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A routing tree for a set of tasks is a decision tree which assigns the tasks to their destinationsaccording to the features of the tasks. A weighted routing tree is one with costs attached to each linkof the tree. Links of the same feature have the same cost. It is proved that the problem of finding ?routing tree of the minimum cost for a given set of tasks of two features is NP-complete. 相似文献
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This paper considers a first passage model for discounted semi-Markov decision processes with denumerable states and nonnegative costs.The criterion to be optimized is the expected discounted cost incurred during a first passage time to a given target set.We first construct a semi-Markov decision process under a given semi-Markov decision kernel and a policy.Then,we prove that the value function satisfies the optimality equation and there exists an optimal(or e-optimal) stationary policy under suitable conditions by using a minimum nonnegative solution approach.Further we give some properties of optimal policies.In addition,a value iteration algorithm for computing the value function and optimal policies is developed and an example is given.Finally,it is showed that our model is an extension of the first passage models for both discrete-time and continuous-time Markov decision processes. 相似文献
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For a strongly connected digraph D the minimum ,cardinality of an arc-cut over all arc-cuts restricted arc-connectivity λ′(D) is defined as the S satisfying that D - S has a non-trivial strong component D1 such that D - V(D1) contains an arc. Let S be a subset of vertices of D. We denote by w+(S) the set of arcs uv with u ∈ S and v S, and by w-(S) the set of arcs uv with u S and v ∈ S. A digraph D = (V, A) is said to be λ′-optimal if λ′(D) =ξ′(D), where ξ′(D) is the minimum arc-degree of D defined as ξ(D) = min {ξ′(xy) : xy ∈ A}, and ξ′(xy) = min(|ω+({x,y})|, |w-({x,y})|, |w+(x) ∪ w- (y) |, |w- (x) ∪ω+ (y)|}. In this paper a sufficient condition for a s-geodetic strongly connected digraph D to be λ′-optimal is given in terms of its diameter. Furthermore we see that the h-iterated line digraph Lh(D) of a s-geodetic digraph is λ′-optimal for certain iteration h. 相似文献
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§1. Introduction For a ?nite, simple, and undirected graph X, every edge of X gives rise to a pair ofopposite arcs, and we denote by V (X), E(X), A(X) and Aut(X) the vertex set, the edgeset, the arc set and the automorphism group of X, respectively. … 相似文献
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We extend a theorem of Ivanev and Saff to show that for the Hermite-Pade interpolant at the roots of unity to a function meromorphic in the unit disc, its leading coefficients vanish if and only if the corresponding interpolani to a related function vanishes at given points outside the unit disc. The result is then extended to simultaneous Hermite-Pade interpolation to a finite set of functions. 相似文献
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ZhangShaoqiang LiGuojun SohnMoo-Young 《高校应用数学学报(英文版)》2004,19(2):149-154
Many difficult (often NP-complete) optimization problems can be solved efficiently on graphs of small tree-width with a given tree decomposition. In this paper,it is discussed how to solve the minimum feedback vertex set problem and the minimum vertex feedback edge set problem efficiently by using dynamic programming on a tree-decomposition. 相似文献
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A refinement about estimation of expansion coefficients for normalized biholomorphic mappings 总被引:4,自引:0,他引:4
LIU Taishun & LIU Xiaosong Department of Mathematics University of Science Technology of China Hefei China 《中国科学A辑(英文版)》2005,48(7):865-879
A refining estimation of homogeneous expansion for / is discussed, where f belongs to a subclass of all normalized biholomorphic mappings defined on the unit polydisk in Cn or the unit ball in complex Banach spaces, and x = 0 is a zero of order k 1 of f(x)-x. Moreover, an estimation of homogeneous expansion for subordinate mappings defined on the unit ball in complex Banach spaces is also given. 相似文献
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The singularity theory of dynamical systems is linked to the numerical computation of boundary value problems of differential equations. It turns out to be a modified least square method for a calculation of variational problem defined on Ck(Ω), in which the base functions are polynomials and the computation of problems is transferred to compute the coefficients of the base functions. The theoretical treatment and some simple examples are provided for understanding the modification procedure of the methods. A modified least square method on difference scheme is introduced with a general matrix form of dynamical systems. We emphasize the simplicity of the algorithm and only use Euler algorithm to compute initial value problems of ODEs. A better algorithm is needed to reduce the stiffness of ODEs. 相似文献
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1 IntroductionIn [2] tl1e authors considered a type of coustrained maximim capacity path problem whichcan be described briefly as: kuowing the costs for expallding one unit of capacity along differentedge8 of a l1etwork aud the availabIe budget, how to iucrease the caparities of the edges so thattlle capasity between any pair of nodes in the lletwork can be raised unifornily to the maximumextent? As the total cost is a summation of the expansion costs on all edges, this problem i8related to mi… 相似文献
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Let G = (V,E) be a graph without isolated vertices.A set S V is a domination set of G if every vertex in V - S is adjacent to a vertex in S,that is N[S] = V.The domination number of G,denoted by γ(G),is the minimum cardinality of a domination set of G.A set S C V is a paired-domination set of G if S is a domination set of G and the induced subgraph G[S] has a perfect matching.The paired-domination number,denoted by γpr(G),is defined to be the minimum cardinality of a paired-domination set S in G.A subset S V is a power domination set of G if all vertices of V can be observed recursively by the following rules: (i) all vertices in N[S] are observed initially,and (ii) if an observed vertex u has all neighbors observed except one neighbor v,then v is observed (by u).The power domination number,denoted by γp(G),is the minimum cardinality of a power domination set of G.In this paper,the constructive characterizations for trees with γp = γ and γpr = γp are provided respectively. 相似文献
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ON SYMMETRIC SCALAR CURVATURE ON 总被引:1,自引:0,他引:1
JI Min 《数学年刊B辑(英文版)》1999,20(3):325-330
1.IntroductionGivenacontinuousfunctionRonthestandardsphereS',itisaninterestingproblemwhetherRcanbethescalarcurvatureofsomemetricgwhichispointwiseconformaltothestandardmetricgoonS2.Ifwesetg~e"go,whereuisafunctiononS',theproblemisequivalenttothesolvabilityofthefollowingPDE:--A..u 2--Re"=0,onS2.(l'1)KazdanandWarner[9]pointedoutthatitmaybeinsolvable.Inthelastfewyears,alotofworkhasbeendonetosolveproblem(l.l),especiallywhenRpossessessomekindsofsymmetries.AfterthepioneerworkduetoMoser[lo]forthe… 相似文献
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D. VENDRUSCOLO 《数学年刊B辑(英文版)》2005,26(2):315-322
§ 1 . IntroductionQuestions about bounds for indices ?rst appeared in the ?xed point context. The ?rstresults appeared in studies of surface homeomorphisms (see [13, 18, 19]). In [12, 14] and[15] some results about bounds for Nielsen ?xed point class ind… 相似文献
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本文研究了一类曲面的无穷小Ⅰ(Ⅲ)—等距,得到了两个整体定理,并由此证明了在适当的边界条件下,特殊Weingarten曲面M的无穷小Ⅰ(Ⅲ)—等距Φ是关于M的无穷小刚体运动。 相似文献
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《Quaestiones Mathematicae》2013,36(4):339-350
Abstract In this note we prove an extension of B. de Pagter's theorem (positive, compact, irreducible operators on Banach lattices are not quasi-nilpotent) for positive, band irreducible operators on Banach lattices satisfying some additional conditions. 相似文献
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