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(Information Retrieval)2003. 9. 24.
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Information Retrieval Data retrieval vs. Information
retrieval
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What is IR?
Information Retrieval is a science which deals with the
knowledge representation, storage, organization and access of
information items.
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Need for Information Retrieval ? ?Index, search ? ? ?
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NLM and Medline10 million articles3,500 journals since
1966PubMed, Internet Grateful Medhttp://www.nlm.nih.gov
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IR InternetSearch EngineVocabulary SystemInformation
ModelingFiltering and Classification Natural Language
Processing.
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InternetTCP/IP networkpublic(not free, but open to
everyone)carrier of electronic mailconvenient to get free
SWterabytes of informationdynamic rerouting
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Telephone network
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?Another network
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ARPAnet TCP/IP
Network in early stage
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Protocolrules of behavior
: : TCP/IP2 widely used network protocols : computer network 100
TCP/IP
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Internet AddressNetwork Host 32 bit8 ~ 24 bit
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Internet Classes
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E-mail [email protected]
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URL
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Hypertext
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DNSDomain Name System(DNS) IP
www.kyobobook.co.kr 203.112.118.101www.cnn.com
198.137.240.92
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Search engine News group Mailing list
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Internet Search Enginewww.yahoo.com
www.yahoo.co.krwww.altavista.comwww.altavista.co.krwww.excite.comwww.lycos.com,
www.lycos.co.kr
www.dreamwiz.comwww.naver.com
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Internet Search Engine
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() . . . () . 1~2 .
. . .
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AND searchSearch for Monet AND RenoirSearch for +Monet
+RenoirSearch for Monet RenoirAll the words option
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OR searchSearch for UPS U.P.S.Search for UPS OR U.P.S.Search for
UPS U.P.SAny of the Words option
foreign policy vs foreign policy
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NOT searchSearch for bugs life -antsSearch for bugs life NOT
antsSearch for bugs life AND NOT ants
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Near SearchKorea NEAR climateAltavista (advanced search)two
terms within 10 wordsKorea NEAR climateLycos (advanced search)two
terms within 25 words
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USENET
- USENET system - news group USENET news server in SNUnews
serverin Melbourne
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Newsgroup Search Engine
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Mailing list automatic mailing programs
LISTSERVMajordomocomputer & privacytravel, weather
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IR Modeling
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IR stepsText processingIndexinginverted filesignature
fileOrganization in DBQuery processingEvaluation
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Information-Retrieval
ProcessContentDatabaseInformationNeedQueryResultIndexingQueryFormulationRetrievalEvaluationRefinement
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Indexing
Processdocumentaccentspacingstopwordnoungroupstemmingautomaticor
manualindexingstructurerecognitionfull textindex terms
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Classification of IRUser
TaskRetrieval:AdhocFilteringBrowsingClassic
ModelsbooleanvectorprobabilisticStructured Modelsnon-overlapping
listsproximal nodesBrowsingFlatStructure GuidedHypertextSet
TheoreticFuzzyExtended BooleanAlgebraicGeneralized VectorLat.
Semantic IndexNeural NetworkProbabilisticInference NetworkBelief
Network
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Boolean Modelquery can be written in disjunctive normal formq =
ka (kb kc)qdnf = (1,1,1) (1,1,0) (1,0,0)KaKcKb
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Vector Model and Weight functionK = {, 2000cc, , , , kt}D1 =
{20, 20, 11, 5, ,5}D2 = {20, 18, 12, 4, , 5}D30 = {0, 20, 12, 3,
,9}weight terms are assumed to be mutually independent !
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Boolean vs. Vector modelPetroleum Mexico Oil Texas Refinery
Ship
(1 1 1 0 1 0)
(2.8 1.6 3.5 3 3.1 1)Boolean
Vector
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Retrieval IssuesIndexinginverted fileRankingrelevance
rankingchronology rankingDisplay(aspirin, prevention)(prevention,
)(aspirin, attack, heat)
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: 27750177 : 20022777035 : RC102: Brain CT (Pre contrast) :
Infarction Of Posterior Cerebral Artery Territory : 2002-08-02 :
BRAIN MRI + MRA [Finding] PVWM UBO underlying SVD . Left thalamus
occipital lobe patchy high signalintensity FLAIR image . T1WI iso
signal intensity portion Radiology ResultsInverted FileSignificant
words onlyIndexing with Inverted File
WORDDPWabort1,5aberrant 3brain7,3portion4,8topology5,8
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Evaluation of IRRecall ( ) Precision
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Word based indexing Contextmeaning is affected by meaning of
other wordshigh, blood, pressurelow pressure at high altitude
increase red blood cellPolysemylead vs leadSynonymyhypertension vs.
high blood pressureGranularityantibiotics, penicillinFocus of
ContentKey word vs Plain word
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The End
