A VNS-based heuristic using both a facility as well as a customer type neighbourhood structure is proposed to solve the p-centre problem in the continuous space. Simple but effective enhancements to the original Elzinga-Hearn algorithm as well as a powerful ‘locate-allocate’ local search used within VNS are proposed. In addition, efficient implementations in both neighbourhood structures are pr...

The Capacitated Centred Clustering Problem (CCCP) consists in partitioning a set of n points into p disjoint clusters with a known capacity. Each cluster is specified by a centroid. The objective is to minimize the total dissimilarity within each cluster, such that a given capacity limit of the cluster is not exceeded. This paper presents a solution procedure for the CCCP, using the hybrid meta...

We propose to use local search algorithms to produce sat instances which are harder to solve than randomly generated k-cnf formulae. The first results, obtained with rudimentary search algorithms, show that the approach deserves further study. It could be used as a test of robustness for sat solvers, and could help to investigate how branching heuristics, learning strategies, and other aspects ...

This work addresses the Vehicle Routing Problem with Simultaneous Pickup and Delivery (VRPSPD). Due to its complexity, we propose a heuristic algorithm for solving it, so-called GENVNS-TS-CL-PR. This algorithm combines the heuristic procedures Cheapest Insertion, Cheapest Insertion with multiple routes, GENIUS, Variable Neighborhood Search (VNS), Variable Neighborhood Descent (VND), Tabu Search...

Article history: Received 12 October 2010 Received in revised form 20 March 2011 Accepted 21 March 2011 Available online 24 March 2011

The ability to express “derived predicates” in the formalization of a planning domain is both practically and theoretically important. In this paper, we propose an approach to planning with derived predicates where the search space consists of “Rule-Action Graphs”, particular graphs of actions and rules representing derived predicates. We present some techniques for representing rules and reaso...

It is well known that the performance of a stochastic local search procedure depends upon the setting of its noise parameter, and that the optimal setting varies with the problem distribution. It is therefore desirable to develop general priniciples for tuning the procedures. We present two statistical measures of the local search process that allow one to quickly find the optimal noise setting...

The Periodic Mobile Piston Pump Unit Routing Problem consists of, given a set of surface oil wells scattered over an onshore producing field, determining routes for each day of work, with limited duration work shift, that maximize the collection of oil carried by a mobile piston pump unit. This paper presents different construction and local search methods used in the composition of GRASP and I...

In the study of heuristics for combinatorial problems, it is often important to develop and compare, in a systematic way, different algorithms, strategies, and parameters for the same problem. This comparison is often biased not only by different implementation languages, but also by different architectures. This paper proposes a framework, described using design patterns, modeling different as...

Motivated by a problem in the theory of randomized search heuristics, we give a very precise analysis for the coupon collector problem where the collector starts with a random set of coupons (chosen uniformly from all sets). We show that the expected number of rounds until we have a coupon of each type is nHn/2 − 1/2± o(1), where Hn/2 denotes the (n/2)th harmonic number when n is even, and Hn/2...