A 2-Approximation Algorithm for the Multi-vehicle Scheduling Problem on a Path with Release and Handling Times

  • Authors:
  • Yoshiyuki Karuno;Hiroshi Nagamochi

  • Affiliations:
  • -;-

  • Venue:
  • ESA '01 Proceedings of the 9th Annual European Symposium on Algorithms
  • Year:
  • 2001

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Abstract

In this paper, we consider a scheduling problem of vehicles on a path. Let G = (V, E) be a path, where V = {v1, v2, . . vn} is its set of n vertices and E = {{vj, vj+1} |j = 1, 2, . . .,n - 1} is its set of edges. There are m identical vehicles (1 ≤ m ≤ n). The travel times w(vj, vj+1) (= w(vj+1, vj)) are associated with edges {vj, vj+1} ∈ E. Each job j which is located at each vertex vj ∈ V has release time rj and handling time hj. Any job must be served by exactly one vehicle. The problem asks to find an optimal schedule of m vehicles that minimizes the maximum completion time of all the jobs. The problem is known to be NP-hard for any fixed m ≥ 2. In this paper, we give an O(mn2) time 2-approximation algorithm to the problem, by using properties of optimal gapless schedules.