Preface to the special issue “ICVNS 2018”

Abstract

The Variable Neighborhood Search (VNS) metaheuristic is based on systematic changes in the neighborhood structure within a search. It has been successfully applied for the solution of various global and combinatorial optimization problems [7]. The aim of this special issue of Journal of Global Optimization (JOGO) is to present some recent methodological developments in the field of Variable Neighborhood Search and also to publish emerging applications in this area. The VNS papers in this issue are linked to the 6th International Conference on Variable Neighborhood Search (ICVNS 2018) [8], which was held in Sithonia, Halkidiki, Greece, during October 4–7, 2018. Each submission was peer reviewed by at least two referees, according to the editorial policy of JOGO. Sixteen articles were submitted to this issue and after the refereeing process, the following six of them were finally accepted for publication: The issue begins with the paper “Improved metaheuristics for the quartet method of hierarchical clustering” authored by Consoli et al. [1]. The authors present improved metaheuristics for the quartet method of clustering, a novel hierarchical clustering approach based on the N P-hard minimum quartet tree cost problem. The second paper considers continuous location problems and it is titled “The continuous single-source capacitated multi-facility Weber problem with setup costs: formulation and solution methods”. Irawan et al. [4] introduce a new nonlinear mathematical model and efficient metaheuristic solution approaches based on Variable Neighbourhood Search. Gil-Borrás et al. [3], in the paper “GRASP with Variable Neighborhood Descent for the online order batching problem”, deal with the online order batching problem. The authors have developed a hybrid method based on the combination of a Greedy Randomized Adaptive