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Recuperação de Informação

Recuperação de Informação. Cap. 01: Introdução 21 de Fevereiro de 1999 Berthier Ribeiro-Neto. Motivation. IR: representation, storage, organization of, and access to information items Focus is on the user information need User information need:

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Recuperação de Informação

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  1. Recuperação de Informação Cap. 01: Introdução 21 de Fevereiro de 1999 Berthier Ribeiro-Neto

  2. Motivation • IR: representation, storage, organization of, and access to information items • Focus is on the user information need • User information need: • Find all docs containing information on college tennis teams which: (1) are maintained by a USA university and (2) participate in the NCAA tournament. • Emphasis is on the retrieval of information (not data)

  3. Motivation • Data retrieval • which docs contain a set of keywords? • Well defined semantics • a single erroneous object implies failure! • Information retrieval • information about a subject or topic • semantics is frequently loose • small errors are tolerated • IR system: • interpret contents of information items • generate a ranking which reflects relevance • notion of relevance is most important

  4. Motivation • IR at the center of the stage • IR in the last 20 years: • classification and categorization • systems and languages • user interfaces and visualization • Still, area was seen as of narrow interest • Advent of the Web changed this perception once and for all • universal repository of knowledge • free (low cost) universal access • no central editorial board • many problems though: IR seen as key to finding the solutions!

  5. Basic Concepts Retrieval Database Browsing • The User Task • Retrieval • information or data • purposeful • Browsing • glancing around • F1; cars, Le Mans, France, tourism

  6. structure Full text Index terms Basic Concepts • Logical view of the documents • Document representation viewed as a continuum: logical view of docs might shift Accents spacing Noun groups Manual indexing Docs stopwords stemming structure

  7. Text User Interface 4, 10 user need Text Text Operations 6, 7 logical view logical view Query Operations DB Manager Module Indexing user feedback 5 8 inverted file query Searching Index 8 retrieved docs Text Database Ranking ranked docs 2 The Retrieval Process

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