《信息科学类专业英语》课件第21章

Lesson21IntroductiontoArtificialIntelligence

(第二十一课现代人工智能简介)

Vocabulary(词汇)ImportantSentences(重点句)Multiple-choiceQuestions(多选题)Problems(问题)

HumankindhasgivenitselfthescientificnameHomosapiens—manthewise—becauseourmentalcapacitiesaresoimportanttooureverydaylivesandoursenseofself.Thefieldofartificialintelligence,orAI,attemptstounderstandintelligententities.Thus,onereasontostudyitistolearnmoreaboutourselves.Butunlikephilosophyandpsychology,whicharealsoconcernedwithintelligence,AIstrivestobuildintelligententitiesaswellasunderstandthem.AnotherreasontostudyAIisthattheseconstructedintelligententitiesareinterestingandusefulintheirownright.AIhasproducedmanysignificantandimpressiveproductsevenatthisearlystageinitsdevelopment.Althoughnoonecanpredictthefutureindetail,itisclearthatcomputerswithhuman-levelintelligence(orbetter)wouldhaveahugeimpactonoureverydaylivesandonthefuturecourseofcivilization.[1]

AIaddressesoneoftheultimatepuzzles.Howisitpossibleforaslow,tinybrain,whetherbiologicalorelectronic,toperceive,understand,predict,andmanipulateaworldfarlargerandmorecomplicatedthanitself?Howdowegoaboutmakingsomethingwiththoseproperties?Thesearehardquestions,butunlikethesearchforfaster-than-lighttraveloranantigravitydevice,theresearcherinAIhassolidevidencethatthequestispossible.Alltheresearcherhastodoislookinthemirrortoseeanexampleofanintelligentsystem.

AIisoneofthenewestdisciplines.Itwasformallyinitiatedin1956,whenthenamewascoined,althoughatthatpointworkhadbeenunderwayforaboutfiveyears.Alongwithmoderngenetics,itisregularlycitedasthe“fieldIwouldmostliketobein”byscientistsinotherdisciplines.AstudentinphysicsmightreasonablyfeelthatallthegoodideashavealreadybeentakenbyGalileo,Newton,Einstein,andtherest,andthatittakesmanyyearsofstudybeforeonecancontributenewideas.AI,ontheotherhand,stillhasopeningsforafull-timeEinstein.

AIcurrentlyencompassesahugevarietyofsubfields,fromgeneral-purposeareassuchasperceptionandlogicalreasoning,tospecifictaskssuchasplayingchess,provingmathematicaltheorems,writingpoetry,anddiagnosingdiseases.Often,scientistsinotherfieldsmovegraduallyintoartificialintelligence,wheretheyfindthetoolsandvocabularytosystematizeandautomatetheintellectualtasksonwhichtheyhavebeenworkingalltheirlives.[2]Similarly,workersinAIcanchoosetoapplytheirmethodstoanyareaofhumanintellectualendeavor.Inthissense,itistrulyauniversalfield.1WhatisAI?

WehavenowexplainedwhyAIisexciting,butwehavenotsaidwhatitis.Definitionsofartificialintelligenceaccordingtoeightrecenttextbooksareshowninthetablebelow.Thesedefinitionsvaryalongtwomaindimensions.Theonesontopareconcernedwiththoughtprocessesandreasoning,whereastheonesonthebottomaddressbehavior.Also,thedefinitionsontheleftmeasuresuccessintermsofhumanperformance,whereastheonesontherightmeasureagainstanidealconceptofintelligence,whichwewillcallrationality.Asystemisrationalifitdoestherightthing.Table.1AIDefinitionVaryalongtwomaindimensions

Thisgivesusfourpossiblegoalstopursueinartificialintelligence:

Historically,allfourapproacheshavebeenfollowed.Asonemightexpect,atensionexistsbetweenapproachescenteredaroundhumansandapproachescenteredaroundrationality.Ahuman-centeredapproachmustbeanempiricalscience,involvinghypothesisandexperimentalconfirmation.Arationalistapproachinvolvesacombinationofmathematicsandengineering.Peopleineachgroupsometimescastaspersionsonworkdoneintheothergroups,butthetruthisthateachdirectionhasyieldedvaluableinsights.Letuslookateachinmoredetail.2ActingHumanly:theTuringTestApproach

TheTuringTest,proposedbyAlanTuring(Turing,1950),wasdesignedtoprovideasatisfactoryoperationaldefinitionofintelligence.Turingdefinedintelligentbehaviorastheabilitytoachievehuman-levelperformanceinallcognitivetasks,sufficienttofoolaninterrogator.Roughlyspeaking,thetestheproposedisthatthecomputershouldbeinterrogatedbyahumanviaateletype,andpassesthetestiftheinterrogatorcannottellifthereisacomputerorahumanattheotherend.Programmingacomputertopassthetestprovidesplentytoworkon.Thecomputerwouldneedtopossessthefollowingcapabilities:

naturallanguageprocessingtoenableittocommunicatesuccessfullyinEnglish(orsomeotherhumanlanguage);

knowledgerepresentationtostoreinformationprovidedbeforeorduringtheinterrogation;

automatedreasoningtousethestoredinformationtoanswerquestionsandtodrawnewconclusions;

machinelearningtoadapttonewcircumstancesandtodetectandextrapolatepatterns.

