimum weights of the ternary extended quadratic residue and Pless symmetry [24,12,9] codes. Further, we give a new construction of Λ from these 5‐(24,9,6) designs. © 2009 Wiley Periodicals, Inc. J Combin Designs 17: 323–332, 2009 相似文献
952.
Mykhaylo Tyomkyn 《Discrete Mathematics》2009,309(20):5963-5967
Bonato and Tardif [A. Bonato, C. Tardif, Mutually embeddable graphs and the tree alternative conjecture, J. Combinatorial Theory, Series B 96 (2006), 874-880] conjectured that the number of isomorphism classes of trees mutually embeddable with a given tree T is either 1 or infinite. We prove the analogue of their conjecture for rooted trees. We also make some progress towards the original conjecture for locally finite trees and state some new conjectures. 相似文献
953.
Pinar Heggernes 《Discrete Mathematics》2006,306(3):297-317
Any given graph can be embedded in a chordal graph by adding edges, and the resulting chordal graph is called a triangulation of the input graph. In this paper we study minimal triangulations, which are the result of adding an inclusion minimal set of edges to produce a triangulation. This topic was first studied from the standpoint of sparse matrices and vertex elimination in graphs. Today we know that minimal triangulations are closely related to minimal separators of the input graph. Since the first papers presenting minimal triangulation algorithms appeared in 1976, several characterizations of minimal triangulations have been proved, and a variety of algorithms exist for computing minimal triangulations of both general and restricted graph classes. This survey presents and ties together these results in a unified modern notation, keeping an emphasis on the algorithms. 相似文献
954.
曲率二次衰减的完备流形的基本群 总被引:1,自引:0,他引:1
本文研究曲率二次衰减的完备黎曼流形,证明了若它的直径增长满足小的线性增长条件,则其基本群是有限生成的. 相似文献
955.
The first step toward developing complete cell circuitry is to build quantitative networks for enzyme reactions. The conventional King-Altman-Hill (KAH) algorithm for topological analysis of enzyme networks, adapted from electrical networks, is based on “Reaction Graphs” that, unlike electrical circuits, are not quantitative, being straightforward renderings of conventional schematics of reaction mechanisms. Therefore, we propose the use of “Reaction Route (RR) Graphs” instead, as a more suitable graph-theoretical representation for topological analysis of enzyme reaction networks. The RR Graphs are drawn such that they are not only useful for visualizing the various reaction routes or pathways, but unlike Reaction Graphs possess network properties consistent with requisite kinetic, mass balance, and thermodynamic constraints. Therefore, they are better than the conventional Reaction Graphs for topological representation and analysis of enzyme reactions, both via the KAH methodology as well as via numerical matrix inversion. The difference between the two is highlighted based on the example of a single enzyme reaction network for the conversion of 7,8-dihydrofolate and NADPH into 5,6,7,8-tetrahydrofolate and NADP+, catalyzed by the enzyme dihydrofolate reductase. 相似文献
956.
Zsolt Katona 《Random Structures and Algorithms》2006,29(2):194-207
Consider the random graph model of Barabási and Albert, where we add a new vertex in every step and connect it to some old vertices with probabilities proportional to their degrees. If we connect it to only one of the old vertices the graph will be a tree. These graphs have been shown to have power law degree distributions, the same as observed in some large real‐world networks. We show that the degree distribution is the same on every sufficiently high level of the tree. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2006 相似文献
957.
Enrique Miranda Gert de Cooman Erik Quaeghebeur 《Journal of Theoretical Probability》2007,20(3):663-693
We investigate to what extent finitely additive probability measures on the unit interval are determined by their moment sequence.
We do this by studying the lower envelope of all finitely additive probability measures with a given moment sequence. Our
investigation leads to several elegant expressions for this lower envelope, and it allows us to conclude that the information
provided by the moments is equivalent to the one given by the associated lower and upper distribution functions. 相似文献
958.
959.
专利联盟许可行为的博弈分析 总被引:1,自引:0,他引:1
专利联盟这一新的经济组织近年来引起了众多学者的关注。本文以Shapiro Carl(2000)的模型为基础,从博弈论的角度对互补性专利持有企业的许可行为进行了研究,并将其对产品市场的影响作了进一步的比较分析,研究表明:专利联盟内的协调、约束机制的存在是企业的获得较高许可收益的保证,并且联盟可以提高产品市场的均衡产量,降低单位产品的成本和价格,改善社会福利水平。 相似文献
960.
Ying Ying TAN Yi Zheng FAN 《数学学报(英文版)》2008,24(1):139-146
Let G be a mixed glaph which is obtained from an undirected graph by orienting some of its edges. The eigenvalues and eigenvectors of G are, respectively, defined to be those of the Laplacian matrix L(G) of G. As L(G) is positive semidefinite, the singularity of L(G) is determined by its least eigenvalue λ1 (G). This paper introduces a new parameter edge singularity εs(G) that reflects the singularity of L(G), which is the minimum number of edges of G whose deletion yields that all the components of the resulting graph are singular. We give some inequalities between εs(G) and λ1 (G) (and other parameters) of G. In the case of εs(G) = 1, we obtain a property on the structure of the eigenvectors of G corresponding to λ1 (G), which is similar to the property of Fiedler vectors of a simple graph given by Fiedler. 相似文献