Ana Simonet

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The Horizontal Fragmentation (HF) is a process for reducing the number of disk access to execute a query by reducing the number of irrelevant objects accessed. In this paper, we present horizontal fragmentation based on a set of queries, and develop strategies for two versions of HF: primary and derived. Primary horizontal fragmentation of a class is(More)
Horizontal partitioning is a logical database design technique which facilitates efficient execution of queries by reducing the irrelevant objects accessed. Given a set of most frequently executed queries on a class, the horizontal partitioning generates horizontal class fragments (each of which is a subset of object instances of the class), that meet the(More)
This paper deals with the problem of missing values in decision trees during classification. Our approach is derived from the ordered attribute trees method, proposed by Lobo and Numao in 2000, which builds a decision tree for each attribute and uses these trees to fill the missing attribute values. Our method takes into account the dependence between(More)
Description logics have powerful deductive capabilities but rely on a weakly structured model. Databases provide storage optimization and offer better structuring capacities, especially within the object-oriented paradigm. We propose a model which offers the deductive capabilities of description logics and the structuring possibilities of the object(More)
Nowadays data management systems and knowledge management systems tend to converge. Our work is part of the OSIRIS data and knowledge management system. This system is centered on views which are said object-preserving (i.e. they do not create new objects). Our work led to the construction of a model for the OSIRIS System inspired from those of Description(More)
Instance (or object) classification in a knowledge base management system is the very same problem as view determination in an object DBMS, where views are subsets of classes intensionally defined by constraints. Maintaining the relationship between an object and its current views when the object evolves is a difficult and costly problem. We propose a(More)