Turing’stestdeliberatelyavoideddirectphysicalinteractionbetweentheinterrogatorandthecomputer,becausephysicalsimulationofapersonisunnecessaryforintelligence.[3]However,theso-calledtotalTuringTestincludesavideosignalsothattheinterrogatorcantestthesubject’sperceptualabilities,aswellastheopportunityfortheinterrogatortopassphysicalobjects“throughthehatch.”TopassthetotalTuringTest,thecomputerwillneed

computervisiontoperceiveobjects,and

roboticstomovethemabout.

WithinAI,therehasnotbeenabigefforttotrytopasstheTuringtest.TheissueofactinglikeahumancomesupprimarilywhenAIprogramshavetointeractwithpeople,aswhenanexpertsystemexplainshowitcametoitsdiagnosis,oranaturallanguageprocessingsystemhasadialoguewithauser.Theseprogramsmustbehaveaccordingtocertainnormalconventionsofhumaninteractioninordertomakethemselvesunderstood.Theunderlyingrepresentationandreasoninginsuchasystemmayormaynotbebasedonahumanmodel.3ThinkingHumanly:theCognitiveModellingApproach

Ifwearegoingtosaythatagivenprogramthinkslikeahuman,wemusthavesomewayofdetermininghowhumansthink.Weneedtogetinsidetheactualworkingsofhumanminds.Therearetwowaystodothis:throughintrospection—tryingtocatchourownthoughtsastheygoby—orthroughpsychologicalexperiments.Oncewehaveasufficientlyprecisetheoryofthemind,itbecomespossibletoexpressthetheoryasacomputerprogram.Iftheprogram’sinput/outputandtimingbehaviormatcheshumanbehavior,thatisevidencethatsomeoftheprogram’smechanismsmayalsobeoperatinginhumans.Forexample,NewellandSimon,whodevelopedGPS,the“GeneralProblemSolver”(NewellandSimon,1961),werenotcontenttohavetheirprogramcorrectlysolveproblems.Theyweremoreconcernedwithcomparingthetraceofitsreasoningstepstotracesofhumansubjectssolvingthesameproblems.Thisisincontrasttootherresearchersofthesametime(suchasWang(1960)),whowereconcernedwithgettingtherightanswersregardlessofhowhumansmightdoit.TheinterdisciplinaryfieldofcognitivesciencebringstogethercomputermodelsfromAIandexperimentaltechniquesfrompsychologytotrytoconstructpreciseandtestabletheoriesoftheworkingsofthehumanmind.[4]4Thinkingrationally:Thelawsofthoughtapproach

TheGreekphilosopherAristotlewasoneofthefirsttoattempttocodify“rightthinking,”thatis,irrefutablereasoningprocesses.Hisfamoussyllogismsprovidedpatternsforargumentstructuresthatalwaysgavecorrectconclusionsgivencorrectpremises.Forexample,“Socratesisaman;allmenaremortal;thereforeSocratesismortal.”Theselawsofthoughtweresupposedtogoverntheoperationofthemind,andinitiatedthefieldoflogic.

Thedevelopmentofformallogicinthelatenineteenthandearlytwentiethcenturies,providedaprecisenotationforstatementsaboutallkindsofthingsintheworldandtherelationsbetweenthem.(Contrastthiswithordinaryarithmeticnotation,whichprovidesmainlyforequalityandinequalitystatementsaboutnumbers.)By1965,programsexistedthatcould,givenenoughtimeandmemory,takeadescriptionofaprobleminlogicalnotationandfindthesolutiontotheproblem,ifoneexists.(Ifthereisnosolution,theprogrammightneverstoplookingforit.)Theso-calledlogicisttraditionwithinartificialintelligencehopestobuildonsuchprogramstocreateintelligentsystems.

Therearetwomainobstaclestothisapproach.First,itisnoteasytotakeinformalknowledgeandstateitintheformaltermsrequiredbylogicalnotation,particularlywhentheknowledgeislessthan100%certain.Second,thereisabigdifferencebetweenbeingabletosolveaproblem“inprinciple”anddoingsoinpractice.Evenproblemswithjustafewdozenfactscanexhaustthecomputationalresourcesofanycomputerunlessithassomeguidanceastowhichreasoningstepstotryfirst.[5]Althoughbothoftheseobstaclesapplytoanyattempttobuildcomputationalreasoningsystems,theyappearedfirstinthelogicisttraditionbecausethepoweroftherepresentationandreasoningsystemsarewell-definedandfairlywellunderstood.5ActingRationally:theRationalAgentApproach

Actingrationallymeansactingsoastoachieveone’sgoals,givenone’sbeliefs.Anagentisjustsomethingthatperceivesandacts.(Thismaybeanunusualuseoftheword,butyouwillgetusedtoit.)Inthisapproach,AIisviewedasthestudyandconstructionofrationalagents.

