A first approach to the automatic detection of zero subjects and impersonal constructions in Portuguese

In this paper we present a first approximation to the automatic detection of zero subjects and impersonal constructions in Brazilian Portuguese. To the best of our knowledge, this is the first attempt of approaching such task using machine learning in Portuguese. We compiled a corpus containing more than 5,600 instances annotated with the classes to be identified: explicit subjects, zero subjects or pronouns and impersonal constructions. We applied machine learning using linguistically motivated features to classify the instances. The results are modest but promising and provide guidance for future work.