On Data Management in Pervasive Computing Environments

Abstract—This paper presents a framework to address new data management challenges introduced by data-intensive, pervasive computing environments. These challenges include a spatio-temporal variation of data and data source availability, lack of a global catalog and schema, and no guarantee of reconnection among peers due to the serendipitous nature of the environment. An important aspect of our solution is to treat devices as semiautonomous peers guided in their interactions by profiles and context. The profiles are grounded in a semantically rich language and represent information about users, devices, and data described in terms of “beliefs,” “desires, ” and “intentions. ” We present a prototype implementation of this framework over combined Bluetooth and Ad Hoc 802.11 networks and present experimental and simulation results that validate our approach and measure system performance. Index Terms—Mobile data management, pervasive computing environments, data and knowledge representation, profile-driven caching algorithm, profile driven data management, data-centric routing algorithm. æ

Selecting tense, aspect, and connecting words in language generation

Generating language that reflects the temporal organization of represented knowledge requires a language generation model that integrates contemporary theories of tense and aspect, temporal representations, and methods to plan text. This paper presents a model that produces complex sentences that reflect temporal relations present in underlying temporal concepts. The main result of this work is the successful application of constrained linguistic theories of tense and aspect to a generator which produces meaningful event combinations and selects appropriate connecting words that relate them

Qualified Answers That Reflect User Needs and Preferences

This paper introduces a formalism to describe the needs and preferences of database users. Because of the precise formulation of these concepts, we have found an automatic and very simple mechanism to incorporate user needs and preferences into the query answering process. In the formalism, the user provides a lattice of domain independent values that define preferences and needs and a set of domain specific user constraints qualified with lattice values. The constraints are automatically incorporated into a relational or deductive database through a series of syntactic transformations that produces an annotated deductive database. Query answering procedures for deductive databases are then used, with minor modifications, to obtain annotated answers to queries. Because preference declaration is separated from data representation and management, preferences can be easily altered without touching the database. Also, the query language allows users to ask for answers at different prefere..

Uma ontologia para expressão de preferências de utilizadores em sistemas OLAP

Dissertação de mestrado em Informática (área de especialização em Sistemas de Suporte à Decisão)Na maioria dos casos em que se submete uma query a um sistema, recebemos uma “enxurrada” de dados como resposta, que em grande parte não nos interessa. Na realidade, ao se obter um qualquer record set, fazemos frequentemente uma forte triagem para que fiquemos apenas com aquilo que realmente nos interessa no âmbito do problema que temos em mãos. De facto, era muito útil que, de algum modo, fosse possível expressar as nossas preferências em termos daquilo que queremos obter aquando do lançamento de uma dada query. Diversas pesquisas têm sido feitas com o objectivo de conseguir expressar as preferências dos utilizadores, no sentido de apresentar resultados mais satisfatórios nas suas consultas, mais próximos daquilo que o utilizador pretende. As preferências são utilizadas como filtragem nas consultas efectuadas, com o objetivo de reduzir o volume de dados que potencialmente poderá ser apresentado ao utilizador. Estas ajudam, também, na criação de políticas com base nos perfis dos utilizadores. Assim, neste trabalho de dissertação é proposto estudar a possibilidade de melhorar a interação dos utilizadores com os sistemas OLAP, recorrendo para isso à Web Semântica, nomeadamente à utilização de um modelo ontológico e a técnicas mais avançadas de expressão de preferências.In most cases in which a query is submitted to a system, the response is a “flood” of data which largely does not have any interest to us. Actually, to obtain any record set, we often do a strong triage to obtain what really interests us in the scope of the problem that we currently have. In fact, it would be very helpful that, somehow, we had the possibility to express our preferences in terms of what we want to get at the launch of a given query. Several researches have been done with the purpose of getting the user preferences expressed, in order to provide a more satisfactory result of the queries, closer to what the user pretends. User preferences are used as a filter in the result set, with the aim of reducing the data volume that could, potentially, be presented to the user. They help, also, in creating policies based on user profiles. Thus, in this dissertation work, it is proposed to study the possibility of improving the interaction of users with OLAP systems, resorting to Semantic Web, in particular the use of an ontological model and the most advanced techniques of expression of preferences