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Traditional query processing provides exact answers to queries. However, in many applications, the response time of exact answers is often longer than what is acceptable. Approximate query processing has emerged as an alternative approach to give to the user an answer in a short time. The goal is to provide an estimated result in one order of magnitude less(More)
Neural networks is one of the techniques used for time series analysis. The performance of neural networks is affected by some parameters such as neural network structure and the quality of data preprocessing. These parameters need to be explored in order to obtain an optimal neural network. However, the manual establishment of different neural networks(More)
Predicting the academic progress of student is an issue faced by many public universities in emerging countries. Although, those institutions stores large amounts of educational data, they fail to recognize the students that are in danger to leave the system. This paper presents a novel architecture that uses EDM techniques to predict and to identify those(More)
ParGRES is a middleware aimed to efficiently process heavy weight queries, typical of OLAP, on top of a database cluster. ParGRES achieves query processing speed-up through intraand inter-query parallelism in a PC cluster environment with database replication and virtual partitioning. It accelerates both individual queries and system throughput. Our(More)
Many works have been proposed in order to improve the recommendation accuracy. Algorithms aiming to improve recommendation accuracy have been developed and evaluated. These algorithms usually work with training data sets which are learned and used to make predictions on users' tastes. The training data set choice is a difficult task not only due to the(More)
It’s a well-known fact that new GIS applications need to keep track of temporal information. However, the most widely used spatial index, the R-Tree and its variants, do not preserve the evolution of bounding boxes. Some new indexing structures were proposed in the literature that allows the retrieving of present and past states of data. In this paper we(More)