Attitydanalys är ett delfält av språkteknologi (NLP) som försöker analysera känslan av skriven text. Detta är ett komplext problem som medför många utmaningar. Av denna anledning har det studerats i stor utsträckning. Under de senaste åren har traditionella maskininlärningsalgoritmer eller handgjord metodik använts och givit utmärkta resultat. Men den senaste renässansen för djupinlärning har växlat om intresse till end to end deep learning-modeller.Å ena sidan resulterar detta i mer kraftfulla modeller men å andra sidansaknas klart matematiskt resonemang eller intuition för dessa modeller. På grund av detta görs ett försök i denna avhandling med att kasta ljus på nyligen föreslagna deep learning-arkitekturer för attitydklassificering. En studie av deras olika skillnader utförs och ger empiriska resultat för hur ändringar i strukturen eller kapacitet hos modellen kan påverka exaktheten och sättet den representerar och ''förstår'' meningarna. / Sentiment analysis is a subfield of natural language processing (NLP) that attempts to analyze the sentiment of written text.It is is a complex problem that entails different challenges. For this reason, it has been studied extensively. In the past years traditional machine learning algorithms or handcrafted methodologies used to provide state of the art results. However, the recent deep learning renaissance shifted interest towards end to end deep learning models. On the one hand this resulted into more powerful models but on the other hand clear mathematical reasoning or intuition behind distinct models is still lacking. As a result, in this thesis, an attempt to shed some light on recently proposed deep learning architectures for sentiment classification is made.A study of their differences is performed as well as provide empirical results on how changes in the structure or capacity of a model can affect its accuracy and the way it represents and ''comprehends'' sentences.

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In this thesis we have present effective approaches for two classic Nature Language Processing tasks: Multi-label Text Classification(MLTC) and Sentiment Analysis(SA) based on two datasets. For MLTC, a robust deep learning approach based on convolution neural network(CNN) has been introduced. We have done this on almost one million records with a related label list consists of 20 labels. We have divided our data set into three parts, training set, validation set and test set. Our CNN based model achieved great result measured in F1 score. For SA, data set was more informative and well-structured compared with MLTC. A traditional word embedding method, Word2Vec was used for generating word vector of each text records. Following that, we employed several classic deep learning models such as Bi-LSTM, RCNN, Attention mechanism and CNN to extract sentiment features. In the next step, a classification frame was designed to graded. At last, the start-of-art language model, BERT which use transfer learning method was employed. In conclusion, we compared performance of RNN-based model, CNN-based model and pre-trained language model on classification task and discuss their applicability. / Thesis / Master of Science in Electrical and Computer Engineering (MSECE) / This theis purposed two deep learning solution to both multi-label classification problem and sentiment analysis problem.

