To my parents, Márcio Velmovitsky and Fabiana Elkind Velmovitsky, my sister, Vanessa Elkind Velmovitsky, and my grandparents David Elkind Schwartz and Belinha Saubel Elkind, for the advices and encouragements throughout my life, and for always supporting me in my decisions, no matter what. I would like to thank Professor Lucena for his expert advise and for the opportunity of learning with his experience and knowledge throughout the research process and during my Master degree. To Dr. Marx Leles Viana, for the patience and invaluable support during the making of this work, and to Professor Ruy Luiz Milidiú, for introducing me to the subject of chatbots and encouraging me to pursue further studies in the area. I would like to thanks all my colleagues for their wonderful collaboration. This project would have been imposible without the support of CAPES and PUC-Rio. Thank you.