Automatic text summarization

V této práci jsou představeny základní metody využívané v automatické sumarizaci textu a genetických algoritmech. Dále je zde navržen systém automatické sumarizace založený na grafových strukturách a Markovských řetězcích, který byl rovněž implementován a řádně otestován. Práce se dále zabývá učením správného nastavení vah důležitosti jednotlivých metod používaných v sumarizaci pomocí naivního přístupu a genetických algoritmů, které byly rovněž naimplementovány, včetně možnosti paralelního zpracovávání a využití cache pro zrychlení systému, a řádně otestovány.This work presents the basic methods used in automatic text summarization and genetic algorithms. Furthermore, system of automatic summarization based on graph structures and Markov chains was designed, implemented and properly tested. This study also discusses learning of proper setting of importance weights of individual methods used in summarization by naive approach and genetic algorithms, which were also implemented and properly tested. System also includes possibility of parallel processing and use of caching to speed up its process

Automatic text summarization

Automatic summarization is the procedure of decreasing the content of a document with a machine (computer) program so as to make a summary that holds the most critical sentences of the text file (document). Extracting summary from the document is a difficult task for human beings. Therefore to generate summary automatically has to facilitate several challenges; as the system automates it can only extract the required information from the original document. As the issue of information overload has grown - trouble has been initiated, and as the measure of data has extended, so has eagerness to customize it. It is uncommonly troublesome for individuals to physically condense broad reports of substance. Automatic Summarization systems may be classified into extractive and abstractive summary. An extractive summary method involves selecting indispensable sentences from the record and interfacing them into shorter structure. The vitality of sentences chosen is focused around factual and semantic characteristics of sentences. Extractive method work by selecting a subset of existing words, or sentences in the text file (content document) to produce the summary of input text file. The looking of important data from a huge content document is exceptionally difficult occupation for the user consequently to programmed concentrate the imperative information or summary of the content record. This summary helps the users to reduce time instead Of reading the whole text document and it provide quick knowledge from the large text file. The extractive summarization are commonly focused around techniques for sentence extraction to blanket the set of sentences that are most important for the general understanding of a given text file. In frequency based technique, obtained summary makes more meaning. But in k-means clustering due to out of order extraction, summary might not make sense

Aplikasi Automatic Text Summarizer

The background of this research is information overload which is an effect of ease of information manipulation, storage and distribution. Massive amount of text documents available causes a decline in effectivity and efficiency of an individual when using information. Automatic Text Summarization can solve information overload by producing text document summaries. Purpose of this research is to create an Automatic Text Summarization algorithm and its implementation to create summaries of important information from text documents faster and can satisfy users' needs of relevant and consistent summaries. The algorithm is based on sentence features scoring and Genetic Algorithm for determining sentence feature weights. Implementation consists of training phase (read text input, pre-summarization, summarization, and Genetic Algorithm to produce learned sentence feature weights) and testing phase (read text input, pre-summarization, summarization, and saving summary). The algorithm is evaluated by calculating summarization speed, precision, recall, F-measure, and subjective evaluation. The results are Automatic Text Summarization algorithm which is able to text documents by extracting important sentences which represent contents of original text documents. Conclusions of this research are Automatic Text Summarization algorithm can create extractive summaries which represent important information from a single document in Indonesian with faster summarization speed compared to manual process

