A Novel Approach Towards Automatic Text Summarization Using Lexical Chains

Text summarization is a process of extracting text by virtue of reduction of document contents while preserving the salient information intact. By using different set of parameters like position, format and type of sentences in an input text, frequency of words in a text etc., techniques have been developed. But the parameters vary depending on source of input texts. This in turn affects the performance of the algorithms. In this paper, we present a new method of automatic text summarization by making use of lexical cohesion in the text. Until now lexical chains have been used to model lexical cohesion. These lexical chains are sequences of words having semantic relations between them. In our proposed algorithm, we have used a modification of lexical chains to model the relationships that exist between words. DOI: 10.17762/ijritcc2321-8169.15081

NLP Driven Models for Automatically Generating Survey Articles for Scientific Topics.

This thesis presents new methods that use natural language processing (NLP) driven models for summarizing research in scientific fields. Given a topic query in the form of a text string, we present methods for finding research articles relevant to the topic as well as summarization algorithms that use lexical and discourse information present in the text of these articles to generate coherent and readable extractive summaries of past research on the topic. In addition to summarizing prior research, good survey articles should also forecast future trends. With this motivation, we present work on forecasting future impact of scientific publications using NLP driven features.PhDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113407/1/rahuljha_1.pd

Thematic Annotation: extracting concepts out of documents

Contrarily to standard approaches to topic annotation, the technique used in this work does not centrally rely on some sort of -- possibly statistical -- keyword extraction. In fact, the proposed annotation algorithm uses a large scale semantic database -- the EDR Electronic Dictionary -- that provides a concept hierarchy based on hyponym and hypernym relations. This concept hierarchy is used to generate a synthetic representation of the document by aggregating the words present in topically homogeneous document segments into a set of concepts best preserving the document's content. This new extraction technique uses an unexplored approach to topic selection. Instead of using semantic similarity measures based on a semantic resource, the later is processed to extract the part of the conceptual hierarchy relevant to the document content. Then this conceptual hierarchy is searched to extract the most relevant set of concepts to represent the topics discussed in the document. Notice that this algorithm is able to extract generic concepts that are not directly present in the document.Comment: Technical report EPFL/LIA. 81 pages, 16 figure

Automatic Concept Extraction in Semantic Summarization Process

The Semantic Web offers a generic infrastructure for interchange, integration and creative reuse of structured data, which can help to cross some of the boundaries that Web 2.0 is facing. Currently, Web 2.0 offers poor query possibilities apart from searching by keywords or tags. There has been a great deal of interest in the development of semantic-based systems to facilitate knowledge representation and extraction and content integration [1], [2]. Semantic-based approach to retrieving relevant material can be useful to address issues like trying to determine the type or the quality of the information suggested from a personalized environment. In this context, standard keyword search has a very limited effectiveness. For example, it cannot filter for the type of information, the level of information or the quality of information. Potentially, one of the biggest application areas of content-based exploration might be personalized searching framework (e.g., [3],[4]). Whereas search engines provide nowadays largely anonymous information, new framework might highlight or recommend web pages related to key concepts. We can consider semantic information representation as an important step towards a wide efficient manipulation and retrieval of information [5], [6], [7]. In the digital library community a flat list of attribute/value pairs is often assumed to be available. In the Semantic Web community, annotations are often assumed to be an instance of an ontology. Through the ontologies the system will express key entities and relationships describing resources in a formal machine-processable representation. An ontology-based knowledge representation could be used for content analysis and object recognition, for reasoning processes and for enabling user-friendly and intelligent multimedia content search and retrieval. Text summarization has been an interesting and active research area since the 60’s. The definition and assumption are that a small portion or several keywords of the original long document can represent the whole informatively and/or indicatively. Reading or processing this shorter version of the document would save time and other resources [8]. This property is especially true and urgently needed at present due to the vast availability of information. Concept-based approach to represent dynamic and unstructured information can be useful to address issues like trying to determine the key concepts and to summarize the information exchanged within a personalized environment. In this context, a concept is represented with a Wikipedia article. With millions of articles and thousands of contributors, this online repository of knowledge is the largest and fastest growing encyclopedia in existence. The problem described above can then be divided into three steps: • Mapping of a series of terms with the most appropriate Wikipedia article (disambiguation). • Assigning a score for each item identified on the basis of its importance in the given context. • Extraction of n items with the highest score. Text summarization can be applied to many fields: from information retrieval to text mining processes and text display. Also in personalized searching framework text summarization could be very useful. The chapter is organized as follows: the next Section introduces personalized searching framework as one of the possible application areas of automatic concept extraction systems. Section three describes the summarization process, providing details on system architecture, used methodology and tools. Section four provides an overview about document summarization approaches that have been recently developed. Section five summarizes a number of real-world applications which might benefit from WSD. Section six introduces Wikipedia and WordNet as used in our project. Section seven describes the logical structure of the project, describing software components and databases. Finally, Section eight provides some consideration..

