Atalaya at TASS 2019: Data Augmentation and Robust Embeddings for Sentiment Analysis

In this article we describe our participation in TASS 2019, a shared task aimed at the detection of sentiment polarity of Spanish tweets. We combined different representations such as bag-of-words, bag-of-characters, and tweet embeddings. In particular, we trained robust subword-aware word embeddings and computed tweet representations using a weighted-averaging strategy. We also used two data augmentation techniques to deal with data scarcity: two-way translation augmentation, and instance crossover augmentation, a novel technique that generates new instances by combining halves of tweets. In experiments, we trained linear classifiers and ensemble models, obtaining highly competitive results despite the simplicity of our approaches.

El Lenguaje Natural como Lenguaje Formal

Formal languages theory is useful for the study of natural language. In particular, it is of interest to study the adequacy of the grammatical formalisms to express syntactic phenomena present in natural language. First, it helps to draw hypothesis about the nature and complexity of the speaker-hearer linguistic competence, a fundamental question in linguistics and other cognitive sciences. Moreover, from an engineering point of view, it allows the knowledge of practical limitations of applications based on those formalisms. In this article I introduce the adequacy problem of grammatical formalisms for natural language, also introducing some formal language theory concepts required for this discussion. Then, I review the formalisms that have been proposed in history, and the arguments that have been given to support or reject their adequacy. ----- La teor\'ia de lenguajes formales es \'util para el estudio de los lenguajes naturales. En particular, resulta de inter\'es estudiar la adecuaci\'on de los formalismos gramaticales para expresar los fen\'omenos sint\'acticos presentes en el lenguaje natural. Primero, ayuda a trazar hip\'otesis acerca de la naturaleza y complejidad de las competencias ling\"u\'isticas de los hablantes-oyentes del lenguaje, un interrogante fundamental de la ling\"u\'istica y otras ciencias cognitivas. Adem\'as, desde el punto de vista de la ingenier\'ia, permite conocer limitaciones pr\'acticas de las aplicaciones basadas en dichos formalismos. En este art\'iculo hago una introducci\'on al problema de la adecuaci\'on de los formalismos gramaticales para el lenguaje natural, introduciendo tambi\'en algunos conceptos de la teor\'ia de lenguajes formales necesarios para esta discusi\'on. Luego, hago un repaso de los formalismos que han sido propuestos a lo largo de la historia, y de los argumentos que se han dado para sostener o refutar su adecuaci\'on.