We consider the fuzzy job shop problem, where uncertain durations are modelled as fuzzy numbers and the objective is to minimise the expected makespan. A recent local search method from the literature has proved to be very competitive when used in combination with a genetic algorithm, but at the expense of a high computational cost. Our aim is to improve its efficiency with an alternative resch...

Stochastic local search (SLS) has been an active field of research in the last few years, with new techniques and procedures being developed at an astonishing rate. SLS has been traditionally associated with satisfiability solving, that is, finding a solution for a given problem instance, as their intrinsic nature does not address unsatisfiable problems. Unsatisfiable instances were therefore c...

Many combinatorial (optimisation) problems have natural models based on, or including, set variables and set constraints. This modelling device has been around for quite some time in the constraint programming area, and proved its usefulness in many applications. This paper introduces set variables and set constraints also in the local search area. It presents a way of representing set variable...

Differently from other search paradigms (e.g., branch & bound) no widely-accepted software tool is available up to now for local search; but only a few research-level prototypes have gained limited popularity. In our opinion, the reason for this lack is twofold: On the one hand, the apparent simplicity of local search induces the users to build their applications from scratch. On the other hand...

This paper describes a tabu search heuristic with path relinking for the vehicle routing problem. Tabu search is a local search method that explores the solution space more thoroughly than other local search based methods by overcoming local optima. Path relinking is a method to integrate intensification and diversification in the search. It explores paths that connect previously found elite so...

We discuss a new algorithm based on a network measure, local betweenness centrality (LBC), for search in complex networks that are heterogeneous in node degree and edge weights. LBC search utilizes both the heterogeneities and performs the best in scale-free weighted networks. We further argue that the amount of information used by LBC search could be optimal.

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The capacitated vehicle routing problem with sequence-based pallet loading and axle weight constraints is an extension of the classical Capacitated Vehicle Routing Problem (CVRP). It integrates loading constraints in a routing problem and is based on a real-world transportation problem. The demand of the customers consists of pallets. These pallets may be placed in two horizontal rows inside th...