Introduction

摘要

Two thousand five hundred years ago, Democritus said: "Nothing exists except atoms and empty space. Everything else is opinion." Today, this saying is omnipresent, as the state of our social interpretation of reality has been denominated by the "post-truth society". Research in automatic Subjectivity and Sentiment Analysis (SSA), as subtasks of Affective Computing and Natural Language Processing (NLP), has flourished in the past years. The growth in interest in these tasks was motivated by the birth and rapid expansion of the Social Web that made it possible for people all over the world to share, comment or consult content on any given topic. In this context, opinions, sentiments and emotions expressed in Social Media texts have been shown to have a high influence on social and economic behaviour worldwide.