This dissertation focuses on the review understanding problem, which has gained attention from both industry and academia, and has found applications in many downstream tasks, such as recommendation, information retrieval and review summarization. In this dissertation, we aim to develop machine learning and natural language processing tools to understand and learn structured knowledge from unstructured reviews, which can be investigated in three research directions, including understanding review corpora, understanding review documents, and understanding review segments. For the corpus-level review understanding, we have focused on discovering knowledge from corpora that consist of short texts. Since they have limited contextual information, automatically learning topics from them remains a challenging problem. We propose a semantics-assisted non-negative matrix factorization model to deal with this problem. It effectively incorporates the word-context semantic correlations into the model, where the semantic relationships between the words and their contexts are learned from the skip-gram view of a corpus. We conduct extensive sets of experiments on several short text corpora to demonstrate the proposed model can discover meaningful and coherent topics. For document-level review understanding, we have focused on building interpretable and reliable models for the document-level multi-aspect sentiment analysis (DMSA) task, which can help us to not only recover missing aspect-level ratings and analyze sentiment of customers, but also detect aspect and opinion terms from reviews. We conduct three studies in this research direction. In the first study, we collect a new DMSA dataset in the healthcare domain and systematically investigate reviews in this dataset, including a comprehensive statistical analysis and topic modeling to discover aspects. We also propose a multi-task learning framework with self-attention networks to predict sentiment and ratings for given aspects. In the second study, we propose corpus-level and concept-based explanation methods to interpret attention-based deep learning models for text classification, including sentiment classification. The proposed corpus-level explanation approach aims to capture causal relationships between keywords and model predictions via learning importance of keywords for predicted labels across a training corpus based on attention weights. We also propose a concept-based explanation method that can automatically learn higher level concepts and their importance to model predictions. We apply these methods to the classification task and show that they are powerful in extracting semantically meaningful keywords and concepts, and explaining model predictions. In the third study, we propose an interpretable and uncertainty aware multi-task learning framework for DMSA, which can achieve competitive performance while also being able to interpret the predictions made. Based on the corpus-level explanation method, we propose an attention-driven keywords ranking method, which can automatically discover aspect terms and aspect-level opinion terms from a review corpus using the attention weights. In addition, we propose a lecture-audience strategy to estimate model uncertainty in the context of multi-task learning. For the segment-level review understanding, we have focused on the unsupervised aspect detection task, which aims to automatically extract interpretable aspects and identify aspect-specific segments from online reviews. The existing deep learning-based topic models suffer from several problems such as extracting noisy aspects and poorly mapping aspects discovered by models to the aspects of interest. To deal with these problems, we propose a self-supervised contrastive learning framework in order to learn better representations for aspects and review segments. We also introduce a high-resolution selective mapping method to efficiently assign aspects discovered by the model to the aspects of interest. In addition, we propose using a knowledge distillation technique to further improve the aspect detection performance. / Doctor of Philosophy / Nowadays, online reviews are playing an important role in our daily lives. They are also critical to the success of many e-commerce and local businesses because they can help people build trust in brands and businesses, provide insights into products and services, and improve consumers' confidence. As a large number of reviews accumulate every day, a central research problem is to build an artificial intelligence system that can understand and interact with these reviews, and further use them to offer customers better support and services. In order to tackle challenges in these applications, we first have to get an in-depth understanding of online reviews. In this dissertation, we focus on the review understanding problem and develop machine learning and natural language processing tools to understand reviews and learn structured knowledge from unstructured reviews. We have addressed the review understanding problem in three directions, including understanding a collection of reviews, understanding a single review, and understanding a piece of a review segment. In the first direction, we proposed a short-text topic modeling method to extract topics from review corpora that consist of primary complaints of consumers. In the second direction, we focused on building sentiment analysis models to predict the opinions of consumers from their reviews. Our deep learning models can provide good prediction accuracy as well as a human-understandable explanation for the prediction. In the third direction, we develop an aspect detection method to automatically extract sentences that mention certain features consumers are interested in, from reviews, which can help customers efficiently navigate through reviews and help businesses identify the advantages and disadvantages of their products.

An important means for disseminating information on social media platforms is by including URLs that point to external sources in user posts. In X, formally known as Twitter, we estimate that about 21% of the daily stream of English-language posts contain URLs. Given this prevalence, we assert that studying URLs in social media holds significant importance as they play a pivotal part in shaping the flow of information and influencing user behavior. Examining hyperlinked posts can help us gain valuable insights into online discourse and detect emerging trends. The first aspect of our analysis is the study of users' intentions behind including URLs in social media posts. We argue that gaining insights about the users' motivations for posting with URLs has multiple applications, including the appropriate treatment and processing of these posts in other tasks. Hence, we build a comprehensive taxonomy containing the various intentions behind sharing URLs on social media. In addition, we explore the labeling of intentions via the use of crowdsourcing. In addition to the intentions aspect of hyperlinked posts, we analyze their structure relative to the content of the web documents pointed to by the URLs. Hence, we define, and analyze the segmentation problem of hyperlinked posts and develop an effective algorithm to solve it. We show that our solution can benefit sentiment analysis on social media. In the final aspect of our analysis, we investigate the emergence of news outlets posing as local sources, known as "pink slime", and their spread on social media. We conduct a comprehensive study investigating hyperlinked posts featuring pink slime websites. Through our analysis of the patterns and origins of posts, we discover and extract syntactical features and utilize them for developing a classification approach to detect such posts. Our approach has achieved an accuracy rate of 92.5%. / Computer and Information Science

Yes / The governments, nowadays, throughout the world are increasingly becoming dependent on public opinion regarding the framing and implementation of certain policies for the welfare of the general public. The role of social media is vital to this emerging trend. Traditionally, lack of public participation in various policy making decision used to be a major cause of concern particularly when formulating and evaluating such policies. However, the exponential rise in usage of social media platforms by general public has given the government a wider insight to overcome this long pending dilemma. Cloud-based e-governance is currently being realized due to IT infrastructure availability along with mindset changes of government advisors towards realizing the various policies in a best possible manner. This paper presents a pragmatic approach that combines the capabilities of both cloud computing and social media analytics towards efficient monitoring and controlling of governmental policies through public involvement. The proposed system has provided us some encouraging results, when tested for Goods and Services Tax (GST) implementation by Indian government and established that it can be successfully implemented for efficient policy making and implementation.

