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NETWORKS
2006
13 years 12 months ago
Lower bounds for the relative greedy algorithm for approximating Steiner trees
Abstract. The Steiner tree problem is to find a shortest subgraph that spans a given set of vertices in a graph. This problem is known to be NP-hard and it is well known that a pol...
Stefan Hougardy, Stefan Kirchner
NETWORKS
2006
13 years 12 months ago
A bidirected generalization of network matrices
We define binet matrices, which furnish a direct generalization of totally unimodular network matrices and arise from the node-edge incidence matrices of bidirected graphs in the ...
Gautam Appa, Balázs Kotnyek
NETWORKS
2006
13 years 12 months ago
The multiroute maximum flow problem revisited
We are given a directed network G = (V, A, u) with vertex set V , arc set A, a source vertex s V , a destination vertex t V , a finite capacity vector u = {uij}ijA, and a positi...
Donglei Du, R. Chandrasekaran