Semantic Similarity from Natural Language and Ontology Analysis
Automatic text understanding requires knowledge and, so far, machines know only what we give or teach them. As a consequence, most natural language processing (NLP) tasks crucially rely on the existence of linguistic resources that encode information about language, be it of morphological, syntactic, or semantic nature. Such resources are typically acquired via two main approaches: the knowledge based approach, or top down, where information is manually curated by humans, and the corpus based approach, or bottom up, where information is automatically learned from corpora. Although the latter has gained ground during the last decade benefiting from the availability of large amounts of text and from increased computing capacities the former remains fundamental for it allows us to collect reliable, fine grained, and explicit information. Lexical knowledge bases (LKBs) also known as lexico semantic resources, provide information about words and potentially entities, and are at the core of knowledgebased approaches. They are widely used in a variety of NLP tasks (e.g. word sense disambiguation, information retrieval, and question answering) all the more so since their traditional limitations (i.e. lack of language and domain specific coverage) have recently started to fall. Indeed, beside the long established process of expert based resource creation (e.g. WordNet) Web technologies have enabled the collaborative, crowd based construction of resources (e.g. Wikipedia and Wiktionary) This contributed to significantly widen the scope of the available machine readable knowledge and, in the context of an already diverse landscape of LKBs, it encouraged and motivated even more the need to integrate different resources so as to make the best of them all. This book introduces linked lexical knowledge bases by giving an account of their foundations and presenting their main applications. Its target audience includes NLP practitioners or students who wish to better understand linked lexical knowledge bases, how they are built, and their typical usages and added value. The book is organized into eight chapters plus a preface, and is additionally put into perspective by a foreword (by Ido Dagan) that considers the history, recent evolution, and probable future directions of knowledge acquisition.
Computational Linguistics