Piero A. Bonatti

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Role-based access control (RBAC) models are receiving increasing attention as a generalized approach to access control. Roles may be available to users at certain time periods, and unavailable at others. Moreover, there can be temporal dependencies among roles. To tackle such dynamic aspects, we introduce Temporal-RBAC (TRBAC), an extension of the RBAC(More)
The widespread use of Internet-based services is increasing the amount of information (such as user pro les) that clients are required to disclose. This information demand is necessary for regulating access to services, and functionally convenient (e.g., to support service customization), but it has raised privacy-related concerns which, if not addressed,(More)
As fragments of first-order logic, Description logics (DLs) do not provide nonmonotonic features such as defeasible inheritance and default rules. Since many applications would benefit from the availability of such features, several families of nonmonotonic DLs have been developed that are mostly based on default logic and autoepistemic logic. In this(More)
Despite considerable advancements in the area of access control and authorization languages, current approaches to enforcing access control are all based on monolithic and complete specifications. This assumption is too restrictive when access control restrictions to be enforced come from the combination of different policy specifications, each possibly(More)
We introduce the provisional trust negotiation framework PROTUNE, for combining distributed trust management policies with provisional-style business rules and access-control related actions. The framework features a powerful declarative metalanguage for driving some critical negotiation decisions, and integrity constraints for monitoring negotiations and(More)
The need to automatically extract and classify the contents of multimedia data archives such as images, video, and text documents has led to significant work on similarity based retrieval of data. To date, most work in this area has focused on the creation of index structures for similarity based retrieval. There is very little work on developing formalisms(More)
A uniform proof-theoretic reconstruction of the major nonmonotonic logics is introduced. It consists of analytic sequent calculi where the details of nonmonotonic assumption making are modelled by an axiomatic rejection method. Another distinctive feature of the calculi is the use of provability constraints that make reasoning largely independent of any(More)
While many works have been devoted to service matchmaking and modeling nonfunctional properties, the problem of matching service requests to offers in an optimal way has not yet been extensively studied. In this paper we formalize three kinds of optimal service selection problems, based on different criteria. Then we study their complexity and implement(More)