New markov chain based methods for single and cross-domain sentiment classification

Nowadays communication is switching from a centralized scenario, where communication media like newspapers, radio, TV programs produce information and people are just consumers, to a completely different decentralized scenario, where everyone is potentially an information producer through the use of social networks, blogs, forums that allow a real-time worldwide information exchange. These new instruments, as a result of their widespread diffusion, have started playing an important socio-economic role. They are the most used communication media and, as a consequence, they constitute the main source of information enterprises, political parties and other organizations can rely on. Analyzing data stored in servers all over the world is feasible by means of Text Mining techniques like Sentiment Analysis, which aims to extract opinions from huge amount of unstructured texts. This could lead to determine, for instance, the user satisfaction degree about products, services, politicians and so on. In this context, this dissertation presents new Document Sentiment Classification methods based on the mathematical theory of Markov Chains. All these approaches bank on a Markov Chain based model, which is language independent and whose killing features are simplicity and generality, which make it interesting with respect to previous sophisticated techniques. Every discussed technique has been tested in both Single-Domain and Cross-Domain Sentiment Classification areas, comparing performance with those of other two previous works. The performed analysis shows that some of the examined algorithms produce results comparable with the best methods in literature, with reference to both single-domain and cross-domain tasks, in $2$-classes (i.e. positive and negative) Document Sentiment Classification. However, there is still room for improvement, because this work also shows the way to walk in order to enhance performance, that is, a good novel feature selection process would be enough to outperform the state of the art. Furthermore, since some of the proposed approaches show promising results in $2$-classes Single-Domain Sentiment Classification, another future work will regard validating these results also in tasks with more than $2$ classes.

La competenza comunicativa in giapponese: indagine empirica sulle difficoltà frequenti degli apprendenti italofoni in interazioni orali

Smooth intercultural communication requires very complex tasks, especially when participants are very different in their cultural and linguistic backgrounds: this is the case of native Italian and Japanese speakers. A further difficulty in such a context can be found in the usage of a foreign language not mastered perfectly by speakers, which is the case for Italian intermediate learners of Japanese. The aim of this study is therefore to identify the linguistic difficulties common among Italian learners of Japanese as a foreign language and to further examine the consequences of incorrect pragma-linguistic deliveries in actual conversations. To this end, a series of linguistic aspects selected on the basis of the author's experience have been taken into consideration. Some aspects are expected to be difficult to master because of linguistic differences between Italian and Japanese, while some may be difficult due to their connection to the specific Japanese cultural context. The present study consists of six parts. The Introduction presents the state of the art on the research topic and defines the purpose of this research. Chapter 1 outlines the linguistic aspects of the Japanese language investigated in the study, specifically focusing on the following topics: writing system, phonology, loan words, numbers, ellipsis, levels of speech and honorifics. Chapter 2 presents an overview of the environment of teaching Japanese as a foreign language in the university setting in Italy. In Chapter 3 the first phase of the research is described, i.e. an online survey aimed at identifying the most problematic linguistic aspects. Chapter 4 presents the second phase of this study: a series of oral interactions between Japanese and Italian native speakers, conversing exclusively in Japanese, focusing on the management of misunderstandings with the use of actual linguistic data. The Conclusion outlines the results and possible future developments.