VaLexPB: um léxico de valências e diáteses verbais para o português brasileiro baseado no formalismo LFG-XLE

Abstract

This dissertation presents a research work whose main objective was the construction of a computational lexicon of verbal valences and diatheses of Brazilian Portuguese (BP), named VaLexPB, via the LFG-XLE formalism. The work was initially motivated by theoretical, descriptive and applied scarcity and gaps, identified in the linguistic literature and in technical and technological knowledge for the computational processing of Brazilian Portuguese. Particularly, the research aimed at contributing to the development of a lexical-functional computational grammar for BP. To this end, a set of valences in the form of verbal diathesis, based on the Dicionário de Valências Verbais do Português Brasileiro (Perini, 2015), was elaborated and implemented in the LFG-XLE formalism. The theoretical model adopted for the description and analysis was the Lexical-Functional Grammar along with theoretical proposals by Perini (2015, 2019), Cançado (2005) and Cançado and Amaral (2016). The methodological approach used was the one already consolidated in works of computational LFG-XLE grammars construction. One of the goals was also to evaluate the resource regarding its ability to cover BP sentences with the investigated verbs, besides the analysis of the computational and theoretical consequences of the implemented resource. As a result, a set of 389 verbal diatheses was developed, covering sentential constructions licensed by at least 409 verbs of BP. These diatheses allow the analysis of sentences at three levels: two levels of syntactic representation (c-structure and f-structure) and one level of semantic representation (a-structure). Regarding the coverage capacity of VaLexPB, tests showed that it managed to cover over 90% of new sentences licensed by the implemented verbs. The results also showed that this resource has a significant degree of ambiguity, producing an average of 2.8 to 3.7 solutions per sentence (considering development and coverage tests), something that still needs to be worked on in future work in order to include restrictions that might reduce this ambiguity. Despite the improvements needed, the developed resource presents great relevance and usefulness, as it contributes, in the theoretical side, to the current knowledge about the nature and functioning of the BP verbal lexicon; and fro the practical side, it extends a BP computational LFG grammar, enriching the computational processing scenario of this language.