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The problem of translating view updates to database updates is considered. Both databases and views are modeled as data abstractions. A data abstraction consists of a set of states and of a set of primitive update operators representing state transition functions. It is shown how complex update programs can be built from primitive update operators and how(More)
LOGRES is a new project for the development of extended database systems which is based on the integration of the object-oriented data modelling paradigm and of the rule-based approach for the specification of queries and updates. The data model supports generalization hierarchies and object sharing, the rule-based language extends <italic>Datalog</italic>(More)
We describe a data model for structured office information objects, which we generically call &#8220;documents,&#8221; and a practically useful algebraic language for the retrieval and manipulation of such objects. Documents are viewed as hierarchical structures; their layout (presentation) aspect is to be treated separately. The syntax and semantics of the(More)
Building profiles of registered users of a web site, as in case of a portal, is of importance if it goes beyond collecting the obvious information the user is willing to give at the time of registration. The starting point of this work is the assumption that a community of users is registered on a web site and that for each user a profile is built. Such a(More)
We have introduced the concept of non-obvious user profiles (NOPs) to capture the hypothetical interest of Web users. In this paper we present the design principles and rules of our Gugubarra engine, which is a tool to calculate and visualize these non-obvious user profiles
This paper addresses the issue of how to define clusters of web visitors with respect to their behavior and supposed interests. We will use the non-obvious user profiles (NOPs) approach defined in [10], and present a new clustering algorithm which is a combination of hierarchical clustering together with a centroid based method with priority, which allows(More)