Sentiment Classification of Russian Texts Using Automatically Generated Thesaurus

This paper is devoted to an approach for sentiment classification of Russian texts applying an automatic thesaurus of the subject area. This approach consists of a standard machine learning classifier and a procedure embedded into it, that uses the- saurus relationships for better sentiment analysis. The thesaurus is generated fully automatically and does not require expert’s involvement into classification process. Experiments conducted with the approach and four Russian-language text corpora, show effectiveness of thesaurus application to sentiment classification

Sentiment Classification into Three Classes Applying Multinomial Bayes Algorithm, N-grams, and Thesaurus

The paper is devoted to development of the method that classi?es texts in English and Russian by sentiments into positive, negative, and neutral. The proposed method is based on the Multinomial Naive Bayes classi?er with additional n-grams application. The classi?er is trained either on three classes, or on two contrasting classes with a threshold to separate neutral texts. Experiments with texts on various topics showed signi?cant improvement of classification quality for reviews from a particular domain. Besides, the analysis of thesaurus relationships application to sentiment classification into three classes was done, however it did not show significant improvement of the classification results

Sentiment classification of long newspaper articles based on automatically generated thesaurus with various semantic relationships

The paper describes a new approach for sentiment classification of long texts from newspapers using an automatically generated thesaurus. An important part of the proposed approach is specialized thesaurus creation and computation of term's sentiment polarities based on relationships between terms. The approach's efficiency has been proved on a corpus of articles about American immigrants. The experiments showed that the automatically created thesaurus provides better classification quality than manual ones, and generally for this task our approach outperforms existing ones

A survey on thesauri application in automatic natural language processing

This paper is devoted to investigate efficiency of thesauri use in popular natural language processing (NLP) fields: information retrieval and analysis of texts and subject areas. A thesaurus is a natural language resource that models a subject area and can reflect human expert's knowledge in many NLP tasks. The main target of this survey is to determine how much thesauri affect processing quality and where they can provide better performance. We describe studies that use different types of thesauri, discuss contribution of the thesaurus into achieved results, and propose directions for future research in the thesaurus field

Navigating multilingual news collections using automatically extracted information

We are presenting a text analysis tool set that allows analysts in various fields to sieve through large collections of multilingual news items quickly and to find information that is of relevance to them. For a given document collection, the tool set automatically clusters the texts into groups of similar articles, extracts names of places, people and organisations, lists the user-defined specialist terms found, links clusters and entities, and generates hyperlinks. Through its daily news analysis operating on thousands of articles per day, the tool also learns relationships between people and other entities. The fully functional prototype system allows users to explore and navigate multilingual document collections across languages and time.Comment: This paper describes the main functionality of the JRC's fully-automatic news analysis system NewsExplorer, which is freely accessible in currently thirteen languages at http://press.jrc.it/NewsExplorer/ . 8 page

An Urdu semantic tagger - lexicons, corpora, methods and tools

Extracting and analysing meaning-related information from natural language data has attracted the attention of researchers in various fields, such as Natural Language Processing (NLP), corpus linguistics, data sciences, etc. An important aspect of such automatic information extraction and analysis is the semantic annotation of language data using semantic annotation tool (a.k.a semantic tagger). Generally, different semantic annotation tools have been designed to carry out various levels of semantic annotations, for instance, sentiment analysis, word sense disambiguation, content analysis, semantic role labelling, etc. These semantic annotation tools identify or tag partial core semantic information of language data, moreover, they tend to be applicable only for English and other European languages. A semantic annotation tool that can annotate semantic senses of all lexical units (words) is still desirable for the Urdu language based on USAS (the UCREL Semantic Analysis System) semantic taxonomy, in order to provide comprehensive semantic analysis of Urdu language text. This research work report on the development of an Urdu semantic tagging tool and discuss challenging issues which have been faced in this Ph.D. research work. Since standard NLP pipeline tools are not widely available for Urdu, alongside the Urdu semantic tagger a suite of newly developed tools have been created: sentence tokenizer, word tokenizer and part-of-speech tagger. Results for these proposed tools are as follows: word tokenizer reports $F_1$ of 94.01\%, and accuracy of 97.21\%, sentence tokenizer shows F$_1$ of 92.59\%, and accuracy of 93.15\%, whereas, POS tagger shows an accuracy of 95.14\%. The Urdu semantic tagger incorporates semantic resources (lexicon and corpora) as well as semantic field disambiguation methods. In terms of novelty, the NLP pre-processing tools are developed either using rule-based, statistical, or hybrid techniques. Furthermore, all semantic lexicons have been developed using a novel combination of automatic or semi-automatic approaches: mapping, crowdsourcing, statistical machine translation, GIZA++, word embeddings, and named entity. A large multi-target annotated corpus is also constructed using a semi-automatic approach to test accuracy of the Urdu semantic tagger, proposed corpus is also used to train and test supervised multi-target Machine Learning classifiers. The results show that Random k-labEL Disjoint Pruned Sets and Classifier Chain multi-target classifiers outperform all other classifiers on the proposed corpus with a Hamming Loss of 0.06\% and Accuracy of 0.94\%. The best lexical coverage of 88.59\%, 99.63\%, 96.71\% and 89.63\% are obtained on several test corpora. The developed Urdu semantic tagger shows encouraging precision on the proposed test corpus of 79.47\%

