1,720,994 research outputs found
Introducing cooperation and actions in amalgamated knowledge bases
No full textThe theory of amalgamated knowledge bases represents a formal logical foundation for heterogeneous databases. In an amalgamated knowledge base, data sources are modeled by generalized annotated logic. Moreover, an amalgamated knowledge base is equipped with a supervisor acting as a mediator for amalgamating knowledge from the local databases. Even if the framework is quite appealing, it does not model dynamic aspects. Moreover, no communication channels among local databases are supported and cooperation is provided only through the supervisor. In this paper, we extend the theory of amalgamated knowledge bases to deal with actions and cooperation among local database
Introducing dynamic behavior in amalgamated knowledge bases
No full textThe problem of integrating knowledge from multiple and heterogeneous sources is a fundamental issue in current information systems. To cope with this problem, the concept of mediator has been introduced as a software component providing intermediate services, linking data resources and application programs, and making transparent the heterogeneity of the underlying systems. In designing a mediator architecture, we believe that an important aspect is the definition of a formal framework by which one is able to model integration according to a declarative style. To this purpose, the use of a logical approach seems very promising. Another important aspect is the ability to model both static integration aspects, concerning query execution, and dynamic ones, concerning data updates and their propagation among the various data sources. Unfortunately, as far as we know, no formal proposals for logically modeling mediator architectures both from a static and dynamic point of view have already been developed. In this paper, we extend the framework for amalgamated knowledge bases, presented in Subrahmanian (1994), to deal with dynamic aspects. The language we propose is based on the Active U-Datalog language (Bertino et al., 1998), and extends it with annotated logic and amalgamation concepts from Kifer and Subrahmanian (1992) and Subrahmanian (1987). We model the sources of information and the mediator (also called supervisor) as Active U-Datalog deductive databases, thus modeling queries, transactions, and active rules, interpreted according to the PARK semantics (Gottlob et al., 1996). By using active rules, the system can efficiently perform update propagation among different databases. The result is a logical environment, integrating active and deductive rules, to perform queries and update propagation in an heterogeneous mediated framework
Making the analysis of the Italian legislative system easy : the ILMA web portal
Full text linkThe Italian Law-Making Archive, denoted ILMA, is a new web application for supporting the analysis of the Italian legislative processes. It aims to overcome the shortcomings that commonly affect quantitative analyses of legislative systems providing ready-to-use data on the Italian context organized in a relational structure and included in a unique repository. After having compared ILMA with other web information systems, the article describes the database architecture, proposes several examples of potential customized analyses that scholars may conduct through ILMA and, finally, explains its main functionalities for querying the database and exporting data
On comparing the expressing power of access control model frameworks
No full textOne of the key requirements of an Adaptive Security Infrastructure (ASI) is the ability of formally reasoning about the specified security policies. In this paper, we contribute to this issue by focusing on one of the most relevant kind of security policies, i.e., access control policies. Several access control frameworks have been proposed so far in the literature, based on different formalisms. However, what has not yet so far extensively explored is the comparison of the expressive power of such frameworks. We believe that this is a key issue since such analysis can be the basis for choosing the framework that better fits the security needs of a given domain. This analysis is particular relevant for complex and distributed environments, like the ones in which the ASI paradigm may be usefully applied. The aim of this paper is thus to make a step in this direction by comparing the expressive power of three well known frameworks with respect to the set of access control models they are able to express
Managing intellectual property in a music fruition environment
No full textWith the advent of the digital age and the spread of portable digital audio players, interest in software and hardware tools that can help producers and distributors enhance and revive their catalogue of music has progressively increased. One of the main concerns of major labels is how to prevent file sharing. An innovative approach that couples reviving catalogues with support for rights management could provide an experience of multimedia content in which users select multiple media streams on the fly in a fully synchronized environment. Because this kind of user experience can't be reconstructed from the single original streams, illegal copying would be intrinsically discouraged. In this article, the authors propose an approach to encode contents and build advanced multimodal interfaces that protect intellectual property. As a case study, they use the IEEE 1599--an international standard for music description
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