Ricerc@Sapienza

[No abstract available]

A significant portion of information that is nowadays collected in enterprises and organizations resides in text documents, and thus is inherently unstructured. Turning it into a structured form is the aim of information extraction (IE). Depending on the approach followed, the output of an IE process can fill forms or populate relational tables, or can be presented through an ontology.

In this paper we study the problem of information disclosure in ontology-based data access (OBDA). Following previous work on Controlled Query Evaluation, we introduce the framework of Policy-Protected OBDA (PPOBDA), which extends OBDA with data protection policies specified over the ontology and enforced through a censor, i.e., a function that alters answers to users' queries to avoid the disclosure of protected data.

In Ontology-Based Data Access (OBDA), a domain ontology is linked to the data sources of an organization in order to query, integrate and manage data through the concepts and relations of the domain of interest, thus abstracting from the structure and the implementation details of the data layer.

OWL 2 QL is the pro le of OWL 2 targeted to Ontology-Based Data Access (OBDA) scenarios, where large amount of data are to be accessed, and thus answering conjunctive queries over data is the main task. However, this task is quite restrained wrt the classical KR Ask-and-Tell framework based on querying the whole theory, not only facts (data). If we use SPARQL as query language, we get much closer to this ideal.