Анализ использования различных типов связей между терминами тезауруса, сгенерированного с помощью гибридных методов, в задачах классификации текстов

The main purpose of the article is to analyze how effectively different types of thesaurus relations can be used for solutions of text classification tasks. The basis of the study is an automatically generated thesaurus of a subject area, that contains three types of relations: synonymous, hierarchical and associative. To generate the thesaurus the authors use a hybrid method based on several linguistic and statistical algorithms for extraction of semantic relations. The method allows to create a thesaurus with a sufficiently large number of terms and relations among them. The authors consider two problems: topical text classification and sentiment classification of large newspaper articles. To solve them, the authors developed two approaches that complement standard algorithms with a procedure that take into account thesaurus relations to determine semantic features of texts. The approach to topical classification includes the standard unsupervised BM25 algorithm and the procedure, that take into account synonymous and hierarchical relations of the thesaurus of the subject area. The approach to sentiment classification consists of two steps. At the first step, a thesaurus is created, whose terms weight polarities are calculated depending on the term occurrences in the training set or on the weights of related thesaurus terms. At the second step, the thesaurus is used to compute the features of words from texts and to classify texts by the algorithm SVM or Naive Bayes. In experiments with text corpora BBCSport, Reuters, PubMed and the corpus of articles about American immigrants, the authors varied the types of thesaurus relations that are involved in the classification and the degree of their use. The results of the experiments make it possible to evaluate the efficiency of the application of thesaurus relations for classification of raw texts and to determine under what conditions certain relationships affect more or less. In particular, the most useful thesaurus connections are synonymous and hierarchical, as they provide a better quality of classification. Цель данной статьи — проанализировать, насколько эффективно могут применяться различные типы тезаурусных связей в задачах классификации текстов. Основой исследования является автоматически сгенерированный тезаурус предметной области, содержащий три типа связей: синонимические, иерархические и ассоциативные. Для генерации тезауруса используется гибридный метод, основанный на нескольких лингвистических и статистических алгоритмах выделения семантических связей и позволяющий создать тезаурус с достаточно большим числом терминов и связей между ними. Авторы рассматривают две задачи: тематическая классификация текстов и классификация больших новостных статей по тональности. Для решения каждой из них авторами были использованы два подхода, каждый из которых дополняет стандартные алгоритмы процедурой, применяющей связи тезауруса для определения семантических особенностей текстов. Подход к тематической классификации включает в себя стандартный алгоритм BM25 вида «обучение без учителя» и процедуру, использующую синонимические и иерархические связи тезауруса предметной области. Подход к классификации по тональности состоит из двух шагов. На первом шаге создается тезаурус, тональные веса терминов которого считаются в зависимости от частоты встречаемости в обучаемой выборке или от веса соседей по тезаурусу. На втором шаге тезаурус применяется для вычисления признаков слов из текстов и классификации текстов методом опорных векторов или наивным байесовским классификатором. В экспериментах с корпусами BBCSport, Reuters, PubMed и корпусом статей об американских иммигрантах авторы варьировали типы связей, которые участвуют в классификации, и степень их использования. Результаты экспериментов позволяют оценить эффективность применения тезаурусных связей для классификации текстов на естественном языке и определить, при каких условиях те или иные связи имеют большую значимость. В частности, наиболее полезными тезаурусными связями оказались синонимические и иерархические, так как они обеспечивает лучшее качество классификации.

The Palgrave Handbook of Digital Russia Studies

This open access handbook presents a multidisciplinary and multifaceted perspective on how the ‘digital’ is simultaneously changing Russia and the research methods scholars use to study Russia. It provides a critical update on how Russian society, politics, economy, and culture are reconfigured in the context of ubiquitous connectivity and accounts for the political and societal responses to digitalization. In addition, it answers practical and methodological questions in handling Russian data and a wide array of digital methods. The volume makes a timely intervention in our understanding of the changing field of Russian Studies and is an essential guide for scholars, advanced undergraduate and graduate students studying Russia today