Elliphant: Improved Automatic Detection of Zero Subjects and Impersonal Constructions in Spanish Luz Rello author Ricardo Baeza-Yates author Ruslan Mitkov author 2012-04 text Proceedings of the 13th Conference of the European Chapter of the Association for Computational Linguistics Walter Daelemans editor Association for Computational Linguistics Avignon, France conference publication rello-etal-2012-elliphant https://aclanthology.org/E12-1072/ 2012-04 706 715