Investigating Opinion Mining through Language Varieties: a Case Study of Brazilian and European Portuguese tweets Douglas Vitório author Ellen Polliana Ramos Souza author Ingryd Pereira author Adriano Oliveira author 2017-10 text Proceedings of the 11th Brazilian Symposium in Information and Human Language Technology Gustavo Henrique Paetzold editor Vládia Pinheiro editor Sociedade Brasileira de Computação Uberlândia, Brazil conference publication vitorio-etal-2017-investigating https://aclanthology.org/W17-6607/ 2017-10 43 52