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21.
22.
本在无向网络中,建立了带有边集限制的最均匀支撑树问题的网络模型.中首先解决最均匀支撑树问题,并给出求无向网络中最均匀支撑树的多项式时间算法;然后,给出了求无向网络中带有边集限制的最小树多项式时间算法;最后,在已解决的两个问题的基础上解决了带有边集限制的最均匀支撑树问题. 相似文献
23.
TAN Shang-wang GUO Ji-ming QI JianDepartment of Applied Mathematics Petroleum University Dongying China 《数学季刊》2004,19(1):57-62
Let T denote a tree with the diameter d(d≥2) and order n. Let P^*d,r,n-d-1denote the tree obtained by identifying the rth vertex of path Pd l and the center of starKl,K1,n-d-1, where r = r(d) is the integer part about d 2/2. Then p(T)≤ p(P^*d,r,n-d-1), andequality holds if and only if T≌P^*d,r,n-d-1 相似文献
24.
We study computable trees with distinguished initial subtree (briefly, I-trees). It is proved that all I-trees of infinite height are computably categorical, and moreover, they all have effectively infinite computable dimension. 相似文献
25.
A central problem that arises in evolutionary biology is that of displaying partitions of subsets of a finite set X on a tree whose vertices are partially labelled with the elements of X. Such a tree is called an X-tree and, for a collection of partitions of subsets of X, characterisations for the existence and uniqueness of an X-tree that displays have been previously given in terms of chordal graphs. In this paper, we obtain two closely related characterisations also in terms of chordal graphs. The first describes when identifies an X-tree, and the second describes when a compatible subset of is of maximum size. 相似文献
26.
本在Glover—Klingman算法及最小费用支撑树对策的基础上,讨论了最小费用k度限制树对策问题.利用威胁、旁支付理论制订了两种规则,并利用优超、策略等价理论分别给出了在这两种规则下最小费用k度限制树对策核心中的解,从而证明了在这两种规则下其核心非空. 相似文献
27.
M. Brazil 《Discrete Applied Mathematics》2006,154(18):2545-2564
The Steiner problem in a λ-plane is the problem of constructing a minimum length network interconnecting a given set of nodes (called terminals), with the constraint that all line segments in the network have slopes chosen from λ uniform orientations in the plane. This network is referred to as a minimum λ-tree. The problem is a generalization of the classical Euclidean and rectilinear Steiner tree problems, with important applications to VLSI wiring design.A λ-tree is said to be locally minimal if its length cannot be reduced by small perturbations of its Steiner points. In this paper we prove that a λ-tree is locally minimal if and only if the length of each path in the tree cannot be reduced under a special parallel perturbation on paths known as a shift. This proves a conjecture on necessary and sufficient conditions for locally minimal λ-trees raised in [M. Brazil, D.A. Thomas, J.F. Weng, Forbidden subpaths for Steiner minimum networks in uniform orientation metrics, Networks 39 (2002) 186-222]. For any path P in a λ-tree T, we then find a simple condition, based on the sum of all angles on one side of P, to determine whether a shift on P reduces, preserves, or increases the length of T. This result improves on our previous forbidden paths results in [M. Brazil, D.A. Thomas, J.F. Weng, Forbidden subpaths for Steiner minimum networks in uniform orientation metrics, Networks 39 (2002) 186-222]. 相似文献
28.
STRONG LAW OF LARGE NUMBERS AND ASYMPTOTIC EQUIPARTITION PROPERTY FOR NONSYMMETRIC MARKOV CHAIN FIELDS ON CAYLEY TREES 总被引:1,自引:0,他引:1
Some strong laws of large numbers for the frequcncies of occurrence of states and ordered couples of states for nonsymmetric Markov chain fields(NSMC)on Cayley trees are studied.In the proof,a new technique for the study of strong liinit theorems of Markov chains is extended to the case of Markov chain fields.The asymptotic equiparti- tion properties with almost everywhere(a.e.)convergence for NSMC on Cayley trees are obtained. 相似文献
29.
The authors consider the limiting behavior of various branches in a uniform recursive tree with size growing to infinity.The limiting distribution ofζ_(n,m),the number of branches with size m in a uniform recursive tree of order n,converges weakly to a Poisson distribution with parameter 1/m with convergence of all moments.The size of any large branch tends to infinity almost surely. 相似文献
30.
Asiswellknown,thetheoryfornonlinearpolymerizationswasinitiatedbyFloryandStockmayer[1—3].MillerandMacosko[4—6]proposedarecursivemethodfordealingwiththeproblemofthepostgelpropertiesofthenetworkformingpolymerization.Stepto[7]investigatedthegelgelreactionofRAft… 相似文献