2-Path Cuts for the Vehicle Routing Problem with Time Windows
Transportation Science
A Branch-and-Cut Procedure for the Vehicle Routing Problem with Time Windows
Transportation Science
Vehicle routing problem with elementary shortest path based column generation
Computers and Operations Research
A general heuristic for vehicle routing problems
Computers and Operations Research
Optimizing over the first Chvátal closure
Mathematical Programming: Series A and B
The Shortest-Path Problem with Resource Constraints and k-Cycle Elimination for k ≥ 3
INFORMS Journal on Computing
Subset-Row Inequalities Applied to the Vehicle-Routing Problem with Time Windows
Operations Research
Lagrangian duality applied to the vehicle routing problem with time windows
Computers and Operations Research
New Route Relaxation and Pricing Strategies for the Vehicle Routing Problem
Operations Research
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The Vehicle Routing Problem with Time Windows (VRPTW) requires to design minimum cost routes for a fleet of vehicles with identical capacities to serve a set of customers within given time windows. Each customer must be visited exactly once and the load of a vehicle must not exceed its capacity. In this paper we introduce two new basic families of valid inequalities, called Lifted and Local Reachability Cuts, respectively, which extend the Reachability Cuts introduced by J. Lysgaard. Separation procedures for Lifted and Local Reachability Cuts have been implemented and embedded into a Branch-and-Cut framework to validate their computational effectiveness. They were tested on the Solomon and on the Gehring-Homberger benchmark instances (also known as the ''Extended Solomon'' instances) with 200 customers. Computational experiments show that the new cutting plane families can substantially improve the lower bounds returned by Lysgaard's Reachability Cuts. The Branch-and-Cut algorithm could also provide the optimal solution of three previously unsolved instances - C222, C225 and C226 - with large capacities and wide time windows and therefore difficult for exact algorithms.