Efficient algorithms for the double traveling salesman problem with multiple stacks

In this paper we investigate theoretical properties of the Double Traveling Salesman Problem with Multiple Stacks. In particular, we provide polynomial time algorithms for different subproblems when the stack size limit is relaxed. Since these algorithms can represent building blocks for more complex methods, we also include them in a simple heuristic which we test experimentally. We finally analyze the impact of handling the stack size limit, and we propose repair procedures. The theoretical investigation highlights interesting structural properties of the problem, and our computational results show that the single components of the heuristic can be successfully incorporated in more complex algorithms or bounding techniques. (C) 2011 Elsevier Ltd. All rights reserved.