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Information RetrievalMotivationSlide 3Slide 4Slide 5Recent History of IRSlide 7Slide 8Slide 9Slide 10Information RetrievalConcerned with the:• Representation of• Storage of• Organization of, and• Access toinformation items.Motivation•Focus is on the user information need•Example 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)•Data retrieval–Task: which docs contain a set ofkeywords? (think database)–Well defined semantics–A single erroneous object implies failure!•Information retrieval–Task: get information about a subjector topic – task is user’s task rather than system’s task–Semantics are frequently loose–Errors are unavoidable and tolerated•IR system:–Interpret contents of information items–Generate a ranking which reflects relevance–Notion of relevance is most importantData vs. Information RetrievalBrief History of IRIR began with human systemsInformationCollections–Indexed–Searched–Selectedby humansBrief History of IR•IR as a CS field (80s & early 90s):–classification andcategorization–systems and languages–user interfacesand visualization Still, area was seen as of narrow interestRecent History of IRAdvent of the Web changed this perception–universal repositoryof knowledge –free (low cost)universal access–no editorial board–many problems:IR seen as key to finding the solutions!Increased capability for sharing personal collections of text and other mediaUser Activity in Information Tasks•The User Task–Retrieval•information or data•precise request, purposeful–Browsing•glancing around•navigation through associationsRetrievalBrowsingDatabaseWorking with Text•Logical view of the documents•Document representation viewed as a continuum from unprocessed text to a representation of documents’ semantic contentstructureAccentsspacingstopwordsNoungroupsstemmingManual indexingDocsstructure Full text Index termsWorking with Other MediaRetrieval of other media is by:–Similarity with example–Human attached metadata–Automatically assigned metadataUserInterface Content Processing & OperationsQuery OperationsIndexingSearchingRankingIndexContentqueryuser needuser feedbackranked docs retrieved docslogical viewlogical viewinverted fileDB Manager ModuleContent DatabaseContentThe Retrieval


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TAMU CSCE 315 - ir-intro

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