Lexical Chaining and Word-Sense-Disambiguation

Lexical chains algorithms attempt to find sequences of words in a document that are closely related semantically. Such chains have been argued to provide a good indication of the topics covered by the document without requiring a deeper analysis of the text, and have been proposed for many NLP tasks. Different underlying lexical semantic relations based on WordNet have been used for this task. Since links in WordNet connect synsets rather than words, open word-sense disambiguation becomes a necessary part of any chaining algorithm, even if the intended application is not disambiguation. Previous chaining algorithms have combined the tasks of disambiguation and chaining by choosing those word senses that maximize chain connectivity, a strategy which yields poor disambiguation accuracy in practice. We present a novel probabilistic algorithm for finding lexical chains. Our algorithm explicitly balances the requirements of maximizing chain connectivity with the choice of probable word-senses. The algorithm achieves better disambiguation results than all previous ones, but under its optimal settings shifts this balance totally in favor of probable senses, essentially ignoring the chains. This model points to an inherent conflict between chaining and word-sensedisambiguation. By establishing an upper bound on the disambiguation potential of lexical chains, we show that chaining is theoretically highly unlikely to achieve accurate disambiguation. Moreover, by defining a novel intrinsic evaluation criterion for lexical chains, we show that poor disambiguation accuracy also implies poor chain accuracy. Our results have crucial implications for chaining algorithms. At the very least, they show that disentangling disambiguation from chaining significantly improves chaining accuracy. The hardness of all-words disambiguation, however, implies that finding accurate lexical chains is harder than suggested by the literature.Engineering and Applied Science

Text summarization using concept hierarchy

This dissertation aims to create new sentences to summarize text documents. In addition to generating new sentences, this project also generates new concepts and extracts key sentences to summarize documents. This project is the first research work that can generate new key concepts and can create new sentences to summarize documents. Automatic document summarization is the process of creating a condensed version of the document. The condensed version extracts the key contents from the original document. Most related research uses statistical methods that generate a summary based on word distribution in the document. In this dissertation, we create a summary based on concept distributions and concept hierarchies. We use Stanford parser as our syntax parser and ResearchCyc (Cyc) as our knowledge base. Words and phrases of a document are mapped into Cyc concepts. We introduce a unique concept propagation method to generate abstract concepts and use those abstract concepts for the summarization. This method has two advantages over the existing methods. One advantage is the use of multi-level upward propagation to solve the word sense disambiguation problem. The other is that the propagation process provides a method to produce generalized concepts. In the first part of the project, we generate a summary by extracting key concepts and key sentences from documents. We use Stanford parser to segment a document to sentences and to parse each sentence to words or phrases tagged with their part-of-speeches. We use Cyc commands to map those words and phrases to their corresponding Cyc concepts and increase the weights of those concepts. To handle word sense disambiguation and to create summarized concepts, we propagate the weight of the concepts upward along the Cyc concept hierarchy. Then, we extract the concepts with some of the highest weights to be the key concepts. To extract key sentences from the document, we weigh each sentence in the document based on the concept weight associated with the sentence. Then, we extract the sentences with some of the highest weights to summarize the document. In the second part of the project, we generate new sentences to summarize a document based on the generalized concepts. First, we extract the subject, predicate, and object from each sentence. Then, we create compatible matrices based on the compatibility between the subjects, predicates, and objects among sentences. Two terms are considered to be compatible if the following three conditions hold: the two terms are the same concept, one concept is the other concept\u27s immediate super class, or two concepts share the same immediate super class. From the compatible matrices, we build compatible clusters and finally generate new sentences for each compatible cluster. These newly generated sentences serve as a summary for the document. We have implemented and tested our approaches. The test results show that our approaches are viable and have great potential for future research

Multi Domain Semantic Information Retrieval Based on Topic Model

Over the last decades, there have been remarkable shifts in the area of Information Retrieval (IR) as huge amount of information is increasingly accumulated on the Web. The gigantic information explosion increases the need for discovering new tools that retrieve meaningful knowledge from various complex information sources. Thus, techniques primarily used to search and extract important information from numerous database sources have been a key challenge in current IR systems. Topic modeling is one of the most recent techniquesthat discover hidden thematic structures from large data collections without human supervision. Several topic models have been proposed in various fields of study and have been utilized extensively for many applications. Latent Dirichlet Allocation (LDA) is the most well-known topic model that generates topics from large corpus of resources, such as text, images, and audio.It has been widely used in many areas in information retrieval and data mining, providing efficient way of identifying latent topics among document collections. However, LDA has a drawback that topic cohesion within a concept is attenuated when estimating infrequently occurring words. Moreover, LDAseems not to consider the meaning of words, but rather to infer hidden topics based on a statisticalapproach. However, LDA can cause either reduction in the quality of topic words or increase in loose relations between topics. In order to solve the previous problems, we propose a domain specific topic model that combines domain concepts with LDA. Two domain specific algorithms are suggested for solving the difficulties associated with LDA. The main strength of our proposed model comes from the fact that it narrows semantic concepts from broad domain knowledge to a specific one which solves the unknown domain problem. Our proposed model is extensively tested on various applications, query expansion, classification, and summarization, to demonstrate the effectiveness of the model. Experimental results show that the proposed model significantly increasesthe performance of applications