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In this paper we address the Optimum Communication Spanning Tree Problem. We present a formulation that uses three index variables and we propose several families of inequalities, which can be used to reinforce the formulation. Preliminary computational experiments are very promising. 相似文献
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树映射有异状点的一个充要条件 总被引:8,自引:0,他引:8
讨论了树上连续自映射的拓扑熵与非稳定流形之间的关系. 证明了:树上连续自映射有异状点的充要条件是其拓扑熵大于零. 因而推广了区间上连续自映射的一个结果. 相似文献
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Let k ≥ 2 be an integer. We show that if G is a (k + 1)-connected graph and each pair of nonadjacent vertices in G has degree sum at least |G| + 1, then for each subset S of V(G) with |S| = k, G has a spanning tree such that S is the set of endvertices. This result generalizes Ore’s theorem which guarantees the existence of a Hamilton path connecting
any two vertices.
Dedicated to Professor Hikoe Enomoto on his 60th birthday. 相似文献
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G为图且T是G的一棵生成树. 记号ξ(G, T)表示G\E(T)中边数为奇数的连通分支个数. 文献[2]称ξ(G)=min[DD(X]T[DD)]ξ(G, T)为图G的Betti亏数, 这里min取遍G的所有生成树T. 由文献[2]知, 确定一个图G的最大亏格主要确定这个图的Betii亏数ξ(G).该文研究与Betti亏数有关的图的特征结构, 得到了关于图的最大亏格的若干结果. 相似文献
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In this paper . we obtained a necessary and sufficient condition for the existence of parabolic separatrix cycles in a quadratic system, and drawed its all possible phase-portraits. Further we obtain an accurate parameter interval that a Ⅲ type system exist ltmit cycles. 相似文献
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讨论了一维奇异P-Laplace方程{φp(u′))′ f(t,u)=0,t∈(0,1);u(0=u(1)=0存在C^1[0,1]或C[0,1]正解的一个充分必要条件.用到的方法主要有上下解方法和Schaude,不动点定理. 相似文献
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温一慧 《数学的实践与认识》2009,39(19)
指出了一类边裂图SEP(K1,n,f)与图K1,n的边优美性的差异.得到了对任意自然数m>0,SPE(K1,4m+1,f)不是边优美的,以及SEP(K1,n,f)是边优美图的充要条件. 相似文献
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本文在平面上解决了StevenRLay在 [1 ]中提出的开放性问题“什么样的凸集存在唯一的最小凸生成子集” ,给出并证明了“平面上的凸集存在唯一的最小凸生成子集”的一个充要条件 .同时证明了En 中的开集一定不存在最小凸生成集 . 相似文献
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A spanning tree of a properly edge-colored complete graph, , is rainbow provided that each of its edges receives a distinct color. In 1996, Brualdi and Hollingsworth conjectured that if is properly -edge-colored, then the edges of can be partitioned into rainbow spanning trees except when . By means of an explicit, constructive approach, in this paper we construct mutually edge-disjoint rainbow spanning trees for any positive value of . Not only are the rainbow trees produced, but also some structure of each rainbow spanning tree is determined in the process. This improves upon best constructive result to date in the literature which produces exactly three rainbow trees. 相似文献
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给出了积分因子存在的一般充分必要条件和计算公式.为寻找一阶微分方程的积分因子提供了一个一般方法.并举例说明定理的应用. 相似文献
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本文给出了中心对称三次系统存在双曲线分界线环的充要条件,并证明了此系统还可以至少存在五个极限环。 相似文献
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设f:Rn→ Rn是一同胚,该文证明了 f 是拟共形映射的充要条件是 f 将 Rn 中的任一John域映成 Rn 中的John域. 相似文献
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考虑全空间R^R上的空间-△↓(|△↓u|^p-2△↓u)=ρ(x)u^α存在有界解的充分必要条件。 相似文献
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Let a, b, be two even integers. In this paper, we get a sufficient condition which involves the stability number, the minimum degree of the graph for the existence of an even [a, b]-factor. 相似文献
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通过Green函数给出了一对具体的上下解,对一类奇异微分方程边值问题做了研究,得到正解存在的充分必要条件. 相似文献
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Aung Kyaw 《Graphs and Combinatorics》2001,17(1):113-121
A k-tree of a connected graph is a spanning tree with maximum degree at most k. We obtain a sufficient condition for a graph
to have a k-tree, as a generalization of the condition of E. Flandrin, H. A. Jung and H. Li [3] for traceability. We also
extend early results of Y. Caro, I. Krasikov and Y. Roditty [2] and Min Aung and Aung Kyaw [4] for the maximal order of a
tree with bounded maximum degree in a graph.
Received: July 28, 1997 Final version received: April 13, 1998 相似文献