Abstract in English:

Requirements Engineering has been considered a key activity in any Software Engineering process. It is well known that a requirements specification should include not only software specifications but also business models and other kinds of information describing the context in which the intended system will function. In recent years we have observed a growing influence of the object-orientation paradigm. Unfortunately, the current dominant object oriented modeling technique, i.e. Unified Modeling Technique, is ill equipped for modeling early requirements which are typically informal and often focus on Organizational objectives. UML is more suitable for later phases of requirements capture, which usually focus on completeness, consistency, and automated verification of functional requirements for the new system. In this paper, we present some guidelines for the integration of early and late requirements specifications. For the organizational modeling we use the i* framework, which focuses on the description of organizational relationships among various organizational actors, as well as an understanding of the rationale for the alternatives chosen. For the functional requirements specification, we rely on a precise subset of the Unified Modeling Language annotated with constraints described in the Object Constraint Language. A small example is used to illustrate how the requirements process iterates between the early and late requirements specification.

Abstract in English:

This paper describes a unified framework for the problems of modelling and processing spatial entities. We propose a general definition of spatial objects, and show that the different types of spatial data can be expressed as particular cases of this definition. Furthermore, we present a taxonomy for the various types of GIS operations, defined in terms of the properties of this definition. Our goal is to argue that GIS data types and operations can be defined based on a single formal notion, which encapsulates the GIS concepts of both continuous fields and discrete features, with important consequences for system and interface design, interoperabilty issues and language proposal.

Abstract in English:

The concept of affordance has been brought to HCI by Don Norman, who has recently protested against its misuse by designers. They say they will put affordances in the interface, or afford this or that to the users, but Norman points out that affordances only exist inasmuch as they are perceived by users. Therefore, it doesn’t make sense to use the term as designers do. This paper takes the designers’ phrases as a spontaneous expression of design intent and explores the correspondences between these and two of the phenomena captured by communicability evaluation: missing and declining affordances. It highlights some useful distinctions between levels of affordances, and hints at possible links between communicative and cognitive perspectives. It suggests that framing affordances within a broader communicative dimension, and taking advantage of the rhetoric that people use to describe what they are doing, can bring interesting insights to design.

Abstract in English:

The solution of the mining association rules problem in customer transactions was introduced by Agrawal, Imielinski and Swami in 1993. Their approach was extended in several directions such as adding or replacing the confidence and support by other measures, or how to also account for quantitative attributes. In this paper we present an algorithm that can be used in the context of several of the extensions provided in the literature while preserving its performance, as illustrated by a case study. Our approach is targeted at two of the most computationally demanding phases in the process of generating association rules: the enumeration of the candidate sets and the verification of which of them are frequent. The minimization of the cost of these phases is achieved by pruning early candidate sets based on additional quantitative information about the transactions. In summary, we explore certain multidimensional properties of the data allowing us to combine this additional information as a pruning criterion. Based on synthetically generated data, our strategy reduced the number of candidate sets examined by the algorithm up to 15%. Furthermore, it also reduced the execution time significantly, in the order of 23%.

Abstract in English:

This paper proposes a service for multicast video distribution based on the active network paradigm. Active nodes can provide soft-state and perform customized computations on a per-user or per-application basis. These functionalities allow the deployment of an efficient and flexible service that can dynamically adjusts itself to the bandwidth availability. The source learns about the best transmission rate of the video by receiving feedback messages from receivers.A fusion mechanism is used to prevent feedback-message implosion.Simulation results show that a capsule filtering level of 96% can be achieved by using the fusion mechanism.