Verb Sense Disambiguation
Doutor Nuno Jo, Neves Mamede · 2013
This thesis addresses the problem of Verb Sense Disambiguation (VSD) in European Portuguese. Verb Sense Disambiguation is a sub-problem of the Word Sense Disambiguation (WSD) problem, that tries to identify in which sense a polissemic word is used in a given sentence. Thus a sense inventory for each word (or lemma) must be used. For the VSD problem, this sense inventory consisted in a lexiconsyntactic classification of the most frequent verbs in European Portuguese (ViPEr). Two approaches to VSD were considered. The first, rule-based, approach makes use of the lexical, syntactic and semantic descriptions of the verb senses present in ViPEr to determine the meaning of a verb. The second approach uses machine learning with a set of features commonly used in the WSD problem to determine the correct meaning of the target verb. Both approaches were tested in several scenarios to determine the impact of different features and different combinations of methods. The baseline accuracy of 84%, resulting from the most frequent sense for each verb lemma, was both surprisingly high and hard to surpass. Still, both approaches provided some improvement over this value. The best combination of the two techniques and the baseline yielded an accuracy of 87.2%, a gain of 3.2% above the baseline. Palavras Chave Keywords