Examinando por Autor "Lyhyaoui, Abdelouahid"

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Creating Modular-like Ensembles by Output Clustering
(2009-07-30T09:15:03Z) Mora Jiménez, Inma; Lyhyaoui, Abdelouahid; Arenas García, J.; Figueiras Vidal, Aníbal R
In this paper we consider the possibility of replacing the output layer of Multi- Layer Perceptrons (MLPs) by local schemes when dealing with classification problems. In order to open the possibility of developing LMS-trainable models, and posterior adaptive schemes, we apply a trainable version of the classical k-Nearest Neighbour classifier (kNN) named kNN-Learning Vector Classifier. We develop the corresponding training formulas for the whole resulting structure and apply it to some classification benchmark problems. The experimental results give evidence of the nearly systematic advantage of our proposal with respect to MLPs, as well as of their competitive performance regarding the Modular Neural Networks (MNNs), which have a similar philosophy as our approach.
Sample Selection Via Clustering to Construct Support Vector-Like Classifiers
(2009-07-29T15:18:19Z) Lyhyaoui, Abdelouahid; Martínez Ramón, M; Mora Jiménez, Inma; Vázquez Castro, M.A; Sancho Gómez, JL; Figueiras Vidal, Aníbal R
This paper explores the possibility of constructing RBF classifiers which, somewhat like support vector machines, use a reduced number of samples as centroids, by means of selecting samples in a direct way. Because sample selection is viewed as a hard computational problem, this selection is done after a previous vector quantization: this way obtaining also other similar machines using centroids selected from those that are learned in a supervised manner. Several forms of designing these machines are considered, in particular with respect to sample selection; as well as some different criteria to train them. Simulation results for well-known classification problems show very good performance of the corresponding designs, improving that of support vector machines and reducing substantially their number of units. This shows that our interest in selecting samples (or centroids) in an efficient manner is justified. Many new research avenues appear from these experiments and discussions, as suggested in our conclusions.