Inthe“lawsofthought”approachtoAI,thewholeemphasiswasoncorrectinferences.Makingcorrectinferencesissometimespartofbeingarationalagent,becauseonewaytoactrationallyistoreasonlogicallytotheconclusionthatagivenactionwillachieveone’sgoals,andthentoactonthatconclusion.Ontheotherhand,correctinferenceisnotallofrationality,becausethereareoftensituationswherethereisnoprovablycorrectthingtodo,yetsomethingmuststillbedone.Therearealsowaysofactingrationallythatcannotbereasonablysaidtoinvolveinference.Forexample,pullingone’shandoffofahotstoveisareflexactionthatismoresuccessfulthanasloweractiontakenaftercarefuldeliberation.

Allthe“cognitiveskills”neededfortheTuringTestaretheretoallowrationalactions.Thus,weneedtheabilitytorepresentknowledgeandreasonwithitbecausethisenablesustoreachgooddecisionsinawidevarietyofsituations.Weneedtobeabletogeneratecomprehensiblesentencesinnaturallanguagebecausesayingthosesentenceshelpsusgetbyinacomplexsociety.Weneedlearningnotjustforerudition,butbecausehavingabetterideaofhowtheworldworksenablesustogeneratemoreeffectivestrategiesfordealingwithit.Weneedvisualperceptionnotjustbecauseseeingisfun,butinordertogetabetterideaofwhatanactionmightachieve—forexample,beingabletoseeatastymorselhelpsonetomovetowardit.

ThestudyofAIasrationalagentdesignthereforehastwoadvantages.First,itismoregeneralthanthe“lawsofthought”approach,becausecorrectinferenceisonlyausefulmechanismforachievingrationality,andnotanecessaryone.Second,itismoreamenabletoscientificdevelopmentthanapproachesbasedonhumanbehaviororhumanthought,becausethestandardofrationalityisclearlydefinedandcompletelygeneral.Humanbehavior,ontheotherhand,iswell-adaptedforonespecificenvironmentandistheproduct,inpart,ofacomplicatedandlargelyunknownevolutionaryprocessthatstillmaybefarfromachievingperfection.6TheStateoftheArt

InternationalgrandmasterArnoldDenkerstudiesthepiecesontheboardinfrontofhim.Herealizesthereisnohope;hemustresignthegame.Hisopponent,Hitech,becomesthefirstcomputerprogramtodefeatagrandmasterinagameofchess.

“IwanttogofromBostontoSanFrancisco,”thetravellersaysintothemicrophone.“Whatdatewillyoubetravellingon?”isthereply.ThetravellerexplainsshewantstogoOctober20th,nonstop,onthecheapestavailablefare,returningonSunday.AspeechunderstandingprogramnamedPegasushandlesthewholetransaction,whichresultsinaconfirmedreservationthatsavesthetraveller$894overtheregularcoachfare.Eventhoughthespeechrecognizergetsoneoutoftenwordswrong,itisabletorecoverfromtheseerrorsbecauseofitsunderstandingofhowdialogsareputtogether.

AnanalystintheMissionOperationsroomoftheJetPropulsionLaboratorysuddenlystartspayingattention.Aredmessagehasflashedontothescreenindicatingan“anomaly”withtheVoyagerspacecraft,whichissomewhereinthevicinityofNeptune.Fortunately,theanalystisabletocorrecttheproblemfromtheground.OperationspersonnelbelievetheproblemmighthavebeenoverlookedhaditnotbeenforMarvel,areal-timeexpertsystemthatmonitorsthemassivestreamofdatatransmittedbythespacecraft,handlingroutinetasksandalertingtheanalyststomoreseriousproblems.

CruisingthehighwayoutsideofPittsburghatacomfortable55mph,themaninthedriver’sseatseemsrelaxed.Heshouldbe—forthepast90miles,hehasnothadtotouchthesteeringwheel.Therealdriverisaroboticsystemthatgathersinputfromvideocameras,sonar,andlaserrangefindersattachedtothevan.Itcombinestheseinputswithexperiencelearnedfromtrainingrunsandsuccessfullycomputeshowtosteerthevehicle.

