7,081 research outputs found

    Entity-Oriented Search

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    This open access book covers all facets of entity-oriented search—where “search” can be interpreted in the broadest sense of information access—from a unified point of view, and provides a coherent and comprehensive overview of the state of the art. It represents the first synthesis of research in this broad and rapidly developing area. Selected topics are discussed in-depth, the goal being to establish fundamental techniques and methods as a basis for future research and development. Additional topics are treated at a survey level only, containing numerous pointers to the relevant literature. A roadmap for future research, based on open issues and challenges identified along the way, rounds out the book. The book is divided into three main parts, sandwiched between introductory and concluding chapters. The first two chapters introduce readers to the basic concepts, provide an overview of entity-oriented search tasks, and present the various types and sources of data that will be used throughout the book. Part I deals with the core task of entity ranking: given a textual query, possibly enriched with additional elements or structural hints, return a ranked list of entities. This core task is examined in a number of different variants, using both structured and unstructured data collections, and numerous query formulations. In turn, Part II is devoted to the role of entities in bridging unstructured and structured data. Part III explores how entities can enable search engines to understand the concepts, meaning, and intent behind the query that the user enters into the search box, and how they can provide rich and focused responses (as opposed to merely a list of documents)—a process known as semantic search. The final chapter concludes the book by discussing the limitations of current approaches, and suggesting directions for future research. Researchers and graduate students are the primary target audience of this book. A general background in information retrieval is sufficient to follow the material, including an understanding of basic probability and statistics concepts as well as a basic knowledge of machine learning concepts and supervised learning algorithms

    Linking named entities to Wikipedia

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    Natural language is fraught with problems of ambiguity, including name reference. A name in text can refer to multiple entities just as an entity can be known by different names. This thesis examines how a mention in text can be linked to an external knowledge base (KB), in our case, Wikipedia. The named entity linking (NEL) task requires systems to identify the KB entry, or Wikipedia article, that a mention refers to; or, if the KB does not contain the correct entry, return NIL. Entity linking systems can be complex and we present a framework for analysing their different components, which we use to analyse three seminal systems which are evaluated on a common dataset and we show the importance of precise search for linking. The Text Analysis Conference (TAC) is a major venue for NEL research. We report on our submissions to the entity linking shared task in 2010, 2011 and 2012. The information required to disambiguate entities is often found in the text, close to the mention. We explore apposition, a common way for authors to provide information about entities. We model syntactic and semantic restrictions with a joint model that achieves state-of-the-art apposition extraction performance. We generalise from apposition to examine local descriptions specified close to the mention. We add local description to our state-of-the-art linker by using patterns to extract the descriptions and matching against this restricted context. Not only does this make for a more precise match, we are also able to model failure to match. Local descriptions help disambiguate entities, further improving our state-of-the-art linker. The work in this thesis seeks to link textual entity mentions to knowledge bases. Linking is important for any task where external world knowledge is used and resolving ambiguity is fundamental to advancing research into these problems

