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Common to all aCtors in today's information world is the problem of lowering the " information noise, " both reducing the amount of data to be stored and accessed, and enhancing the " precision " according to which the available data fit the application requirements. Thus, fitting data to the application needs is tantamount to fitting a dress to a person,(More)
Independent, heterogeneous, distributed, sometimes transient and mobile data sources produce an enormous amount of information that should be semantically integrated and filtered, or, as we say, tailored, based on the user’s interests and context. Since both the user and the data sources can be mobile, and the communication might be unreliable, caching(More)
Informatics is a relatively young field within science and engineering. Its research and development methodologies build on the scientific and design methodologies in the classical areas, often with new elements to it. We take an in-depth look at one of the less well-understood methodologies in infor-matics, namely experimentation. What does it mean to do(More)
In the present global society, information has to be exchangeable in open and dynamic environments, where interacting users do not necessarily share a common understanding of the world at hand. This is particularly true in P2P scenarios, where millions of autonomous users (peers) need to cooperate by sharing their resources (such as data and services). We(More)
Context-aware systems are pervading everyday life, therefore context modeling is becoming a relevant issue and an expanding research field. This survey has the goal to provide a comprehensive evaluation framework, allowing application designers to compare context models with respect to a given target application; in particular we stress the analysis of(More)
More and more often, we face the necessity of extracting appropriately reshaped knowledge from an integrated representation of the information space. Be such a global representation a central database, a global view of several ones or an ontological representation of an information domain, we face the need to define personalised views for the knowledge(More)
A declarative SQL-like language and a middleware infrastructure are presented for collecting data from different nodes of a pervasive system. Data management is performed by hiding the complexity due to the large underlying heterogeneity of devices, which can span from passive RFID(s) to ad hoc sensor boards to portable computers. An important feature of(More)
The design of very small databases for smart cards and for portable embedded systems is deeply constrained by the peculiar features of the physical medium. We propose a joint approach to the logical and physical database design phases and evaluate several data structures with respect to the performance, power consumption, and endurance parameters of(More)