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An algorithm for the hierarchical Chinese postman problem

2000, Operations Research Letters

Abstract

The Hierarchical Chinese Postman Problem (HCPP) is a variant of the classical Chinese Postman Problem, in which the arcs are partitioned into clusters and a precedence relation is deÿned on clusters. Practical applications of the HCPP include snow and ice control on the roads and determination of optimal torch paths in ame cutting. The HCPP is NP-hard in general, but polynomial-time solvable if the precedence relation is linear and each cluster is connected. For this case an exact algorithm, requiring a lower computational e ort than previous procedures, is described. and no edge in E i can be traversed before the traversal of all edges in E i−1 is completed. This variant of the HCPP has been used to model some practical problems: the determination of optimal torch paths in ame cutting [10] and snow removal operations in an urban or rural setting where streets are classiÿed according to their importance (generally expressed by the average daily tra c) . Lemieux and Campagna [9] give simple heuristic procedures for a snow plowing problem in which streets are classiÿed into main and secondary streets. Alfa and Liu [1] consider a weaker precedence relation requiring that the traversal of E i starts before the beginning of the traversal of E i+1 and ÿnishes before the ending of the traversal of E i+1 . Dror et al. give a necessary and su cient condition for the existence of a feasible solution and show that the HCPP 0167-6377/00/$ -see front matter c 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 -6 3 7 7 ( 9 9 ) 0 0 0 4 6 -2