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Acceso a la información mediante exploración de sintagmas

III Jornadas de Bibliotecas Digitales El Escorial, 2002. Acceso a la información mediante exploración de sintagmas. Anselmo Peñas , Julio Gonzalo y Felisa Verdejo Dpto. Lenguajes y Sistemas Informáticos UNED. Overview. Motivation: problems in query formulation Hand-crafted approaches

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Acceso a la información mediante exploración de sintagmas

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  1. III Jornadas de Bibliotecas Digitales El Escorial, 2002 Acceso a la información medianteexploración de sintagmas Anselmo Peñas, Julio Gonzalo y Felisa Verdejo Dpto. Lenguajes y Sistemas Informáticos UNED

  2. Overview • Motivation: problems in query formulation • Hand-crafted approaches • Controlled vocabularies • Automatic approaches • Pure string processing • Automatic terminology extraction • Website Term Browser • Conclusions

  3. Formulation Query Refinement Search engine Document ranking Docs. Precise information needs Information need Help users to express and precise their information needs • Vague need • User doesn’t know exactly what he is looking for • Broad need • Compile or summarize pieces of information around a topic Users develop strategies without system assistance

  4. Information need Formulation Query Refinement Search engine Document ranking Docs. Language barriers Help users to overcome language barriers • Specific domain terminology • Find appropriate wording • Translinguality • Information available only in a foreign language • Natural Language characteristics • Lexical ambiguity • Terminology variation

  5. Controlled vocabularies indexing & browsing Terminology General approaches Information Retrieval

  6. Controlled vocabularies Problems • Construction & management (high cost) • Indexing • Manual keyword assessment • Errors in automatic keyword assessment • Domain specific • New domain needs a new thesaurus • Specialist oriented (know preferred descriptors) • Less specialized audience get poorer results

  7. Controlled vocabularies indexing & browsing String Processing Terminology Free text indexing General approaches Information Retrieval

  8. Search Free text searching • Help users to express and precise their information needs? • Help users to overcome language barriers?

  9. Keyphrase navigation (Phrasier) Controlled vocabularies indexing & browsing String Processing Terminology Free text indexing Phrase indexing & browsing (Phind) General approaches Information Retrieval

  10. “Keyphrase” navigation (Jones 1999) • Automatic extraction and assessment of 10 “keyphrases” to each document (KEA, Frank 1999) • Navigation between documents that share “keyphrases” Problems • No translinguality • No terminology variation

  11. Problems • No translinguality • No terminology variation

  12. Objectives • Develop a model • to help users to express and precise their information needs • to help users to overcome language barriers • Bringing to users the collection terminology • Morpho-syntactic, semantic & translingual variations • Without needs of thesauri construction • Establish an appropriate evaluation framework Website Term Browser

  13. Keyphrase navigation (Phrasier) Controlled vocabularies indexing & browsing String Processing Terminology Free text indexing Terminology Retrieval & Term browsing (WTB) Phrase indexing & browsing (Phind) Disambiguation Conceptual indexing Automatic Terminology Extraction Proposed approach Information Retrieval Natural Language Processing

  14. Terminology Retrieval From Automatic Terminology Extraction... Obtain lists of terms relevant for a specific domain • Term Extraction • Term Weighting • Term Selection ... to Terminology Retrieval Retrieve terms relevant for an information need • User query points the relevant terms • No terminology lists truncation • Favor recall relaxing term extraction patterns ... & Browsing • Navigate through relevant terminology • Access information from retrieved terms • Bridge the gap between query and collection vocabularies • Cross-Language

  15. Query in Spanish Hierarchy of terms Ranking of documents English Spanish Catalan

  16. Semantic variations Translingual variation Morpho-syntactic variations (permutation, insertion)

  17. Usefulness of Term Browsing • 2000 session logs in UNED.es comparing: • - Use of term area from WTB • - Use of document area from Google

  18. Conclusions Browsing of phrases and terminology • User oriented approach • Interaction over terminological information • Intermediate way between free-searching and thesaurus-guided searching • Without needs of thesaurus construction Website term Browser • Brings to users the collection terminology • Morpho-syntactic & semantic variations • Translinguality Evaluation • Users appreciate Term Browsing • WTB phrasal information can substantially complement the document ranking provided by the search engines

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