Yes / The online shopping is increasing rapidly because of its convenience to buy from home and comparing products from their reviews written by other purchasers. When people buy a product, they express their emotions about that product in the form of review. In Indian context, it is found that the reviews contain Hindi text along with English. It is also found that most of the Hindi text contains opinionated words like bahut achha, bakbas, pesa wasool etc. We have tried to find out different Hindi texts appearing in product reviews written on Indian E-commerce portals. We have also developed a system which takes all those reviews containing Hindi as well as English texts and find out the sentiment expressed in that review for each attribute of the product as well as a final review of the product.

Background: Twitter, Facebook, WordPress, etc. act as the major sources of information exchange in today's world. The tweets on Twitter are mainly based on the public opinion on a product, event or topic and thus contains large volumes of unprocessed data. Synthesis and Analysis of this data is very important and difficult due to the size of the dataset. Sentiment analysis is chosen as the apt method to analyse this data as this method does not go through all the tweets but rather relates to the sentiments of these tweets in terms of positive, negative and neutral opinions. Sentiment Analysis is normally performed in 3 ways namely Machine learning-based approach, Sentiment lexicon-based approach, and Hybrid approach. The Machine learning based approach uses machine learning algorithms and deep learning algorithms for analysing the data, whereas the sentiment lexicon-based approach uses lexicons in analysing the data and they contain vocabulary of positive and negative words. The Hybrid approach uses a combination of both Machine learning and sentiment lexicon approach for classification. Objectives: The primary objectives of this research are: To identify the algorithms and metrics for evaluating the performance of Machine Learning Classifiers. To compare the metrics from the identified algorithms depending on the size of the dataset that affects the performance of the best-suited algorithm for sentiment analysis. Method: The method chosen to address the research questions is Experiment. Through which the identified algorithms are evaluated with the selected metrics. Results: The identified machine learning algorithms are Naïve Bayes, Random Forest, XGBoost and the deep learning algorithm is CNN-LSTM. The algorithms are evaluated with respect to the metrics namely precision, accuracy, F1 score, recall and compared. CNN-LSTM model is best suited for sentiment analysis on twitter data with respect to the selected size of the dataset. Conclusion: Through the analysis of results, the aim of this research is achieved in identifying the best-suited algorithm for sentiment analysis on twitter data with respect to the selected dataset. CNN-LSTM model results in having the highest accuracy of 88% among the selected algorithms for the sentiment analysis of Twitter data with respect to the selected dataset.

