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To support applications, such as efficient browsing in large knowledge bases and cooperative knowledge discovery in large databases, the concept of rule similarity is essential. In this paper we define such a measure, called distance, and then put in the service of various knowledge exploration processes. Rule distances allow us to place all the available knowledge on a “map”, in which proximity reflects...
In this paper, we describe a system capable of extracting textual information from images of structured documents. In particular the model and the algorithms we described are used to process forms in which the information fields can not be located only by their position on the page, but can also be identified after locating the corresponding instruction fields. The proposed model is based on attributed...
The paper describes techniques for the automatic construction of hypertexts starting from various legal source documents: statutes, law reports, and so on. The approach described is based on the use of text grammars and parsers. It is general and formal enough that converters for new classes of documents can be written quite easily. We describe the processes of text reconnaissance and grammar construction...
Effective design and management tool integration within a design support environment is a problem common to all design applications, but can be acute in some artistic applications. Reasons are explained through analysis of tools integration problems encountered in music composition. The problems identified stem from the experimental and volatile nature of the tools, a predominance of “foreign” and...
The first step for developing an heterogeneous federated database consists in translating local schemas into a canonical data model. This paper offers a method to transform a relational schema into an equivalent object-oriented one. We study in particular the translation of the n-ary relationship tables (n>2). The canonical data model we are using is the IFO2 data model [16], [17], [24]. We translate...
Extended set operators defined originally for nested relations form a basis for the set operators for complex objects because the common approach based on the application of set operators to sets of oids (based on the equality of oids) alone is not sufficient as pointed out in the literature. Extended set operators operate directly on nested relations and produce nested relations. Hence, restructuring...
Several techniques for dereferencing persistent pointers have been proposed to improve performance of object-oriented database systems. This paper describes performance experiments to compare several techniques of dereferencing persistent pointers including swizzling and nonswizzling approaches in a memory-mapped I/O environment, and discusses trade-offs among them. All techniques were implemented...
We describe a tool for physical database design based on a combination of theoretical and pragmatic approaches. The tool takes as input a relational schema, the workload defined on the schema, and some additional database characteristics and produces as output a physical schema. For the time being, the tool is tuned towards Ingres.
In multi-level secure database management system (MLS/DBMS), every transaction and data has associated with a unique security. Concurrent transactions on MLS/DBMS potentially have conflicts while accessing the shared data. The conflicts result in some of the conflicting transactions to be delayed. If the delayed transactions have been cleared at low security level, an information may flow downward...
The object-oriented database management systems store references to objects (implicit joins, precomputed joins), and use path expressions in query languages. One way of executing path expressions is pointer chasing of precomputed joins. However it has been previously shown that converting implicit joins to explicit joins during the optimization phase may yield better execution plans. A path expression...
We are presenting the four pivotal problem dimensions of design: organisation, object world, tasks, and communication. We argue that neglecting or ignoring one or more of them cannot lead to an optimal design. We offer specific ways to bridge the gaps between these dimensions.
The reason for the work presented in this paper is the lack of an extension of a relational database system, which is able to transform one basic bill of material into the several types of bills of material of the same product needed in an enterprise. We introduce a rule-driven transformation processor for bill of material data, which allows each organisation unit of an enterprise to use the same...
In this paper we present Cicero, a system for the assisted planning of personalized itineraries to visit the Ducal Palace in Urbino, Italy. The graphic interface gives users a structured and exhaustive view of the artistic content of the museum, and enables them to choose consciously which aspects to privilege during the visit. According to the user preferences, the system derives a set of constraints...
The framework of our research originates from natural language processing and deductive database technology. Deductive databases possess superior functionality relevant to the efficient solution of many problems in practical applications, yet there still exists no broad acquaintance. As main obstacle we identified the absence of any user-friendly interface. Natural language interfaces have been proposed...
The performance of a disk with two heads per surface separated by a fixed number of cylinders is examined. We derive the probability distribution of arm stops, the expected number of stops as well as the expected number of cylinder clusters, i.e. the number of sets of consecutive compound cylinders. In comparison with a single-headed disk, it is shown that the performance gain may reach 50% on the...
Nested transactions (NTs) allow the decomposition of execution units and finer grained control over concurrency and recovery than conventional, flat transactions. Due to their characteristics, they provide adequate control structures for modeling transactions in several different environments. In this paper, we concentrate on the use of NTs in Knowledge Base Management Systems (KBMSs). With respect to those systems, the allowance for knowledge sharing is an important emerging point, which is going to be imperative for the complete success of KBMSs in the market. Nevertheless, to allow for knowledge sharing, special lock modes must be employed to adequately control the concurrency in KBMSs. We present enhanced lock modes tailored to the KBMS environment, which capture the abstraction relationships' semantics. Additionally, we couple these lock modes to an NT model allowing for upward as well as controlled downward inheritance of locks. Finally, on one hand, our NT model allows for an effective exploitation of intratransaction parallelism, on the other hand, our enhanced lock modes make feasible the exploitation of the inherent parallelism in a knowledge representation approach...
Comparing the behaviour of the workloads of different transactions posed a problem for this research because the review of literature could not find a well-accepted comparison technique that could be relied on for such comparisons. This paper proposes the use of the rate of change of DBMS behaviour against a test parameter as a common basis of comparison between different transaction workloads. The...
With this paper we introduce information security aspects and concepts to the field of Computer Supported Cooperative Work (CSCW). Starting from a functional view of CSCW technology and the definition of the relevant security areas we outline a catalogue of security criteria which should be fulfilled by CSCW applications in order to increase the acceptance and reliability of such systems. Classical...
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