Erratum: the Travelling Salesman and the Pq-Tree

  • Authors:
  • Rainer E. Burkard;Vladimir G. Deineko;Gerhard J. Woeginger

  • Affiliations:
  • -;-;-

  • Venue:
  • Mathematics of Operations Research
  • Year:
  • 1999

Quantified Score

Hi-index 0.00

Visualization

Abstract

Due to a printer's error, incorrect figures were published as part of this paper in Mathematics of Operations Research, Vol. 23, No. 3, August 1998, pp. 613-623. The paper is reprinted correctly below: Let D = (dij) be the n × n distance matrix of a set of n cities {1, 2,...,n}, and let T be a PQ-tree with node degree bounded by d that represents a set Π(T) of permutations over {1, 2,...,n}. We show how to compute for D in O(2dn3) time the shortest travelling salesman tour contained in Π(T). Our algorithm may be interpreted as a common generalization of the well-known Held and Karp dynamic programming algorithm for the TSP and of the dynamic programming algorithm for finding the shortest pyramidal TSP tour. A consequence of our result is that the shortcutting phase of the "twice around the tree" heuristic for the Euclidean TSP can be optimally implemented in polynomial time. This contradicts a statement of Papadimitriou and Vazirani as published in 1984.