Papers by Francisco Ordoñez
An ensemble of classifiers is a set of classifiers whose predictions are combined in some way to ... more An ensemble of classifiers is a set of classifiers whose predictions are combined in some way to classify new instances. Early research has shown that, in general, an ensemble of classifiers is more accurate than any of the single classifiers in the ensemble. Usually the gains obtained by combining different classifiers are more affected by the chosen classifiers than by the used combination. It is common in the research on this topic to select by hand the right combination of classifiers and the method to combine them, but the approach presented in this work uses genetic algorithms for selecting the classifiers and the combination method to use. Our approach, GA-Ensemble, is inspired by a previous work, called GA-Stacking. GA-Stacking is a method that uses genetic algorithms to find domain-specific Stacking configurations. The main goal of this work is to improve the efficiency of GA-Stacking and to compare GA-Ensemble with current ensemble building techniques. Preliminary results have show that the approach finds ensembles of classifiers whose performance is as good as the best techniques, without having to set up manually the classifiers and the ensemble method.
Natural Language & Linguistic Theory, 1998
Spanish allows its post-verbal subjects to appear in the VSO and VOS configurations. It has been ... more Spanish allows its post-verbal subjects to appear in the VSO and VOS configurations. It has been generally assumed that the second order is generated by the adjunction of the subject to the right (Rizzi 1982, Torrego 1984, and Sun_er 1994). This paper explores an alternative to this traditional view in which this order is generated by the scrambling of the objects to the left. Empirical support in favor of this hypothesis comes from certain syntactic asymmetries between VSO and VOS. Some of these asymmetries reflect the fact that the object c-commands the subject in the VOS order but not in the VSO order. In other cases, the asymmetries show that certain types of objects cannot move to the left to produce the VOS order. This is the result predicted by the constrained nature of scrambling. Specifically, there is a parallel between these alternations in Spanish and the same ones described in scrambling languages (e.g., German or Korean) with SOV and OSV alternations. Finally, this hypothesis supports the line of research put forward by Kayne (1994) for word order in UG, according to which right adjunction is not possible.
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Papers by Francisco Ordoñez