Approximation Algorithms for Some Postman Problems
Journal of the ACM (JACM)
Combinatorial Optimization: Theory and Algorithms
Combinatorial Optimization: Theory and Algorithms
Analysis of Christofides' heuristic: Some paths are more difficult than cycles
Operations Research Letters
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Given a weighted undirected graph G=(V,E), where the vertex set V is partitioned into K clusters V"1,...,V"K, the clustered traveling salesman problem is to compute a shortest tour so that all vertices are visited and the vertices of each cluster are visited consecutively. Supposing that no starting and ending vertices of any cluster are specified, we provide a 13/6(~2.17)-approximation algorithm, and improve the previous approximation ratio of 2.75 due to Guttmann-Beck, Hassin, Khuller, and Raghavachari [Algorithmica 28 (2000) 422-437].