Giorgio Terracina

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This paper considers the problem of reasoning on massive amounts of (possibly distributed) data. Presently, existing proposals show some limitations: (i) the quantity of data that can be handled contemporarily is limited, due to the fact that reasoning is generally carried out in main-memory; (ii) the interaction with external (and independent) DBMSs is not(More)
The task of an <i>information integration system</i> is to combine data residing at different sources, providing the user with a unified view of them, called <i>global schema.</i> Users formulate queries over the global schema, and the system suitably queries the sources, providing an answer to the user, who is not obliged to have any information about the(More)
Datalog∃ is the extension of Datalog, allowing existentially quantified variables in rule heads. This language is highly expressive and enables easy and powerful knowledge-modeling, but the presence of existentially quantified variables makes reasoning over Datalog∃ undecidable, in the general case. The results in this paper enable powerful, yet decidable(More)
This paper presents a novel approach for the integration of a set of eXtensible Markup Language (XML) Schemas. The proposed approach is specialized for XML, almost automatic, semantic and ‘‘light’’. Further, an original peculiarity is that it is parametric w.r.t. a ‘‘severity’’ level against which the integration task is performed. The paper describes the(More)
Datalog∃ is the extension of Datalog allowing existentially quantified variables in rule heads. This language is highly expressive and enables easy and powerful knowledge-modelling, but the presence of existentially quantified variables makes reasoning over Datalog∃ undecidable in the general case. Restricted classes of Datalog∃, such as Shy, have been(More)
or The abstractor is activated by the repository constructor for producing the abstracted schema associated with each global schema obtained by the integrator. The procedure it implements receives a cluster Cl and a data repository DR. It abstracts the global schema representing Cl, i.e. puts together schema objects into homogeneous groups and, for each(More)
The discovery of frequently occurring patterns in a time series could be important in several application contexts. As an example, the analysis of frequent patterns in biomedical observations could allow to perform diagnosis and/or prognosis. Moreover, the efficient discovery of frequent patterns may play an important role in several data mining tasks such(More)