We present a Variable Neighborhood Search heuristic for the rolling stock rescheduling problem. Rolling is needed when disruption leads to cancellations in timetable. In rescheduling, one must then assign duties, i.e., sequences of trips, available train units such way that both passenger comfort and operational performance are taken into account. For our heuristic, we introduce three neighborh...

Given a set of elements and a symmetric matrix representing dissimilarities between them, the maximally diverse grouping problem asks to find a partitioning of the elements into a fixed number of restricted size-groups such that the sum of pairwise dissimilarities between elements in the same group is maximized. We present multistart simulated annealing, hybrid genetic and variable neighborhood...

Ant algorithms were first written about in 1991 and since then they have been applied to many problems with great success. During these years the algorithms themselves have been modified for improved performance and also been influenced by research in other fields. Since the earliest Ant algorithms, heuristics and local search have been the primary knowledge sources. This thesis asks the questi...

This paper presents a variable neighborhood search (VNS) algorithm for solving bandwidth coloring problem (BCP) and bandwidth multicoloring problem (BMCP). BCP and BMCP are generalizations of the well known vertex coloring problem and they are of a great interest from both theoretical and practical points of view. Presented VNS combines a shaking procedure which perturbs the colors for an incre...

In this work, a study on Variable Neighborhood Search algorithms for multi-depot dial-a-ride problems is presented. In dial-a-ride problems patients need to be transported from pre-specified pickup locations to pre-specified delivery locations, under different considerations. The addressed problem presents several constraints and features, such as heterogeneous vehicles, distributed in differen...