    Approaches to implement and evaluate aggregated search

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    La recherche d'information agrĂ©gĂ©e peut ĂȘtre vue comme un troisiĂšme paradigme de recherche d'information aprĂšs la recherche d'information ordonnĂ©e (ranked retrieval) et la recherche d'information boolĂ©enne (boolean retrieval). Les deux paradigmes les plus explorĂ©s jusqu'Ă  aujourd'hui retournent un ensemble ou une liste ordonnĂ©e de rĂ©sultats. C'est Ă  l'usager de parcourir ces ensembles/listes et d'en extraire l'information nĂ©cessaire qui peut se retrouver dans plusieurs documents. De maniĂšre alternative, la recherche d'information agrĂ©gĂ©e ne s'intĂ©resse pas seulement Ă  l'identification des granules (nuggets) d'information pertinents, mais aussi Ă  l'assemblage d'une rĂ©ponse agrĂ©gĂ©e contenant plusieurs Ă©lĂ©ments. Dans nos travaux, nous analysons les travaux liĂ©s Ă  la recherche d'information agrĂ©gĂ©e selon un schĂ©ma gĂ©nĂ©ral qui comprend 3 parties: dispatching de la requĂȘte, recherche de granules d'information et agrĂ©gation du rĂ©sultat. Les approches existantes sont groupĂ©es autours de plusieurs perspectives gĂ©nĂ©rales telle que la recherche relationnelle, la recherche fĂ©dĂ©rĂ©e, la gĂ©nĂ©ration automatique de texte, etc. Ensuite, nous nous sommes focalisĂ©s sur deux pistes de recherche selon nous les plus prometteuses: (i) la recherche agrĂ©gĂ©e relationnelle et (ii) la recherche agrĂ©gĂ©e inter-verticale. * La recherche agrĂ©gĂ©e relationnelle s'intĂ©resse aux relations entre les granules d'information pertinents qui servent Ă  assembler la rĂ©ponse agrĂ©gĂ©e. En particulier, nous nous sommes intĂ©ressĂ©s Ă  trois types de requĂȘtes notamment: requĂȘte attribut (ex. prĂ©sident de la France, PIB de l'Italie, maire de Glasgow, ...), requĂȘte instance (ex. France, Italie, Glasgow, Nokia e72, ...) et requĂȘte classe (pays, ville française, portable Nokia, ...). Pour ces requĂȘtes qu'on appelle requĂȘtes relationnelles nous avons proposĂ©s trois approches pour permettre la recherche de relations et l'assemblage des rĂ©sultats. Nous avons d'abord mis l'accent sur la recherche d'attributs qui peut aider Ă  rĂ©pondre aux trois types de requĂȘtes. Nous proposons une approche Ă  large Ă©chelle capable de rĂ©pondre Ă  des nombreuses requĂȘtes indĂ©pendamment de la classe d'appartenance. Cette approche permet l'extraction des attributs Ă  partir des tables HTML en tenant compte de la qualitĂ© des tables et de la pertinence des attributs. Les diffĂ©rentes Ă©valuations de performances effectuĂ©es prouvent son efficacitĂ© qui dĂ©passe les mĂ©thodes de l'Ă©tat de l'art. DeuxiĂšmement, nous avons traitĂ© l'agrĂ©gation des rĂ©sultats composĂ©s d'instances et d'attributs. Ce problĂšme est intĂ©ressant pour rĂ©pondre Ă  des requĂȘtes de type classe avec une table contenant des instances (lignes) et des attributs (colonnes). Pour garantir la qualitĂ© du rĂ©sultat, nous proposons des pondĂ©rations sur les instances et les attributs promouvant ainsi les plus reprĂ©sentatifs. Le troisiĂšme problĂšme traitĂ© concerne les instances de la mĂȘme classe (ex. France, Italie, Allemagne, ...). Nous proposons une approche capable d'identifier massivement ces instances en exploitant les listes HTML. Toutes les approches proposĂ©es fonctionnent Ă  l'Ă©chelle Web et sont importantes et complĂ©mentaires pour la recherche agrĂ©gĂ©e relationnelle. Enfin, nous proposons 4 prototypes d'application de recherche agrĂ©gĂ©e relationnelle. Ces derniers peuvent rĂ©pondre des types de requĂȘtes diffĂ©rents avec des rĂ©sultats relationnels. Plus prĂ©cisĂ©ment, ils recherchent et assemblent des attributs, des instances, mais aussi des passages et des images dans des rĂ©sultats agrĂ©gĂ©s. Un exemple est la requĂȘte ``Nokia e72" dont la rĂ©ponse sera composĂ©e d'attributs (ex. prix, poids, autonomie batterie, ...), de passages (ex. description, reviews, ...) et d'images. Les rĂ©sultats sont encourageants et illustrent l'utilitĂ© de la recherche agrĂ©gĂ©e relationnelle. * La recherche agrĂ©gĂ©e inter-verticale s'appuie sur plusieurs moteurs de recherche dits verticaux tel que la recherche d'image, recherche vidĂ©o, recherche Web traditionnelle, etc. Son but principal est d'assembler des rĂ©sultats provenant de toutes ces sources dans une mĂȘme interface pour rĂ©pondre aux besoins des utilisateurs. Les moteurs de recherche majeurs et la communautĂ© scientifique nous offrent dĂ©jĂ  une sĂ©rie d'approches. Notre contribution consiste en une Ă©tude sur l'Ă©valuation et les avantages de ce paradigme. Plus prĂ©cisĂ©ment, nous comparons 4 types d'Ă©tudes qui simulent des situations de recherche sur un total de 100 requĂȘtes et 9 sources diffĂ©rentes. Avec cette Ă©tude, nous avons identifiĂ©s clairement des avantages de la recherche agrĂ©gĂ©e inter-verticale et nous avons pu dĂ©duire de nombreux enjeux sur son Ă©valuation. En particulier, l'Ă©valuation traditionnelle utilisĂ©e en RI, certes la moins rapide, reste la plus rĂ©aliste. Pour conclure, nous avons proposĂ© des diffĂ©rents approches et Ă©tudes sur deux pistes prometteuses de recherche dans le cadre de la recherche d'information agrĂ©gĂ©e. D'une cĂŽtĂ©, nous avons traitĂ© trois problĂšmes importants de la recherche agrĂ©gĂ©e relationnelle qui ont portĂ© Ă  la construction de 4 prototypes d'application avec des rĂ©sultats encourageants. De l'autre cĂŽtĂ©, nous avons mis en place 4 Ă©tudes sur