This paper studies the Robust Coloring Problem (RCP), a variant of the Minimal Coloring Problem which maintains the number of colors fixed. In this problem, two non-adjacent vertex that have the same color are penalized. The sum of penalties of a coloring is called rigidity level. To solve the RCP, an Iterated Local Search (ILS) algorithm using the Random Variable Neighborhood Descent (RVND) lo...

Variable Neighbourhood Search (VNS) is one of the most recent metaheuristics used for problem solving in which a systematic change of neighbourhood within a local search is carried out. In this paper, an investigation on implementing VNS for job shop scheduling problems is carried out tackling benchmark suites collected from OR library. The idea is to build the best local search and shake opera...

We consider the two-echelon location-routing problem (2ELRP), a well-known problem in freight distribution arising when establishing a two-level transport system with limited capacities. The problem is a generalization of the NP-hard location routing problem (LRP), involving strategic (location), tactical (allocation) and operational (routing) decisions at the same time. We present a variable n...

in this study, an optimization model is proposed to design a global supply chain (gsc) for a medical device manufacturer under disruption in the presence of pre-existing competitors and price inelasticity of demand. therefore, static competition between the distributors’ facilities to more efficiently gain a further share in market of economic cooperation organization trade agreement (ecota) is...

In this paper, we propose a novel hybrid variable neighborhood search algorithm combining with the genetic algorithm (VNS+GA) for solving the multi-objective flexible job shop scheduling problems (FJSPs) to minimize the makespan, the total workload of all machines, and the workload of the busiest machine. Firstly, a mix of two machine assignment rules and two operation sequencing rules are deve...

We consider a location-distribution problem motivated by a case study for a multi-channel retailing company, which sells a wide variety of products via Internet, mail order catalogs, and stores. Since most items to deliver are small or medium-size parcels, consolidation is a major concern which is addressed by designing a multi-echelon distribution system. This system is adaptive, in the sense ...

Variable neighborhood search (VNS) is a metaheuristic, or framework for building heuristics, based upon systematic change of neighborhoods both in a decent phase to find a local minimum, and in a perturbation phase to get out of the corresponding valley. It was first proposed in 1997 and since has rapidly developed both in its methods and its applications. Both of these aspects are thouroughly ...

In this paper, a new fix-and-optimize (FO) approach is proposed for two dynamic multi-level capacitated lot sizing problems (MLCLSP), the MLCLSP without setup carryover and the MLCLSP with setup carryover. Given an MIP model of a lot sizing problem, the approach iteratively solves a series of subproblems of the model until no better solution can be found. Each sub-problem re-optimizes a subset ...