The online Prize-Collecting Traveling Salesman Problem (original) (raw)

On Prize-collecting Tours and the Asymmetric Travelling Salesman Problem

International Transactions in Operational Research, 1995

We consider a variant of the Travelling Salesman Problem which is to determine a tour visiting each vertex in the graph at most at one time; if a vertex is left unrouted a given penalty has to be paid. The objective function is to find a balance between these psnalities and the cost of the tour. We call this problem the Profitable Tour Problem (PTP). If, in addition, each vertex is associated with a prize and there is a knapsack constraint which guarantees that a sufficiently large prize is collected, we have the well-known Prize-collecting Travelling Salesman Problem (PC'I~P). In this paper we summarize the main results presented in the literature, then we give lower bounds for the asymmetric version of PTP and PCTSP. Moreover, we show, through computational experiments, that large size instances of the asymmetric PTP can be solved exactly.

Budgeted Prize-Collecting Traveling Salesman and Minimum Spanning Tree Problems

Mathematics of Operations Research, 2019

We consider constrained versions of the prize-collecting traveling salesman and the prize-collecting minimum spanning tree problems. The goal is to maximize the number of vertices in the returned tour/tree subject to a bound on the tour/tree cost. Rooted variants of the problems have the additional constraint that a given vertex, the root, must be contained in the tour/tree. We present a 2-approximation algorithm for the rooted and unrooted versions of both the tree and tour variants. The algorithm is based on a parameterized primal–dual approach. It relies on first finding a threshold value for the dual variable corresponding to the budget constraint in the primal and then carefully constructing a tour/tree that is, in a precise sense, just within budget. We improve upon the best-known guarantee of 2 + ε for the rooted and unrooted tour versions and 3 + ε for the rooted and unrooted tree versions. Our analysis extends to the setting with weighted vertices, in which we want to maxim...

A primal-dual approximation algorithm for the Asymmetric Prize-Collecting TSP

Journal of Combinatorial Optimization, 2012

We present a primal-dual log(n)-approximation algorithm for the version of the asymmetric prize collecting traveling salesman problem, where the objective is to find a directed tour that visits a subset of vertices such that the length of the tour plus the sum of penalties associated with vertices not in the tour is as small as possible. The previous algorithm for the problem (V.H. Nguyen and T.T Nguyen in Int. J. Math. Oper. Res. 4(3):294-301, 2012) which is not combinatorial, is based on the Held-Karp relaxation and heuristic methods such as the Frieze et al.'s heuristic (Frieze et al. in Networks 12:23-39, 1982) or the recent Asadpour et al.'s heuristic for the ATSP (Asadpour et al. in 21st ACM-SIAM symposium on discrete algorithms, 2010). Depending on which of the two heuristics is used, it gives respectively 1 + log(n) and 3 + 8 log(n) log(log(n)) as an approximation ratio. Our algorithm achieves an approximation ratio of log(n) which is weaker than 3 + 8 log(n) log(log(n)) but represents the first combinatorial approximation algorithm for the Asymmetric Prize-Collecting TSP.

Prize-Collecting TSP with a Budget Constraint

2017

We consider constrained versions of the prize-collecting traveling salesman and the minimum spanning tree problems. The goal is to maximize the number of vertices in the returned tour/tree subject to a bound on the tour/tree cost. We present a 2-approximation algorithm for these problems based on a primal-dual approach. The algorithm relies on finding a threshold value for the dual variable corresponding to the budget constraint in the primal and then carefully constructing a tour/tree that is just within budget. Thereby, we improve the best-known guarantees from 3+epsilon and 2+epsilon for the tree and the tour version, respectively. Our analysis extends to the setting with weighted vertices, in which we want to maximize the total weight of vertices in the tour/tree subject to the same budget constraint.

