1,720,970 research outputs found
Weakening Non-Interference on Databases
No full textOur aim is to exploit this semantic characterization of security policies for certifying the security level of a given multilevel secure database from different points of view following the ideas proposed for ANI in language-based security
Temporal Functional dependencies with multiple granularities: a logic based approach
No full textFunctional dependencies allow one to define semantic constraints on relational database schemata; even though functional dependencies do not focus on data dynamics, some efforts have been devoted in these last twenty years to extend functional dependencies to support temporal aspects of data. Different temporal functional dependencies have been proposed, which capture temporal features which are slightly different one from each other. In this paper we propose a logic based approach for the problem of modeling and managing temporal data dependencies. More particularly, we show how our proposal allows one to express in a homogeneous way the temporal functional dependencies previously proposed in the literature
Merging Multimedia Presentations and Semistructured Temporal Data: a Graph-based Model and its Application to Clinical Information
No full textSemistructured data are data having some structure, that may be irregular or incomplete and does not necessarily conform to a fixed schema. Semistructured data often contain the description of histories of the considered real world. The eXtensible Markup Language (XML) is becoming a cross compatible and standardized means for representing semistructured clinical data. In the field of medical informatics, there are many ongoing activities concerning XML. In the field of multimedia database systems, the topic related to the integration of several media objects (with their temporal aspects) have been considered both for data modeling and querying issues and for modeling multimedia presentations.
In this paper, we focus on the issue of providing physicians with the capability of representing in a seamless way both temporal aspects of multimedia semistructured data and their temporal presentation requirements
A semistructured data model for multimedia and temporal clinical information
No full textIn this paper, we propose a semistructured data model for multimedia and temporal clinical information. Our Multimedia Temporal Graphical Model (MTGM) allows one to represent and store clinical information in a semistructured, temporal, and multimedia database. Moreover, the physician can define multimedia presentations based on the stored data. Multimedia presentations are then stored in the same MTGM database together with clinical information and are thus represented according to the same data model. We focus on the issue of providing physicians with the capability of representing in a seamless way both temporal aspects of multimedia data and their temporal presentation requirements. In this context, the valid time is associated both to semistructured information and to multimedia presentations. Furthermore, synchronization constraints can be specified for multimedia presentations. Motivations for our proposal are provided, taken from the domain of cardiac angiography. Taking into account the most recent web-related technologies, we deal also with the translation of MTGM presentations into XML and SMIL documents
Towards association rules for XML documents
Full text linkIn this work we propose a flexible approach to extract and evaluate association rules on XML documents. We describe two kinds of association rules: structural associations and value associations. A structural association allows one to capture the similarity of an XML document with respect to a given structure, while a value association allows one to capture the similarity of the information contained in the XML document with respect to a given scenario. Moreover, we show how it possible to compose these associations in order to describe complex association rules on XML documents
A Uniform Algebraic Characterization of Temporal Functional Dependencies
No full textIn the database literature, different types of temporal functional dependencies (TFDs) have been proposed to constrain the temporal evolution of information. Unfortunately, the lack of a common notation makes it difficult to compare, to integrate, and to possibly extend the various proposals. In this paper, we outline a unifying algebraic framework for TFDs. We first introduce the proposed approach, then we use it to give a uniform account of existing TFDs, and finally we show that it allows one to easily express new meaningful TFDs
Using context for the extraction of relational views
No full textThe paper presents an approach for automatically extracting views from a relational database schema, based on the knowledge of the application domain. In order to achieve such result, the possible contexts emerging from the application domain are identified and, starting from the representation of the characterizing dimensions, a sequence of operations is applied to the schema to derive the portion of interest or, as we say, to tailor the schema with respect to each possible context. We introduce the tailoring operators as well as the method to compose partial views to obtain the final ones; a running example is used to lead the reader through the steps of the proposed methodology
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