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Relevance Feedback. Limitations Must yield result within at most 3-4 iterations Users will likely terminate the process sooner User may get irritated at seeing same documents repeated after every iteration It has proven to increase the effectiveness of retrieval.

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relevance feedback
Relevance Feedback
  • Limitations
    • Must yield result within at most 3-4 iterations
    • Users will likely terminate the process sooner
    • User may get irritated at seeing same documents repeated after every iteration
  • It has proven to increase the effectiveness of retrieval
designing a relevance feedback system
Designing a Relevance Feedback System
  • Use positive or negative relevance judgments
  • Where to apply relevance judgments (query, profile, document, retrieval algorithm)
  • Term weight modification. E.g.,
    • Increase the weight for terms that appear in relevant docs
    • Add new terms found in relevant docs that are frequently mention in connection with query term
genetic algorithms
Genetic Algorithms
  • Several possible solutions are generated in parallel
  • The best few of these solutions is chosen and replicated, while the poor ones eliminated
  • Replicated solutions creates a breeding population, from which new solutions arise
  • The breeding is accomplished by by an exchange of some of the characteristics of the chosen solutions in a crossover operation
genetic algorithms cont
Genetic Algorithms (cont.)
  • Hill climbing is avoided by
    • Pursue multiple solutions in parallel, and discard the low hills
    • Introduce new characteristic values at low rate through mutation process (random exchange)
  • Relevance Feedback
    • Relieves the user of the burden of assigning term weights
      • Begins with no weights. Generates query variants by assigning term weights randomly
genetic algorithms cont5
Genetic Algorithms (cont.)
  • Query variants are vector of query term weights
  • Each query variant is used to search the documents in the database
  • Evaluate each variant with equation on pg. 226
  • The variants with highest value creating the most replications
  • The resulting breeding population is developed to the same size as the original population
natural language processing
Natural Language Processing
  • Focus on structure more than meaning, consequently problems are
    • Syntactic ambiguity e.g., they are visiting relatives
    • Deep structure of a sentence e.g., grace
    • May or may not be semantically correct e.g., Colorless green ideas sleep furiously
    • Syntactic rules do not apply to e.g., boolean queries
natural language processing cont
Natural Language Processing (cont.)
  • Semantic Analysis
    • Even more elusie e.g., red herring, carrying coals to Newcastle
  • Techniques for Semantic Analysis
    • Latent semantic indexing uses multidimensional scaling methods to identify concepts
    • Dialogue Analysis involves interaction that each time clarifies further what is to be retrieved
citation processing
Citation Processing
  • Use of cited documents to enhance the description of a primary document
  • Some use co-citation as a measure of document similarity I.e., number of papers that cite both
  • Bibliographic coupling, when two documents cite the same document
  • Design problems: Locating citations, interpretation, eliminate duplicate/useless,
hypertext links
Hypertext Links
  • Means of connecting 2 distinct pieces of text
  • Consists of an identifier and a pointer
  • Possibly aid retrieval by suggesting hyperlinks given in top ranked document retrieved
  • Do not follow links from linked documents
  • Information Filtering: Eliminate large segments of database from consideration
  • Passage Retrieval: Identifying relevant sections within a large document encyclopedia
image and sound processing
Image and Sound Processing
  • Techniques for evaluating and manipulating images directly
  • Voice recognition
  • Animation and sound: compare to those in libraries
  • Music can use style and then pattern matching