Resolving prepositional phrase attachment ambiguities in Spanish with a classifier ∗ Resolviendo las ambigüedades de adjunción de sintagmas preposicionales en castellano con un clasificador

In this paper we present a classifier that solves a certain kind of ambiguities in syntactic structure for Spanish, namely, ambiguities as to the point of adjunction of a prepositional phrase in the syntactic structure of a sentence (PP attachment). As a starting point, we used EsTxala dependency grammar for Spanish, integrated within FreeLing, with an accuracy score of 61 % on PP adjunction. Our target is to develop a specialized module for for PP attachment, so that the syntactic analyzer combines dependency grammar’s manual rules with statistical information infered out of a classifier. We have evaluated different classifiers and different features to characterize PPattachment ambiguities. Our best approaches improve the performance of EsTxala by 20 points, but are still far from the performance of unsupervised methods reporting 94 % accuracy. We gained insight on the factors governing the disambiguation of PP attachment ambiguities, which will arguably let us build lighter models that can be easily integrated within a general-purpose analyzer as FreeLing.