Aleadingexpertonlymph-nodepathologydescribesafiendishlydifficultcasetotheexpertsystem,andexaminesthesystem’sdiagnosis.Hescoffsatthesystem’sresponse.Onlyslightlyworried,thecreatorsofthesystemsuggestheaskthecomputerforanexplanationofthediagnosis.Themachinepointsoutthemajorfactorsinfluencingitsdecision,andexplainsthesubtleinteractionofseveralofthesymptomsinthiscase.Theexpertadmitshiserror,eventually.

Fromacameraperchedonastreetlightabovethecrossroads,thetrafficmonitorwatchesthescene.Ifanyhumanswereawaketoreadthemainscreen,theywouldsee“Citroen2CVturningfromPlacedelaConcordeintoChampsElysees,”“LargetruckofunknownmakestoppedonPlacedelaConcorde,”andsoonintothenight.Andoccasionally,“MajorincidentonPlacedelaConcorde,speedingvancollidedwithmotorcyclist,”andanautomaticcalltotheemergencyservices.

Thesearejustafewexamplesofartificialintelligencesystemsthatexisttoday.Notmagicorsciencefiction—butratherscience,engineering,andmathematics.1. Homosapiensn.智人(现代人的学名)

2. antigrarityn.反重力,反引力。

3. endeavorn.努力,尽力vi.尽力,努力。

4. dimensionn.尺寸,尺度,维(数),度(数),元。

5. rationalityn.合理性,唯理性。

6. hypothesisn.假设。Vocabulary

7. aspersionn.洒水,诽谤,中伤。

8. interrogatorn.讯问者,质问者。

9. extrapolatev.推断,[数]外推。

10. cognitiveadj.认知的,认识的,有感知的。

11. syllogismn.[逻]三段论法,推论法,演绎。

12. mortaln.凡人,人类adj.必死的,致命的,人类的,临终的。

13. agentn.代理。

14. inferencen.推论。

15. stateoftheartn.技术发展水平。16. Neptunen.[天]天王星。

17. lymphn.淋巴腺，淋巴。

18. pathologyn.病理学。

19. fiendishlyadv.恶魔似地,极坏地。

20. eruditionn.博学。

[1]Althoughnoonecanpredictthefutureindetail,itisclearthatcomputerswithhuman-levelintelligence(orbetter)wouldhaveahugeimpactonoureverydaylivesandonthefuturecourseofcivilization.

虽然没有人可以详细地预测未来，但是很显然，具有人类智力水平(或更高水平)的电脑将会对我们的日常生活以及未来的文明进程产生巨大的影响。主句中it为形式主语，真正的主语是that引导的定语从句。ImportantSentences

[2]Often,scientistsinotherfieldsmovegraduallyintoartificialintelligence,wheretheyfindthetoolsandvocabularytosystematizeandautomatetheintellectualtasksonwhichtheyhavebeenworkingalltheirlives.

通常，其他领域的科学家逐步进入到了人工智能领域，他们在那里发现了能够将他们一直所从事的工作系统化和自动化的工具和词汇。where引导定语从句，修饰“artificialintelligence”。

[3]Turing’stestdeliberatelyavoideddirectphysicalinteractionbetweentheinterrogatorandthecomputer,becausephysicalsimulationofapersonisunnecessaryforintelligence.

图灵测试刻意回避询问者和计算机之间直接的物理交互，因为人的物理模拟对智能来说是不必要的。

[4]TheinterdisciplinaryfieldofcognitivesciencebringstogethercomputermodelsfromAIandexperimentaltechniquesfrompsychologytotrytoconstructpreciseandtestabletheoriesoftheworkingsofthehumanmind.

认知科学这个跨学科领域汇集了人工智能学的计算机模型以及心理学的实验技巧，试图构建人类头脑运转的准确的、可检验的理论。本句为一简单句，结构为Theinterdisciplinaryfield…brings…to….。

[5]Evenproblemswithjustafewdozenfactscanexhaustthecomputationalresourcesofanycomputerunlessithassomeguidanceastowhichreasoningstepstotryfirst.

除非有应该首先执行哪个推理步骤的提示，否则即使只有几十个论据的问题也能耗尽任何一台计算机的计算资源。

(1) OnereasontostudyAIistolearnmoreaboutourselves,itisbecausethat().

A. AIattemptstounderstandintelligententities

B. AIattemptstobuildintelligententities

C. AIisanintelligententities

D. weareintelligententities

Multiple-choiceQuestions

(2) Inthethirdparagraph,“AI,ontheotherhand,stillhasopeningsforafull-timeEinstein.”,whatisthemeaning?()

A. InAI,there’remanynewideasforonetocontributeandmoreeasilytostudy.

B. AIisnotoneofthenewestdisciplines.

C. AllthegoodideashavealreadybeentakenbyGalileo,Newton,Einstein,andtherest.

D. AIwasinitiatedformanyyears.

(3) WhichistheTuringTest?

A. Thecomputerandahumanshouldinterrogateeachother,andthec