Claudio Bettini

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Development of context-aware applications is inherently complex. These applications adapt to changing context information: physical context, computational context, and user context/tasks. Context information is gathered from a variety of sources that differ in the quality of information they produce and that are often failure prone. The pervasive computing(More)
Since the beginning of the human effort to understand natural phenomena, the problem of measuring time and that of properly relating different time measures occupy a central position. Periodic natural events, such as the earth rotation, the alternation of lunar phases, and the earth revolution around the sun, were commonly identified as suitable time units(More)
The dynamic nature of events, in particular business processes, is a natural and accepted feature of today’s business environment. Therefore, workflow systems, if they are to successfully model portions of the real world, need to acknowledge the temporal aspect of business processes. This is particularly true for processes where any deviation from the(More)
1 Dipartimento di Scienze dell'Informazione, Universit~ degli Studi di Milano, Milano, Italy bettini@dsi, unimi, i t , http ://mercurio. sm. dsi. unimi, it/'bert ini/ 2 Department of Computer Science, James Cook University, Townsville, Australia curtis@cs, j cu. edu. au, http: I/w~z. cs. j cu. edu. au/" curt is/ 3 Department of Computer Science, University(More)
In a workflow system, autonomous agents perform various activities cooperatively to complete a common task. Successful completion of the task often depends on correct synchronization and scheduling of agents' activities. It would greatly enhance the capabilities of current workflow systems if quantitative temporal constraints on the duration of activities(More)
This paper presents a preliminary investigation on the privacy issues involved in the use of location-based services. It is argued that even if the user identity is not explicitly released to the service provider, the geo-localized history of user-requests can act as a quasi-identifier and may be used to access sensitive information about specific(More)
Access control models, such as the ones supported by commercial DBMSs, are not yet able to fully meet many application needs. An important requirement derives from the temporal dimension that permissions have in many real-world situations. Permissions are often limited in time or may hold only for specific periods of time. In this article, we present an(More)
This paper presents a general framework to define time granularity systems. We identify the main dimensions along which different systems can be characterized, and investigate the formal relationships among granularities in these systems. The paper also introduces the notion of a network of temporal constraints with (multiple) granularities emphasizing the(More)
In the recent literature on time representation, an effort has been made to characterize the notion of time granularity and the relationships between granularities. The main goals are having a common framework for their specification, and allowing the interoperability of systems adopting different time granularities. This paper considers the mathematical(More)
The purpose of good database logical design is to eliminate data redundancy and isertion and deletion anomalies. In order to achieve this objective for temporal databases, the notions of <italic>temporal types</italic>, which formalize time granularities, and <italic>temporal functional dependencies</italic> (TFDs) are intrduced. A temporal type is a(More)