SIAM Journal on Discrete Mathematics
Facets of the asymmetric traveling salesman polytope
Mathematics of Operations Research
A polyhedral intersection theorem for capacitated spanning trees
Mathematics of Operations Research
The fixed-outdegree 1-arborescence polytope
Mathematics of Operations Research
A polyhedral approach to the asymmetric traveling salesman problem
Management Science
The vehicle routing problem
Discrete Applied Mathematics - Special issue on the combinatorial optimization symposium
INFORMS Journal on Computing
A new branch-and-cut algorithm for the capacitated vehicle routing problem
Mathematical Programming: Series A and B
Robust Branch-and-Cut-and-Price for the Capacitated Vehicle Routing Problem
Mathematical Programming: Series A and B
Classification of travelling salesman problem formulations
Operations Research Letters
Layered formulation for the robust vehicle routing problem with time windows
ISCO'12 Proceedings of the Second international conference on Combinatorial Optimization
Natural and extended formulations for the Time-Dependent Traveling Salesman Problem
Discrete Applied Mathematics
Hi-index | 0.00 |
We consider two types of hop-indexed models for the unit-demand asymmetric Capacitated Vehicle Routing Problem (CVRP): (a) capacitated models guaranteeing that the number of commodities (paths) traversing any given arc does not exceed a specified capacity; and (b) hop-constrained models guaranteeing that any route length (number of nodes) does not exceed a given value. The latter might, in turn, be divided into two classes: (b1) those restricting the length of the path from the depot to any node k, and (b2) those restricting the length of the circuit passing through any node k. Our results indicate that formulations based upon circuit lengths (b2) lead to models with a linear programming relaxation that is tighter than the linear programming relaxation of models based upon path lengths (b1), and that combining features from capacitated models with those of circuit lengths can lead to formulations for the CVRP with a tight linear programming bound. Computational results on a small number of problem instances with up to 41 nodes and 440 edges show that the combined model with capacities and circuit lengths produce average gaps of less than one percent. We also briefly examine the asymmetric travelling salesman problem (ATSP), showing the potential use of the ideas developed for the vehicle routing problem to derive models for the ATSP with a linear programming relaxation bound that is tighter than the linear programming relaxation bound of the standard Dantzig, Fulkerson and Johnson [G. Dantzig, D. Fulkerson, D. Johnson, Solution of large-scale travelling salesman problem, Operations Research 2 (1954) 393-410] formulation.