Com o avanço da Internet pelo mundo, as pessoas passaram a interagir cada vez mais com a Web, principalmente após o surgimento das redes sociais, criando conteúdo que pode ser explorado de diversas formas. Esse aumento de usuários tem sido global, ou seja, pessoas de diversos países passaram a produzir textos de diversos idiomas. Esses textos compõem um rico conteúdo para Análise de Sentimentos Multilíngue. A maior parte dos trabalhos da área se foca em Mineração de Opinião, analisando o sentimento através da polaridade. Outro tipo de sentimento que tem atraído atenção é a emoção, embora não seja amplamente explorada a Análise de Sentimentos Multilíngue usando emoção. Este trabalho utiliza técnicas geralmente usadas para Mineração de Opinião e polaridade para Análise de Sentimentos Multilíngues usando emoção. O objetivo deste trabalho é comparar diferentes combinações de aprendizado de máquina supervisionado e tradução automática para criar corpora em diferentes idiomas a partir de corpora anotados já existentes. As duas formas de utilizar as traduções comparadas são: criando classificadores de emoção separados por idiomas, chamados monolíngues, e criando um classificador composto do idioma original e das traduções, chamado multilíngue. É feito ainda um experimento cruzando dois corpora, visando avaliar o uso da tradução de um corpus com os textos originais do outro. Os resultados dos experimentos mostram não apenas o sucesso de analisar emoção usando aprendizado supervisionado e tradução automática, mas que o classificador multilíngue supera os classificadores monolíngues. O experimento cruzando os corpora mostra que para algumas emoções os corpora estão alinhados, mas que para outras é preciso que haja maior similaridade nos textos. / With the growth of the Internet around the world, people began to interact more and more with the Web, especially after the emergence of social networks, creating content that can be exploited in several ways. This increase in the number of users has been global, that is, people from different countries started producing texts in several languages. These texts comprise a rich content for Multilingual Sentiment Analysis. Most of the work in the area focus in Opinion Mining, analyzing the feeling through polarity. Another type of feeling that has attracted attention is emotion, although not extensively explored in Multilingual Sentiment Analysis. This work uses techniques commonly used for Opinion Mining and polarity for Multilingual Sentiment Analysis using emotion. The objective of this study is to compare different combinations of supervised machine learning and automatic translation to create corpora in different languages from existing annotated corpora. The two ways to use the translations compared are: creating emotion classifiers separated by languages, called monolingual, and creating a composed classifier, with the original language and it’s translations, called multilingual. An experiment crossing the two corpora used is made, to evaluate the use of the translation of one corpus with the original texts of the other. The results of the experiments show not only the success of analysing emotion using supervised machine learning and automatic translation, but that the multilingual classifier exceeds the monolingual classifiers. The experiment crossing the corpora shows that to some emotions the corpora are aligned, but for others there needs to be greater similarity in the texts.

Com o avanço da Internet pelo mundo, as pessoas passaram a interagir cada vez mais com a Web, principalmente após o surgimento das redes sociais, criando conteúdo que pode ser explorado de diversas formas. Esse aumento de usuários tem sido global, ou seja, pessoas de diversos países passaram a produzir textos de diversos idiomas. Esses textos compõem um rico conteúdo para Análise de Sentimentos Multilíngue. A maior parte dos trabalhos da área se foca em Mineração de Opinião, analisando o sentimento através da polaridade. Outro tipo de sentimento que tem atraído atenção é a emoção, embora não seja amplamente explorada a Análise de Sentimentos Multilíngue usando emoção. Este trabalho utiliza técnicas geralmente usadas para Mineração de Opinião e polaridade para Análise de Sentimentos Multilíngues usando emoção. O objetivo deste trabalho é comparar diferentes combinações de aprendizado de máquina supervisionado e tradução automática para criar corpora em diferentes idiomas a partir de corpora anotados já existentes. As duas formas de utilizar as traduções comparadas são: criando classificadores de emoção separados por idiomas, chamados monolíngues, e criando um classificador composto do idioma original e das traduções, chamado multilíngue. É feito ainda um experimento cruzando dois corpora, visando avaliar o uso da tradução de um corpus com os textos originais do outro. Os resultados dos experimentos mostram não apenas o sucesso de analisar emoção usando aprendizado supervisionado e tradução automática, mas que o classificador multilíngue supera os classificadores monolíngues. O experimento cruzando os corpora mostra que para algumas emoções os corpora estão alinhados, mas que para outras é preciso que haja maior similaridade nos textos. / With the growth of the Internet around the world, people began to interact more and more with the Web, especially after the emergence of social networks, creating content that can be exploited in several ways. This increase in the number of users has been global, that is, people from different countries started producing texts in several languages. These texts comprise a rich content for Multilingual Sentiment Analysis. Most of the work in the area focus in Opinion Mining, analyzing the feeling through polarity. Another type of feeling that has attracted attention is emotion, although not extensively explored in Multilingual Sentiment Analysis. This work uses techniques commonly used for Opinion Mining and polarity for Multilingual Sentiment Analysis using emotion. The objective of this study is to compare different combinations of supervised machine learning and automatic translation to create corpora in different languages from existing annotated corpora. The two ways to use the translations compared are: creating emotion classifiers separated by languages, called monolingual, and creating a composed classifier, with the original language and it’s translations, called multilingual. An experiment crossing the two corpora used is made, to evaluate the use of the translation of one corpus with the original texts of the other. The results of the experiments show not only the success of analysing emotion using supervised machine learning and automatic translation, but that the multilingual classifier exceeds the monolingual classifiers. The experiment crossing the corpora shows that to some emotions the corpora are aligned, but for others there needs to be greater similarity in the texts.