計(jì)算機(jī)檢索基礎(chǔ)課件

計(jì)算機(jī)信息檢索ComputerizedInformationRetrieval

（工程碩士）

2004.91信息檢索詞匯（terms）Informationretrieval(IR)Informationaccess(obtain)Informationsearch(lookfor)Informationsearching(lookfor)Informationseeking(focusonusers,active)locatehit21.信息檢索發(fā)展階段●手工操作(manual)●計(jì)算機(jī)化(computerized)●網(wǎng)絡(luò)化(networked)●智能化(intelligentized)●認(rèn)知化(cognized)What’ssearchinglike?“Findinganeedleinahaystack”3

通信網(wǎng)絡(luò)聯(lián)機(jī)檢索中心

檢索終端數(shù)據(jù)庫2.1聯(lián)機(jī)檢索(onlinesearch)

Theprocessoflocatingspecificpiecesofinfofromoneormoredatabasesthatresideonthecomputers(hosts).Thesearchisatrueinteractionbetweenyouandsearchsystem.

主機(jī)

Feature:interaction,realtimeremote,DirectInternetWAN微機(jī)5OnlinedatabasesFeatures

¨Atest-bedforearlyIRexperiments&development

¨TheshowcaseofIRtechnology(e.g,relevanceretrieval)untiltheInternet,theWebbecamepopular

¨AlaboratoryforacquiringinformationretrievalskillsIRcapability

¨Coversvirtuallyeverytypeofdatabasestructures

¨Implementalldifferentretrievalmodelsandtechniques-----Hahn6OPACs

Features

¨AnextensionofMARCrecords

¨Aproductoflibraryautomation

¨Abibliographicdatabaseoflibraryresourcesforaninstitutionatvariouslevels,e.g,local,regional,national

IRcapability

¨

Easytobrowse(resembleshelfstructure)

¨Basedonwell-establishedhierarchicaldatabasestructure¨Mayprovidesophisticatedsearchingcapabilitiesbutusersmaynotbenefitfromthem7

檢索終端局域網(wǎng)

服務(wù)器

光驅(qū)

LAN微機(jī)towerjukebox光盤聯(lián)機(jī)檢索(CD

online))9CD-ROMs

Features

¨OnlinedatabasesinCD-ROMmedium

¨Portability¨Cheaper&moreconvenientaccessuntiltheWebbecomesthegatewayforCD-ROMaccess

¨Noticeableprobleminupdatingthedatabase¨

HypertextorhypermediaisheavilyusedinCD-ROM

¨Becominganobsoletetechnology?IRcapabilities

¨Introducethe

browsingfeature

¨OtherIRtechniquessimilartothoseofonlinedatabases

¨

Slowerinspeed102.3網(wǎng)絡(luò)信息檢索（TheInternet）

Features

¨InitialintentionwasmoreonresourcessharingthanIR

¨Rapiddevelopmentandconstantimprovement

¨Wideusage

¨Goodforpresentinginformation,lesssofororganizingformation

IRcapability

¨

Retrievalcapabilityisanaddition,notincludedintheoriginaldesignforthesystemexceptinthecaseofWAIS¨Quality(unevenretrievalperformance)andquantityvaryfromonetooltoanother¨

Replacingonlinesystemsandbecomingthelab&showcasefornew,advancedandsophisticatedIRtechniques113.數(shù)據(jù)庫的基本概念

3.1數(shù)據(jù)庫的類型

(1)參考數(shù)據(jù)庫書目數(shù)據(jù)(bibliographicdatabase)目錄數(shù)據(jù)庫(catalogdatabase)文摘索引數(shù)據(jù)庫(abstract/indexdatabase) 指南數(shù)據(jù)庫(directorydatabase)

13(2)源數(shù)據(jù)庫(sourcedatabase,databank)數(shù)值數(shù)據(jù)庫（numericdatabase）文本-數(shù)值數(shù)據(jù)庫（text-numericdatabase）屬性數(shù)據(jù)庫（propertydatabase）術(shù)語數(shù)據(jù)庫（terminologybank）全文數(shù)據(jù)庫（full-textdatabase）圖象數(shù)據(jù)庫（graphicdatabase）多媒體數(shù)據(jù)庫（multimediadatabase）…143.2書目數(shù)據(jù)庫的結(jié)構(gòu)

文檔(file)

數(shù)據(jù)庫組織的基本形式記錄(record)

文檔的構(gòu)成單位

(對(duì)應(yīng)一個(gè)書目條目)154.計(jì)算機(jī)檢索基本方法

4.1.檢索策略

檢索步驟的科學(xué)安排

4.2.檢索步驟

17確定檢索點(diǎn)/詞

檢索課題用戶

主題分析選擇檢索系統(tǒng)

選擇數(shù)據(jù)庫制定檢索式

計(jì)算機(jī)處理

結(jié)果檢驗(yàn)

詞表NY18

內(nèi)容Content范圍Coverage時(shí)效Currency費(fèi)用Cost選庫的4C原則:19

檢索詞/語言:非規(guī)范詞(非受控詞自由詞) uncontrolled,free-term規(guī)范詞(受控詞)controlled

漢語主題詞表(中文)LCSH詞表(英文)

21

禁用詞:Stopwords:在記錄中出現(xiàn)的頻度太高，而不能用以檢索。如：AAREFOROFTHEWITHANASFORMONTHISWOULDANDBYINTHATTO,…22

4.3檢索方法

(1)命令檢索(commandsearch)算符(operator)檢索式(query,statement,formula,profile)(2)菜單檢索(menusearch)菜單選擇(menuselectio