## Abstract

In this paper, we consider the a priori traveling salesman problem (TSP) in the scenario model. In this problem, we are given a list of subsets of the vertices, called scenarios, along with a probability for each scenario. Given a tour on all vertices, the resulting tour for a given scenario is obtained by restricting the solution to the vertices of the scenario. The goal is to find a tour on all vertices that minimizes the expected length of the resulting restricted tour. We show that this problem is already NP-hard and APX-hard when all scenarios have size four. On the positive side, we show that there exists a constant-factor approximation algorithm in three restricted cases: if the number of scenarios is fixed, if the number of missing vertices per scenario is bounded by a constant, and if the scenarios are nested. Finally, we discuss an elegant relation with an a priori minimum spanning tree problem.

Original language | English |
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Pages (from-to) | 183-196 |

Number of pages | 14 |

Journal | Lecture Notes in Computer Science |

Volume | 10138 |

DOIs | |

Publication status | Published - 2017 |

### Bibliographical note

Proceedings title: Approximation and Online Algorithms: 14th International Workshop, WAOA 2016, Aarhus, Denmark, August 25-26, 2016, Revised Selected PapersPublisher: Springer

Place of publication: Berlin

Editors: K. Jansen, M. Mastrolilli