Vertical partitioning, in which attributes of a relation are
assigned to partitions, is aimed at improving database
performance. We extend previous research that is based on
a single relation to multi-relation database environment,
by including referential integrity constraints, access time

Data base management evolved during the sixties and seventies. The evolution period was protracted. Many driving forces impacted the evolution and it is the aim of this paper to analyze these driving forces (some technical and some political) and to…

This paper shows models of data description that incorporate uncertainty like models of data extension EER, IFO among others. These database modeling tools are compared with the pattern FuzzyEER proposed by us, which is an extension of the EER model…

The Web has became an obiquitous resource for distributed computing making it relevant to investigate new ways of providing efficient access to services available at dedicated sites. Efficiency is an ever-increasing demand which can be only satisfied with the development…

This paper is an attempt to define how a
specific data structure might be used to
store, in a persistent manner, temporal
information during a computer simulation.
In particular, it considers the sort of
temporal information generated during a
discrete…

In cases of extremely imbalanced dataset with high dimensions, standard machine learning techniques tend to be overwhelmed by the large classes. This paper rebalances skewed datasets by compressing the majority class. This approach combines Vector Quantization and Support Vector Machine…

In a scene where stakeholders are geographically distributed, communication presents new challenges for research areas. Considering the characteristics of interpersonal communication and the virtual area where it is carried out, the importance of applying interdisciplinary approaches, such as Cognitive Engineering,…

Similarity search is a fundamental operation for applications that deal with unstructured data sources. In this paper we propose a new pivot-based method for similarity search, called Sparse Spatial Selection (SSS).
The main characteristic of this method is that it…

The metric spaces model formalizes the similarity search concept in nontraditional databases. The goal is to build an index designed to save distance computations when answering similarity queries later. A large class of algorithms to build the index are based…

Ontology mapping involves the task of finding similarities among overlapping sources by using ontologies. In a Federated System in which distributed, autonomous and heterogeneous information sources must be integrated, ontologies have emerged as tools to solve semantic heterogeneity problems. In…