MO-ParamILS: A Multi-objective Automatic Algorithm Configuration Framework

International audienceAutomated algorithm configuration procedures play an increasingly important role in the development and application of algorithms for a wide range of computationally challenging problems. Until very recently, these configuration procedures were limited to optimising a single performance objective, such as the running time or solution quality achieved by the algorithm being configured. However, in many applications there is more than one performance objective of interest. This gives rise to the multi-objective automatic algorithm configuration problem, which involves finding a Pareto set of configurations of a given target algorithm that characterises trade-offs between multiple performance objectives. In this work, we introduce MO-ParamILS, a multi-objective extension of the state-of-the-art single-objective algorithm configuration framework ParamILS, and demonstrate that it produces good results on several challenging bi-objective algorithm configuration scenarios compared to a base-line obtained from using a state-of-the-art single-objective algorithm configurator

Increasing Sustainability of Logistic Networks by Reducing Product Losses: A Network DEA Approach

This paper considers a multiproduct supply network, in which losses (e.g., spoilage of perishable products) can occur at either the nodes or the arcs. Using observed data, a Network Data Envelopment Analysis (NDEA) approach is proposed to assess the efficiency of the product flows in varying periods. Losses occur in each process as the observed output flows are lower than the observed input flows. The proposed NDEA model computes, within the NDEA technology, input and output targets for each process. The target operating points correspond to the minimum losses attainable using the best observed practice. The efficiency scores are computed comparing the observed losses with the minimum feasible losses. In addition to computing relative efficiency scores, an overall loss factor for each product and each node and link can be determined, both for the observed data and for the computed targets. A detailed illustration and an experimental design are used to study and validate the proposed approach. The results indicate that the proposed approach can identify and remove the inefficiencies in the observed data and that the potential spoilage reduction increases with the variability in the losses observed in the different periods

A simple search heuristic for the MCLP: Application to the location of ambulance bases in a rural region

In the location of ambulance bases for medical assistance, an adequate time of response must be guaranteed for each area in the region covered, incurring the minimum operating costs. Several linear models (such as the maximal covering location problem, MCLP) have been developed for designing these emergency systems which guarantee a certain cover whilst minimising determined costs. The computational difficulty involved in resolving large scale problems occasionally means trying to offer solutions using metaheuristics. This article presents the solution to the problem of locating ambulance bases in the province of Leøn (Spain), using the tabu search metaheuristic, which in its simplest version already offers good results, and which makes it a tool to be kept very much in mind when a rapid solution is needed to such problems.location ambulance service emergency medical service location tabu search

Centralised target setting for regional recycling operations using DEA

This paper presents an application of data envelopment analysis for analysing the performance of a number of spanish municipalities in terms of the amount of glass recycled. The inputs considered are the number of glass containers assigned to each municipality on one hand and the population and the number of bars and restaurants in town on the other. The number of containers is the only discretionary input; the other two are considered non-controllable. In order to establish for each municipality a target to aim at, an aggregated-output orientation is used. That is, instead of projecting each municipality independently, a centralised approach is used. Thus, the model does not require that each municipality keeps at least the same number of containers but only that the total number of existing containers not be exceeded. The goal of the regional authority is to assign the available containers so as to maximise the total amount of glass recycled by all the municipalities. The fact that the number of containers is an integer variable has been taken into account. Numerical results are shown.Recycling operations Resource allocation Data envelopment analysis

On-line timetable re-scheduling in regional train services

In the daily activity of regional railway traffic, when the circulation frequencies are high, any anomaly that alters the scheduled circulation of trains may distort any of all of the established timetables and involve re-scheduling many of services, due to the numerous possible alternatives for resolving the situation. An on-line model is presented in this article which helps in choosing the most appropriate solution based on an intelligent exploration of the solutions space. The tool has been implemented in the Spanish national railways company.