Improved Steiner tree approximation in graphs
SODA '00 Proceedings of the eleventh annual ACM-SIAM symposium on Discrete algorithms
Approximating the Single-Sink Link-Installation Problem in Network Design
SIAM Journal on Optimization
An Approximation Algorithm for Minimum-Cost Network Design
An Approximation Algorithm for Minimum-Cost Network Design
An improved approximation algorithm for capacitated multicast routings in networks
Theoretical Computer Science
Improved approximation algorithms for the capacitated multicast routing problem
COCOON'05 Proceedings of the 11th annual international conference on Computing and Combinatorics
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Let G=(V,E) be a connected graph such that each edge e驴E is weighted by a nonnegative real w(e). Let s be a vertex designated as a sink, M驴V be a set of terminals with a demand function q:M驴R +, 驴0 be a routing capacity, and 驴驴1 be an integer edge capacity. The capacitated tree-routing problem (CTR) asks to find a partition 驴={Z 1,Z 2,驴,Z 驴 } of M and a set ${\mathcal{T}}=\{T_{1},T_{2},\ldots,T_{\ell}\}$ of trees of G such that each T i contains Z i 驴{s} and satisfies $\sum_{v\in Z_{i}}q(v)\leq \kappa$ . A single copy of an edge e驴E can be shared by at most 驴 trees in ${\mathcal{T}}$ ; any integer number of copies of e are allowed to be installed, where the cost of installing a copy of e is w(e). The objective is to find a solution $({\mathcal{M}},{\mathcal{T}})$ that minimizes the total installing cost. In this paper, we propose a (2+驴 ST )-approximation algorithm to CTR, where 驴 ST is any approximation ratio achievable for the Steiner tree problem.