Abstract
One major practical problem when applying traditional metaheuristics seems to be their strong dependency on parameter tuning. This issue is frequently pointed out as a major shortcoming of metaheuristics and is often a reason for Decision-Makers to reject using this type of approach in practical situations. In this paper we present a new search strategy - Constraint Oriented Neighbourhoods - that tries to overcome the referred drawback. The aim is to control the grade of randomness of metaheuristics, by defining "special" neighbourhood movements, that lead to a more robust heuristic, less dependent on parameter tuning. This is achieved by selecting and applying particular movements that take into account the potential violation of problem constraints. The strategy is illustrated in a real problem arising in the area of Power Systems Management - the Unit Commitment Problem, the computational experiments on a set of problem instances systematically outperforming those presented in the literature, both in terms of efficiency, quality of the solution and robustness of the algorithm.

Abstract
Collaborative Networks (CN) and Virtual Organisations (VO) can partially be modelled by using Graph Theory, as a natural framework for describing relationships, interactions and collaboration. Our work aims at extending and integrating results from that theory and other different fields and scientific disciplines, to enable modelling complex and non tangible factors, dynamics, trade-offs between individual and common objectives, arising in the set-up and management of VO. As a way to handle these issues in a holistic way, we present extensions of Social Actors Networks that are able to encompass various, complementary perspectives in dealing with VO, and coping with the different phases of its life cycle. Current results seem promising in the direction of creating a sound frame work for modelling and supporting holistic process management in Collaborative Networks. For illustration purposes a simple case study is briefly sketched and some findings presented. Finally sortie open issues are surveyed and lines for future research identified.

Abstract
This paper describes a study of planning vehicle routes for the collection of urban recyclable waste. The aim is to create collection routes for every day of the month, to be repeated every month, minimizing the operation cost. Two important features of the problem are the planning of a relatively long period of time and the separate collection of three types of waste. The collection operation was modelled in accordance to the practice of the company that manages the collection system. Heuristic techniques were developed to solve the model in three phases: definition of the geographic zones served by the vehicles, definition of the waste type to collect on each day of the month, definition of the collection routes. Preliminary results suggest that significant economies in collection costs are possible.

Abstract
This work describes a real-world industrial problem of production planning and cutting optimization of reels and sheets, occurring at a Portuguese paper mill. It will focus on a particular module of the global problem, which is concerned with the determination of the width combinations of the items involved in the planning process: the main goal consists in satisfying an order set of reels and sheets that must be cut from master reels. The width combination process will determine the quantity/weight of the master reels to be produced and their cutting patterns, in order to minimize waste, while satisfying production orders. A two-phase approach has been devised, naturally dependent on the technological process involved. Details of the models and solution methods are presented. Moreover some illustrative computational results are included.

Abstract
There is an increasing interest in exploring the opportunities for competitive advantage that arise from reinforcing core competencies and innovative capabilities of the individual companies, and by forming integrated supply networks. In complex and dynamic environments such as the automotive and semiconductor industries, managing and co-ordinating the procurement of materials, their transformation into intermediate and finished products, and the distribution to the final customers, are very demanding tasks in terms of information systems. In general, current available software packages do not provide the full support needed for networked and distributed organizations, and are clearly insufficient in what concerns the planning and coordination activities needed in these heterogeneous environments. In order to adequately tackle these problems, this work proposes a multi-agent system architecture for real-time customer-order planning in distributed manufacturing enterprises, addressing the requirements of a make-to-order environment. The present research work resulted from the Co-OPERATE European Project. Enhanced visibility of information, early warning of disturbances, synchronized production and collaborative planning in the supply chain are the general goals of the project. In particular, for aggregate planning and order promising, a distributed and decentralized information system, based on an architecture of agents and extensively using the internet, was designed and implemented. This system aims at responding to the basic requirements of cooperativeness, integration and configurability, and at providing new and more powerful decision support.

Abstract
A large variety of techniques have been developed to solve or approximate the solution of multiattribute ranking problems. From such techniques, several implicit or explicit partial orders, defined on the same set of alternatives, are obtained (in many cases, by pairwise comparisons) with the goal of determining a linear order. Often, this goal is attained by assigning positive weights to each partial order relation. However, the imprecise judgments of the pairwise comparisons as well as other factors lead to inconsistencies which have been analyzed in an extensive literature devoted to this type of problem. In this paper, numerical results about linear extensions of weighted sum relations are applied to the recognition of pairwise imprecise judgments between alternatives as well as to the confirmation of a ranking solution as a linear extension of a quasi-order defined by a weighted sum of binary preference relations. (C) 2003 Wiley Periodicals, Inc.