計(jì)算機(jī)信息檢索

第二講計(jì)算機(jī)信息檢索ComputerizedInformationRetrieval

（工程碩士）

20112信息檢索詞匯（terms）Informationretrieval(IR)Informationaccess(obtain)Informationsearch(lookfor)Informationsearching(lookfor)Informationseeking(focusonusers,active)locatehit3信息檢索基本原理信息集合匹配與選擇需求集合特征化表示特征化表示41.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”52.主要檢索系統(tǒng)類(lèi)型聯(lián)機(jī)檢索(onlinesearch)

脫機(jī)檢索（offlinesearch）光盤(pán)檢索（CDsearch）網(wǎng)絡(luò)檢索（Interne/Websearch）全球數(shù)字圖書(shū)館系統(tǒng)（digitallibraryglobalsystem）6

通信網(wǎng)絡(luò)

聯(lián)機(jī)檢索中心

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

Theprocessoflocatingspecificpiecesofinfofromoneormoredatabasesthatresideonthecomputers(hosts).Thesearchisatrueinteractionbetweenyouandsearchsystem.

主機(jī)

Feature:interaction,realtimeremote,directInternetWAN微機(jī)7OnlinedatabasesFeatures

¨Atest-bedforearlyIRexperiments&development

¨The

showcaseofIRtechnology(e.g,relevanceretrieval)untiltheInternet,theWebbecamepopular

¨AlaboratoryforacquiringinformationretrievalskillsIRcapability

¨Coversvirtuallyeverytypeofdatabasestructures

¨Implementalldifferentretrievalmodelsandtechniques-----Hahn8OPAC

Features

¨AnextensionofMARCrecords

¨Aproductoflibraryautomation

¨Abibliographic

databaseoflibraryresourcesforaninstitutionatvariouslevels,e.g,local,regional,national

IRcapability

¨

Easytobrowse(resembleshelfstructure)

¨Basedonwell-establishedhierarchicaldatabasestructure¨Mayprovidesophisticatedsearchingcapabilitiesbutusersmaynotbenefitfromthem9光驅(qū)

微機(jī)

2.2光盤(pán)檢索(CDsearch)光盤(pán)單機(jī)檢索

檢索終端10局域網(wǎng)

服務(wù)器

光驅(qū)

LAN微機(jī)光盤(pán)聯(lián)機(jī)檢索(CD

online)

檢索終端11CD-ROMs

Features

¨OnlinedatabasesinCD-ROMmedium

¨Portability¨Cheaper&moreconvenientaccessuntiltheWebbecomesthegatewayforCD-ROMaccess

¨Noticeableprobleminupdatingthedatabase¨

HypertextorhypermediaisheavilyusedinCD-ROM

¨Becominganobsoletetechnology?IRcapabilities

¨Introducethe

browsingfeature

¨OtherIRtechniquessimilartothoseofonlinedatabases

¨

Slowerinspeed122.3網(wǎng)絡(luò)（Internet）信息檢索

Features

¨InitialintentionwasmoreonresourcessharingthanIR

¨Rapiddevelopmentandconstantimprovement

¨Wideusage

¨

Goodfor

presentinginformation,lesssofororganizingformation

IRcapability

¨Retrievalcapabilityisanaddition,notincludedintheoriginaldesignforthesystemexceptinthecaseofWAIS¨

Quality(unevenretrievalperformance)and

quantity

varyfromonetooltoanother¨

Replacingonlinesystemsandbecomingthelab&showcasefornew,advancedandsophisticatedIRtechniques13

3.數(shù)據(jù)庫(kù)的基本概念

3.1數(shù)據(jù)庫(kù)的定義

至少由一種文檔組成,能滿(mǎn)足特定目的的或特定數(shù)據(jù)處理系統(tǒng)需要的數(shù)據(jù)集合。14

3.2數(shù)據(jù)庫(kù)的類(lèi)型

1、參考數(shù)據(jù)庫(kù)書(shū)目數(shù)據(jù)(bibliographicdatabase)目錄數(shù)據(jù)庫(kù)(catalogdatabase)文摘索引數(shù)據(jù)庫(kù)(abstract/indexdatabase)指南數(shù)據(jù)庫(kù)(directorydatabase)15

2、源數(shù)據(jù)庫(kù)(sourcedatabase,databank)數(shù)值數(shù)據(jù)庫(kù)(numericdatabase)文本-數(shù)值數(shù)據(jù)庫(kù)(text-numericdatabase)屬性數(shù)據(jù)庫(kù)(propertydatabase)術(shù)語(yǔ)數(shù)據(jù)庫(kù)(terminologybank)全文數(shù)據(jù)庫(kù)(full-textdatabase)圖象數(shù)據(jù)庫(kù)(graphicdatabase)多媒體數(shù)據(jù)庫(kù)(multimediadatabase)

…163.3書(shū)目數(shù)據(jù)庫(kù)的結(jié)構(gòu)

文檔(file)

數(shù)據(jù)庫(kù)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(shū)目條目)17字段(field)

記錄的構(gòu)成單位

(條目中的一個(gè)信息項(xiàng))子字段(subfield)

字段的構(gòu)成單位184.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

19確定檢索點(diǎn)/詞

檢索課題用戶(hù)

主題分析選擇信息資源

選擇數(shù)據(jù)庫(kù)制定檢索式

計(jì)算機(jī)處理

結(jié)果檢驗(yàn)

索引詞表NY20

內(nèi)容Content

范圍Coverage

時(shí)效Currency

費(fèi)用Cost選庫(kù)的4C原則:21

檢索點(diǎn)(accesspoints):

主題subject

分類(lèi)classification

著者author

名稱(chēng)title

號(hào)碼code,coden...

22

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

如：漢語(yǔ)主題詞表(中文)LCSH詞表(英文)

23

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

24

4.3檢索方法

1、命令檢索(commandsearch)

算符(operator)

檢索式(query,profile，statement,formula)2、菜單檢索(menusearch)

提示選項(xiàng)填空

253、瀏覽檢索(browse，WIMP)hypertext，超文本鏈接(hyperlink)4、Web方式檢索(綜合應(yīng)用)

檢索方式：基本檢索(basic，easy,simple,quick)

高級(jí)檢索(advanced,expended,guided)

專(zhuān)家檢索(advanced,expert)

264.4檢索式的表達(dá)1、常用算符邏輯算符(booleanoperator)位置算符*截詞符字段符27

邏輯與

andsolar

and

energysolarenergy28

邏輯或

or