共查询到17条相似文献,搜索用时 62 毫秒
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最小度生成树问题是一个NP难问题.本文给出了求最小度生成树的一种近似算法,这种算法得到的生成树的度数比最优解至多大1. 相似文献
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《数学的实践与认识》2015,(12)
在点、边赋权的简单图中,关于最小权点覆盖问题,以经典的最短路算法-Dijkstra算法为基础,提出了一个求解该问题的近似算法.首先,在给定的赋权图中任选一点作为初始点,并给出允许集及相关定义.然后,利用经典的最短路算法-Dijkstra算法,求出初始点到允许集中各顶点的最短路径,并按照一定的原则选择近似最小权点覆盖集.最后,通过算例阐释了算法的实现过程的合理性及有效性. 相似文献
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翟晓燕 《应用数学与计算数学学报》1999,13(2):87-93
本文通过对网络中有向支撑出树性质的研究,提出了在有向网络图中寻找以某一定点为根的最小有向支撑出树一种较简便的计算方法,并给出了应用该算法进行实际操作的一个算例. 相似文献
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研究了单位$l_{\infty}$ 范数下边权有界的最小支撑树逆最优值问题。给定一个边赋权无向连通网络$G=(V, E, w)$ , 支撑树$T^0$ , 下界向量$\bm{l}$ , 上界向量$\bm{u}$ 及数值$K$ , 寻求一个新的边权向量$\bm{\bar{w}}$ 满足上下界约束$\bm{l}\le\bar{\bm w}\le {\bm u}$ , 且$T^0$ 是在向量$\bm{\bar{w}}$ 下权值为$K$ 的一个最小支撑树, 目标是在单位$l_{\infty}$ 范数下使得修改成本$\|\bar{\bm w}-{\bm w}\|$ 最小。本文给出了该问题的数学模型, 分析了其最优性条件, 设计了求解该问题的时间复杂度为$O(|V||E|)$ 的强多项式时间算法。 相似文献
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研究了单位$l_{\infty}$ 范数下边权有界的最小支撑树逆最优值问题。给定一个边赋权无向连通网络$G=(V, E, w)$ , 支撑树$T^0$ , 下界向量$\bm{l}$ , 上界向量$\bm{u}$ 及数值$K$ , 寻求一个新的边权向量$\bm{\bar{w}}$ 满足上下界约束$\bm{l}\le\bar{\bm w}\le {\bm u}$ , 且$T^0$ 是在向量$\bm{\bar{w}}$ 下权值为$K$ 的一个最小支撑树, 目标是在单位$l_{\infty}$ 范数下使得修改成本$\|\bar{\bm w}-{\bm w}\|$ 最小。本文给出了该问题的数学模型, 分析了其最优性条件, 设计了求解该问题的时间复杂度为$O(|V||E|)$ 的强多项式时间算法。 相似文献
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在有向网络中寻找最小支撑入树的计算方法 总被引:1,自引:0,他引:1
翟晓燕 《数学的实践与认识》2002,32(6):973-978
本文研究了有向网络中支撑入树的性质 ,提出了在有向网络图中寻找以某一指定点为根的最小支撑入树的一种较简便的算法 ,并给出了应用该算法的一个实际算例 相似文献
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针对具有n个通讯站的局域网络,运用增加或调整虚设站的方法,给出一种在混合距离下的极小费用生成树的算法.并就MCM91问题B,求出了极小费用生成树,其总费用小于美国马里兰州里斯勃来莱州立大学数学科学系B.A.Fusaro所提供的论文中的费用. 相似文献
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DachuanXu GuanghuiLiu 《应用数学学报(英文版)》2003,19(2):289-296
Given a directed graph G and an edge weight function w : A(G)→ R^ , the maximum directed cut problem (MAX DICUT) is that of finding a directed cut δ(S) with maximum total weight. We consider a version of MAX DICUT -- MAX DICUT with given sizes of parts or MAX DICUT WITH GSP -- whose instance is that of MAX DICUT plus a positive integer k, and it is required to find a directed cut δ(S) having maximum weight over all cuts δ(S) with |S| -- k. We present an approximation algorithm for this problem which is based on semidefinite programming (SDP) relaxation. The algorithm achieves the presently best performance guarantee for a range of k. 相似文献
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The vector partition problem concerns the partitioning of a set A of n vectors in d-space into p parts so as to maximize an objective function c which is convex on the sum of vectors in each part. Here all parameters d, p, n are considered variables. In this paper, we study the adjacency of vertices in the associated partition polytopes. Using our adjacency characterization for these polytopes, we are able to develop an adaptive algorithm for the vector partition problem that runs in time O(q(L)v) and in space O(L), where q is a polynomial function, L is the input size and v is the number of vertices of the associated partition polytope. It is based on an output-sensitive algorithm for enumerating all vertices of the partition polytope. Our adjacency characterization also implies a polynomial upper bound on the combinatorial diameter of partition polytopes. We also establish a partition polytope analogue of the lower bound theorem, indicating that the output-sensitive enumeration algorithm can be far superior to previously known algorithms that run in time polynomial in the size of the worst-case output. 相似文献
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We study the Pareto optimal equilibria payoffs of the non-cooperative game associated with the cost spanning tree problem.
We give two characterisations of these payoffs: one based on the tree they induce and another based on the strategies played
by agents. Moreover, an algorithm for computing all these payoffs is provided. 相似文献