Resumo em Inglês:

This paper describes a control mechanism for dynamic selection of Quality of Service (QoS) parameters used in a IEEE 802.11e Wireless Local Area Network (WLAN). The 802.11e specification, still under development, provides a new contention-based access method, called Enhanced Distributed Coordination Function (EDCF). This method uses distinct values for interframe space and for contention window size to establish priorities between Access Categories (ACs). The proposed mechanism selects these values based on the actual network load condition and on the applications delay requirements. Such mechanism improves the new QoS functionality, aiming to promote better channel utilization as well as to keep the desired service levels.

Resumo em Inglês:

We present a technique to prove invariants of model-based specifications in a fragment of set theory. Proof obligations containing set theory constructs are translated to first-order logic with equality augmented with (an extension of) the theory of arrays with extensionality. The idea underlying the translation is that sets are represented by their characteristic function which, in turn, is encoded by an array of Booleans indexed on the elements of the set. A theorem proving procedure automating the verification of the proof obligations obtained by the translation is described. Furthermore, we discuss how a sub-formula can be extracted from a failed proof attempt and used by a model finder to build a counter-example. To be concrete, we use a B specification of a simple process scheduler on which we illustrate our technique.

Resumo em Inglês:

In Educational literature, Discovery Learning appears as an approach in which the learner builds up his/her own knowledge by performing experiments within a domain and inferring/increasing rules as a result. Such a constructivist approach has been largely exploited in the design of computational artefacts with learning purposes, the so-called Discovery Learning Environments (DLEs). One known feature of such environments is the autonomy degree required for students to succeed while handling a domain. Additionally, DLEs designers are often challenged to get students actually engaged. Such questions are on the basis of our concerns with the design and usage of particular DLEs, within which learning events occur as a consequence of contradiction detection and overcoming, during human/machine cooperative work. In this paper, we present an artificial agent capable of handling such a contradiction-driven approach of learning, by highlighting the exchanges that the agent should promote with a human learner. The conceptual model supporting the agent's design relies on the scientific rationale, particularly the empirical approach guided by the theory-experiment confrontation. We shall reinforce the interest of the model for the design of DLEs by presenting its exploitation in a real learning situation in Law. Also, we suggest potential instantiations of the model elsewhere than in Human Learning.

Resumo em Inglês:

Ontologies are becoming an important mechanism to build information systems. However, ontology construction is not a simple task. So, it is necessary to provide tools that support ontology development. This paper presents ODEd, an ontology editor that supports the definition of concepts, relations and properties, using graphic representations, besides promoting automatic inclusion of some classes of axioms and derivation of object infrastructures from ontologies. ODEd was built to support ontology development in ODE, a software engineering environment (SEE), so that ODE can be used as a domain-oriented SEE. Thus, ODEd aims to partially support an ontology-based domain engineering process.

Resumo em Inglês:

The most basic questions that researchers must address when introducing a new process or technique are what is the intended effect of that process and can that effect be demonstrated empirically. As the understanding of a process progresses, researchers become interested in more sophisticated questions about a process or technique, such as studying the relationship between a particular type of variable and the outcome of the process. Quite often, researchers will find few, if any, studies in the literaturethat explicitly identify and analyze the effects of potential variables on the process. This paper proposes a methodology to aid in performing a literature search to be used as a basis for new research into these types of variables. The methodology provides guidance on making use of a large range of studies from which to extract potential variables. Throughout the paper, the methodology is illustrated with a specific example. The example focuses on searching for variables that deal with the individual variations among software inspectors that affect their performance during an inspection. At the end of the example, after following the steps of the methodology, a list of potential variables among software inspectors is identified. The paper concludes with the next steps to be taken concerning the identified variables and hypotheses.