Automatic Text Summarization

Writing text was one of the first ever methods used by humans to represent their knowledge. Text can be of different types and have different purposes. Due to the evolution of information systems and the Internet, the amount of textual information available has increased exponentially in a worldwide scale, and many documents tend to have a percentage of unnecessary information. Due to this event, most readers have difficulty in digesting all the extensive information contained in multiple documents, produced on a daily basis. A simple solution to the excessive irrelevant information in texts is to create summaries, in which we keep the subject’s related parts and remove the unnecessary ones. In Natural Language Processing, the goal of automatic text summarization is to create systems that process text and keep only the most important data. Since its creation several approaches have been designed to create better text summaries, which can be divided in two separate groups: extractive approaches and abstractive approaches. In the first group, the summarizers decide what text elements should be in the summary. The criteria by which they are selected is diverse. After they are selected, they are combined into the summary. In the second group, the text elements are generated from scratch. Abstractive summarizers are much more complex so they still need a lot of research, in order to represent good results. During this thesis, we have investigated the state of the art approaches, implemented our own versions and tested them in conventional datasets, like the DUC dataset. Our first approach was a frequency­based approach, since it analyses the frequency in which the text’s words/sentences appear in the text. Higher frequency words/sentences automatically receive higher scores which are then filtered with a compression rate and combined in a summary. Moving on to our second approach, we have improved the original TextRank algorithm by combining it with word embedding vectors. The goal was to represent the text’s sentences as nodes from a graph and with the help of word embeddings, determine how similar are pairs of sentences and rank them by their similarity scores. The highest ranking sentences were filtered with a compression rate and picked for the summary. In the third approach, we combined feature analysis with deep learning. By analysing certain characteristics of the text sentences, one can assign scores that represent the importance of a given sentence for the summary. With these computed values, we have created a dataset for training a deep neural network that is capable of deciding if a certain sentence must be or not in the summary. An abstractive encoder­decoder summarizer was created with the purpose of generating words related to the document subject and combining them into a summary. Finally, every single summarizer was combined into a full system. Each one of our approaches was evaluated with several evaluation metrics, such as ROUGE. We used the DUC dataset for this purpose and the results were fairly similar to the ones in the scientific community. As for our encoder­decode, we got promising results.O texto é um dos utensílios mais importantes de transmissão de ideias entre os seres humanos. Pode ser de vários tipos e o seu conteúdo pode ser mais ou menos fácil de interpretar, conforme a quantidade de informação relevante sobre o assunto principal. De forma a facilitar o processamento pelo leitor existe um mecanismo propositadamente criado para reduzir a informação irrelevante num texto, chamado sumarização de texto. Através da sumarização criam­se versões reduzidas do text original e mantém­se a informação do assunto principal. Devido à criação e evolução da Internet e outros meios de comunicação, surgiu um aumento exponencial de documentos textuais, evento denominado de sobrecarga de informação, que têm na sua maioria informação desnecessária sobre o assunto que retratam. De forma a resolver este problema global, surgiu dentro da área científica de Processamento de Linguagem Natural, a sumarização automática de texto, que permite criar sumários automáticos de qualquer tipo de texto e de qualquer lingua, através de algoritmos computacionais. Desde a sua criação, inúmeras técnicas de sumarização de texto foram idealizadas, podendo ser classificadas em dois tipos diferentes: extractivas e abstractivas. Em técnicas extractivas, são transcritos elementos do texto original, como palavras ou frases inteiras que sejam as mais ilustrativas do assunto do texto e combinadas num documento. Em técnicas abstractivas, os algoritmos geram elementos novos. Nesta dissertação pesquisaram­se, implementaram­se e combinaram­se algumas das técnicas com melhores resultados de modo a criar um sistema completo para criar sumários. Relativamente às técnicas implementadas, as primeiras três são técnicas extractivas enquanto que a ultima é abstractiva. Desta forma, a primeira incide sobre o cálculo das frequências dos elementos do texto, atribuindo­se valores às frases que sejam mais frequentes, que por sua vez são escolhidas para o sumário através de uma taxa de compressão. Outra das técnicas incide na representação dos elementos textuais sob a forma de nodos de um grafo, sendo atribuidos valores de similaridade entre os mesmos e de seguida escolhidas as frases com maiores valores através de uma taxa de compressão. Uma outra abordagem foi criada de forma a combinar um mecanismo de análise das caracteristicas do texto com métodos baseados em inteligência artificial. Nela cada frase possui um conjunto de caracteristicas que são usadas para treinar um modelo de rede neuronal. O modelo avalia e decide quais as frases que devem pertencer ao sumário e filtra as mesmas através deu uma taxa de compressão. Um sumarizador abstractivo foi criado para para gerar palavras sobre o assunto do texto e combinar num sumário. Cada um destes sumarizadores foi combinado num só sistema. Por fim, cada uma das técnicas pode ser avaliada segundo várias métricas de avaliação, como por exemplo a ROUGE. Segundo os resultados de avaliação das técnicas, com o conjunto de dados DUC, os nossos sumarizadores obtiveram resultados relativamente parecidos com os presentes na comunidade cientifica, com especial atenção para o codificador­descodificador que em certos casos apresentou resultados promissores

Automatic text summarization

Automatic text summarization has been a rapidly developing research area in natural language processing for the last 70 years. The development has progressed from simple heuristics to neural networks and deep learning. Both extractive and abstractive methods have maintained their interest to this day. In this thesis, we will research different methods on automatic text summarization and evaluate their capability to summarize text written in Finnish. We will build an extractive summarizer and evaluate how well it performs on Finnish news data. We also evaluate the goodness of the news data to see can it be used in the future to develop a deep learning based summarizer. The obtained ROUGE scores tell that the performance is not what is expected today from a generic summarizer. On the other hand, the qualitative evaluation reveals that the generated summaries often are more factual than the gold standard summaries in the data set

Text Summarization Techniques: A Brief Survey

In recent years, there has been a explosion in the amount of text data from a variety of sources. This volume of text is an invaluable source of information and knowledge which needs to be effectively summarized to be useful. In this review, the main approaches to automatic text summarization are described. We review the different processes for summarization and describe the effectiveness and shortcomings of the different methods.Comment: Some of references format have update

A Study of Realtime Summarization Metrics

Unexpected news events, such as natural disasters or other human tragedies, create a large volume of dynamic text data from official news media as well as less formal social media. Automatic real-time text summarization has become an important tool for quickly transforming this overabundance of text into clear, useful information for end-users including affected individuals, crisis responders, and interested third parties. Despite the importance of real-time summarization systems, their evaluation is not well understood as classic methods for text summarization are inappropriate for real-time and streaming conditions. The TREC 2013-2015 Temporal Summarization (TREC-TS) track was one of the first evaluation campaigns to tackle the challenges of real-time summarization evaluation, introducing new metrics, ground-truth generation methodology and dataset. In this paper, we present a study of TREC-TS track evaluation methodology, with the aim of documenting its design, analyzing its effectiveness, as well as identifying improvements and best practices for the evaluation of temporal summarization systems

Keyphrase Based Evaluation of Automatic Text Summarization

The development of methods to deal with the informative contents of the text units in the matching process is a major challenge in automatic summary evaluation systems that use fixed n-gram matching. The limitation causes inaccurate matching between units in a peer and reference summaries. The present study introduces a new Keyphrase based Summary Evaluator KpEval for evaluating automatic summaries. The KpEval relies on the keyphrases since they convey the most important concepts of a text. In the evaluation process, the keyphrases are used in their lemma form as the matching text unit. The system was applied to evaluate different summaries of Arabic multi-document data set presented at TAC2011. The results showed that the new evaluation technique correlates well with the known evaluation systems: Rouge1, Rouge2, RougeSU4, and AutoSummENG MeMoG. KpEval has the strongest correlation with AutoSummENG MeMoG, Pearson and spearman correlation coefficient measures are 0.8840, 0.9667 respectively.Comment: 4 pages, 1 figure, 3 table