l'intĂ©rĂȘt et l'Ă©valuation de la recherche agrĂ©gĂ©e inter-verticale qui ont permis d'identifier les enjeux d'Ă©valuation et les avantages du paradigme. Comme suite Ă  long terme de ce travail, nous pouvons envisager une recherche d'information qui intĂšgre plus de granules relationnels et plus de multimĂ©dia.Aggregated search or aggregated retrieval can be seen as a third paradigm for information retrieval following the Boolean retrieval paradigm and the ranked retrieval paradigm. In the first two, we are returned respectively sets and ranked lists of search results. It is up to the time-poor user to scroll this set/list, scan within different documents and assemble his/her information need. Alternatively, aggregated search not only aims the identification of relevant information nuggets, but also the assembly of these nuggets into a coherent answer. In this work, we present at first an analysis of related work to aggregated search which is analyzed with a general framework composed of three steps: query dispatching, nugget retrieval and result aggregation. Existing work is listed aside different related domains such as relational search, federated search, question answering, natural language generation, etc. Within the possible research directions, we have then focused on two directions we believe promise the most namely: relational aggregated search and cross-vertical aggregated search. * Relational aggregated search targets relevant information, but also relations between relevant information nuggets which are to be used to assemble reasonably the final answer. In particular, there are three types of queries which would easily benefit from this paradigm: attribute queries (e.g. president of France, GDP of Italy, major of Glasgow, ...), instance queries (e.g. France, Italy, Glasgow, Nokia e72, ...) and class queries (countries, French cities, Nokia mobile phones, ...). We call these queries as relational queries and we tackle with three important problems concerning the information retrieval and aggregation for these types of queries. First, we propose an attribute retrieval approach after arguing that attribute retrieval is one of the crucial problems to be solved. Our approach relies on the HTML tables in the Web. It is capable to identify useful and relevant tables which are used to extract relevant attributes for whatever queries. The different experimental results show that our approach is effective, it can answer many queries with high coverage and it outperforms state of the art techniques. Second, we deal with result aggregation where we are given relevant instances and attributes for a given query. The problem is particularly interesting for class queries where the final answer will be a table with many instances and attributes. To guarantee the quality of the aggregated result, we propose the use of different weights on instances and attributes to promote the most representative and important ones. The third problem we deal with concerns instances of the same class (e.g. France, Germany, Italy ... are all instances of the same class). Here, we propose an approach that can massively extract instances of the same class from HTML lists in the Web. All proposed approaches are applicable at Web-scale and they can play an important role for relational aggregated search. Finally, we propose 4 different prototype applications for relational aggregated search. They can answer different types of queries with relevant and relational information. Precisely, we not only retrieve attributes and their values, but also passages and images which are assembled into a final focused answer. An example is the query ``Nokia e72" which will be answered with attributes (e.g. price, weight, battery life ...), passages (e.g. description, reviews ...) and images. Results are encouraging and they illustrate the utility of relational aggregated search. * The second research direction that we pursued concerns cross-vertical aggregated search, which consists of assembling results from different vertical search engines (e.g. image search, video search, traditional Web search, ...) into one single interface. Here, different approaches exist in both research and industry. Our contribution concerns mostly evaluation and the interest (advantages) of this paradigm. We propose 4 different studies which simulate different search situations. Each study is tested with 100 different queries and 9 vertical sources. Here, we could clearly identify new advantages of this paradigm and we could identify different issues with evaluation setups. In particular, we observe that traditional information retrieval evaluation is not the fastest but it remains the most realistic. To conclude, we propose different studies with respect to two promising research directions. On one hand, we deal with three important problems of relational aggregated search following with real prototype applications with encouraging results. On the other hand, we have investigated on the interest and evaluation of cross-vertical aggregated search. Here, we could clearly identify some of the advantages and evaluation issues. In a long term perspective, we foresee a possible combination of these two kinds of approaches to provide relational and cross-vertical information retrieval incorporating more focus, structure and multimedia in search results
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