A savings based method for real-life vehicle routing problems

This paper describes a Savings Based algorithm for the Extended Vehicle Routing Problem. This algorithm is compared with a Sequential Insertion algorithm on real-life data. Besides the traditional quality measures such as total distance traveled and total workload, we compare the routing plans of both algorithms according to non-standard quality measures that help to evaluate the "visual attractiveness" of the plan. Computational results show that, in general, the Savings Based algorithm not only performs better with respect to these non-standard quality measures, but also with respect to the traditional measures.distribution;vehicle routing;road transport

Finding a Feasible Solution for a Simple LP Problem using Agents

In this paper we will describe a Multi-Agent System which is capable of finding a feasible solution of a specially structured linear programming problem. Emphasis is given to correctness issues and termination detection.multi-agent systems;linear programming

On the P-Coverage Problem on the Real Line

In this paper we consider the p-coverage problem on the real line. We first give a detailed description of an algorithm to solve the coverage problem without the upper bound p on the number of open facilities. Then we analyze how the structure of the optimal solution changes if the setup costs of the facilities are all decreased by the same amount. This result is used to develop a parametric approach to the p-coverage problem which runs in o (pn logn) time, n being the number of clients

Rostering at a Dutch Security Firm

The roster planning process at the Dutch security firm NVD was traditionally carried out by hand. A few years NVD was traditionally carried out by hand. A few years ago, because of changing labor laws in the Netherlands, this became practically impossible. We developed a decision support system which has four main modules. The first one checks given rosters for feasibility with respect to the complicated rules of the current Collective Labor Agreement. A second module generates feasible rosters. The third one evaluates each roster with respect to its cost and ergonomic criteria. Finally, the fourth module uses mathematical programming based methods to select high quality rosters. The DSS has received rave reviews from upper management, security employees as well as the planners, who have gained enormous insight into the planning process. The DSS is currently being implemented and will be operational within the near future.decision support systems;information systems;labor;applications;integer;programming;search and surveillance

A savings based method for real-life vehicle routing problems

This paper describes a Savings Based algorithm for the Extended Vehicle Routing Problem. This algorithm is compared with a Sequential Insertion algorithm on real-life data. Besides the traditional quality measures such as total distance traveled and total workload, we compare the routing plans of both algorithms according to non-standard quality measures that h

Economic Lot-Sizing with Start-up Costs: The Convex Hull

A partial description of the convex hull of solutions to the economic lot-sizing problem with start-up costs (ELSS) has been derived recently. Here a larger class of valid inequalities is given and it is shown that these inequalities describe the convex hull of ELSS. This in turn proves that a plant location formulation as a linear program solves ELSS. Finally a separation algorithm is given

Rostering at a Dutch Security Firm

The roster planning process at the Dutch security firm NVD was traditionally carried out by hand. A few year

Sensitivity Analysis of List Scheduling Heuristics

When jobs have to be processed on a set of identical parallel machines so as to minimize the makespan of the schedule, list scheduling rules form a popular class of heuristics. The order in which jobs appear on the list is assumed here to be determined by the relative size of their processing times; well known special cases are the LPT rule and the SPT rule, in which the jobs are ordered according to non-increasing and non-decreasing processing time respectively. When one of the job processing times is gradually increased, the schedule produced by a list scheduling rule will be affected in a manner reflecting its sensitivity to data perturbations. We analyze this phenomenon and obtain analytical support for the intuitively plausible notion that the sensitivity of a list scheduling rule increases with the quality of the schedule produced