Apercu sur les quadarbres et les structures de donnees hierarchiques. Elles sont basees sur le principe de decomposition recursive. L'accentuation est mise sur la representation de donnees dans les applications de traitement d'images, d'infographie, les systemes d'informations geographiques et la robotique. On examine en detail un certain nombre d'operations dans lesquelles de telles structures de donnees trouvent leur utilisation

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The Quadtree and Related Hierarchical Data Structures

Hawaii International Conference on System Sciences

Extending and implementing the stable model semantics

One distinctive feature of any adaptive system is the user model that represents essential information about each user This chapter complements other chapters of this book in reviewing user models and user modeling approaches applied in adaptive Web systems The presentation is structured along three dimensions: what is being modeled, how it is modeled, and how the models are maintained After a broad overview of the nature of the information presented in these various user models, the chapter focuses on two groups of approaches to user model representation and maintenance: the overlay approach to user model representation and the uncertainty-based approach to user modeling

User models for adaptive hypermedia and adaptive educational systems

Product family design and platform-based product development has received much attention over the last decade. This paper provides a comprehensive review of the state-of-the-art research in this field. A decision framework is introduced to reveal a holistic view of product family design and platform-based product development, encompassing both front-end and back-end issues. The review is organized according to various topics in relation to product families, including fundamental issues and definitions, product portfolio and product family positioning, platform-based product family design, manufacturing and production, as well as supply chain management. Major challenges and future research directions are also discussed.

Product family design and platform-based product development: a state-of-the-art review

This article presents a generalized ontology of product configuration as a step towards a general ontology of configuration, which is needed to reuse and share configuration knowledge. The ontology presented consists of a set of concepts for representing the knowledge on a configuration and the restrictions on possible configurations. The ontology is based on a synthesis of the main approaches to configuration. Earlier approaches are extended with new concepts arising from our practical experience on configurable products. The concepts include components, attributes, resources, ports, contexts, functions, constraints, and relations between these. The main contributions of this work are in the detailed conceptualization of knowledge on product structures and in extending the resource concept with contexts for limiting the availability and use of resources. In addition, constraint sets representing different views on the product are introduced. The ontology is compared with the previous work on configuration. It covers all the principal approaches, that is, connection-based, structure-based, resource-based, and function-based approaches to configuration. The dependencies between the concepts arising from different conceptualizations are briefly analyzed. Several ways in which the ontology could be extended are pointed out.

Towards a general ontology of configuration

The design and production of goods that satisfy the special needs of individual customers are of central interest to the European industry. A major trend is to improve customer specific adaptation with configurable products. We are interested in the methods, practices and tools that support product configuration tasks. The research described in this paper is meant to guide our future work. We have 1) established a framework for understanding the problem area of product configuration in a fairly wide sense by identifying a number of factors and 2) carried out ten actual case studies using the proposed framework.

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State-of-the-practice in product configuration — a survey of 10 cases in the Finnish industry

This paper aims at identifying critical factors affecting organization-wide implementation of requirements engineering (RE) processes. The paper is based on a broad literature review and three longitudinal case studies that were carried out using an action research method. The results indicate that RE process implementation is a demanding undertaking, and its success greatly depends on such human factors as motivation, commitment and enthusiasm. Therefore, it is essential that the RE process is useful for its individual users. Furthermore, the results indicate that organizations can gain benefits from RE by defining a simple RE process, by focusing on a small set of RE practices, and by supporting the systematic usage of these practices. q 2004 Elsevier B.V. All rights reserved.

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Implementing requirements engineering processes throughout organizations: success factors and challenges

Industrial companies need powerful data modelling mechanisms, e.g. classification, for the description of their products. The companies that adapt their products to the needs of individual customers in a routine manner have perhaps the most urgent needs. They must efficiently describe large numbers of product variants. STEP Application Protocol 214 (AP 214) for the automotive industry also addresses the modelling of product variants, i.e. generic product structure modelling. In addition to AP 214, the same mechanisms are needed in other standardization efforts as well, e.g. STEPlib of AP 221 and PLIB. STEP, however, does not include a mechanism for using classification and inheritance for modelling products of an individual company. These facilities are included in EXPRESS, but EXPRESS can only be used for describing the data schema to be standardized. The fundamental structure of STEP, therefore, prohibits a company from modelling its products in an object-oriented manner. This is an issue that may seriously affect the future of STEP as a general product-modelling methodology. The problems and possibilities of extending STEP in this direction within its current structure are discussed and a new mechanism is outlined as an alternative solution.

Modelling generic product structures in STEP

The paper demonstrates that product configuration applications fit naturally the framework of answer set programming. It is shown that product configuration knowledge can be represented systematically and compactly using a logic program type rule language such that the answers of a configuration task, the configurations, correspond to the models of the rule representation.. The paper pr.es.~nts such a"}ule-bised forrealization of a unified configuration oni~o]ogy using a" weight constraint rule language. The language extends normal logic programs with cardinality and weight constraints which leads to a compact and simple formalization. The complexity of the configuration task defined by the formalization is shown to be NP-complete.

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Reijo Sulonen

Papers

Towards a general ontology of configuration

State-of-the-practice in product configuration — a survey of 10 cases in the Finnish industry

Implementing requirements engineering processes throughout organizations: success factors and challenges

Modelling generic product structures in STEP

Representing Configuration Knowledge With Weight Constraint Rules