Papers by Domenico Carbotta
Sebd, 2007
When relational data have access constraints that require certain attributes to be selected in qu... more When relational data have access constraints that require certain attributes to be selected in queries, as in the case of (wrapped) Web sources accessible via forms, a recursive query plan is needed to answer queries at best. We present a query plan optimisation technique for several classes of queries that minimises the number of accesses according to a novel, strong notion of minimality. We provide experimental evidence of the effectiveness of our technique.
When relational data have access constraints that require certain at- tributes to be selected in ... more When relational data have access constraints that require certain at- tributes to be selected in queries, as in the case of (wrapped) Web sources ac- cessible via forms, a recursive query plan is needed to answer queries at best. We present a query plan optimisation technique for several classes of queries that minimises the number of accesses according to a novel, strong notion of mini- mality. We provide experimental evidence of the effectiveness of our technique.
Lecture Notes in Computer Science, 2007
Relational database (DB) management systems provide the standard means for structuring and queryi... more Relational database (DB) management systems provide the standard means for structuring and querying large amounts of data. However, to access such data the exact structure of the DB must be know, and such a structure might be far from the conceptualization of a human being of the stored information. Ontologies help to bridge this gap, by providing a high level conceptual view of the information stored in a DB in a cognitively more natural way. Even in this setting, casual end users might not be familiar with the formal languages required to query ontologies. In this paper we address this issue and study the problem of ontology-based data access by means of natural language questions instead of queries expressed in some formal language. Specifically, we analyze how complex real life questions are and how far from the query languages accepted by ontology-based data access systems, how we can obtain the formal query representing a given natural language question, and how can we handle those questions which are too complex wrt the accepted query language. This research has been partially supported by FET project TONES (Thinking ON-tologiES), funded within the EU 6th Framework Programme under contract FP6-7603.
emcl-study.eu
Abstract In this work we describe the theoretical foundations and the implementation of a new aut... more Abstract In this work we describe the theoretical foundations and the implementation of a new automata-based technique for reasoning over expressive Description Logics that is worst-case optimal and lends itself to an efficient implementation. In order to show the feasibility of the approach, we have realized a working prototype of a reasoner based upon these techniques. An experimental evaluation of this prototype shows encouraging results.
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Papers by Domenico Carbotta