Prize Collecting Travelling Salesman Problem

Proceedings of 5th the International Conference on Operations Research and Enterprise Systems, 2016

The Prize Collecting Travelling Salesman Problem (PCTSP) is an important generalization of the famous Travelling Salesman Problem. It also arises as a sub problem in many variants of the Vehicle Routing Problem. In this paper, we provide efficient methods to solve the linear programming relaxation of the PCTSP. We provide efficient heuristics to obtain the Generalized Subtour Elimination Constraints (GSECs) for the PCTSP, and compare its performance with an optimal separation procedure. Furthermore, we show that a heuristic to separate the primitive comb inequalities for the TSP can be applied to separate the primitive comb inequalities introduced for the PCTSP. We evaluate the effectiveness of these inequalities in reducing the integrality gap for the PCTSP.

Algorithmic View of Online Prize-collecting Optimization Problems

2021

Online algorithms have been a cornerstone of research in network design problems. Unlike in classical offline algorithms, the input to an online algorithm is revealed in portions over time and the online algorithm reacts to each portion while targeting a given optimization goal. Online algorithms are deployed in real-world optimization problems in which provably good decisions are expected in the present without knowing the future. In this paper, we consider a well-established branch of online optimization problems, known as online prizecollecting problems, in which the online algorithm may reject some input portions at the cost of paying an associated penalty. These appear in business applications in which a company decides to lose some customers by paying an associated penalty. Particularly, we study the online prize-collecting variants of three well-known optimization problems: Connected Dominating Set, Vertex Cover, and Non-metric Facility Location, namely, Online Prize-collecting Connected Dominating Set (OPC-CDS), Online Prize-collecting Vertex Cover (OPC-VC), and Online Prize-collecting Non-metric Facility Location (OPC-NFL), respectively. We propose the first online algorithms for these variants and evaluate them using competitive analysis, the standard framework to measure online algorithms, in which the online algorithm is measured against the optimal offline algorithm that knows the entire input sequence in advance and is optimal.

A Tabu Search Approach for the Prize Collecting Traveling Salesman Problem

Electronic Notes in Discrete Mathematics, 2013

The Prize Collecting Traveling Salesman Problem is a generalization of the Traveling Salesman Problem. A salesman collects a prize for each visited city and pays a penalty for each non visited city. The objective is to minimize the sum of the travel costs and penalties, but collecting a minimum pre-established amount of prizes. This problem is here addressed by a simple, but efficient tabu search approach which had improved several upper bounds of the considered instances.

Approximating the asymmetric profitable tour

Electronic Notes in Discrete Mathematics, 2010

We study the version of the asymmetric prize collecting traveling salesman problem, where the objective is to find a directed tour that visits a subset of vertices such that the length of the tour plus the sum of penalties associated with vertices not in the tour is as small as possible. In , the authors defined it as the Profitable Tour Problem (PTP). We present an (1 + log(n))-approximation algorithm for the asymmetric PTP with n is the vertex number. The algorithm that is based on Frieze et al.'s heuristic for the asymmetric traveling salesman problem as well as a method to round fractional solutions of a linear programming relaxation to integers (feasible solution for the original problem), represents a directed version of the Bienstock et al.'s [2] algorithm for the symmetric PTP.

Modeling and Solving the Traveling Salesman Problem with Priority Prizes

Pesquisa Operacional, 2018

This paper addresses the Traveling Salesman Problem with Priority Prizes (TSPPP), an extension of the classical TSP in which the order of the node visits is taken into account in the objective function. A prize p ki is received by the traveling salesman when node i is visited in the k-th order of the route, while a travel cost c i j is incurred when the salesman travels from node i to node j. The aim of the TSPPP is to find the maximum profit n-node tour. The problem can be seen as a TSP variant with a more general objective function, aiming at solutions that in some way consider the quality of customer service and the delivery priorities and costs. A natural representation for the TSPPP is here grounded in the point of view of Koopmans and Beckmann approach, according to which the problem is seem as a special case of the quadratic assignment problem (QAP). Given the novelty of this TSP variant, we propose different mixed integer programming models to appropriately represent the TSPPP, some of them based on the QAP. Computational experiments are also presented when solving the MIP models with a well-known optimization software, as well as with a tabu search algorithm.