IntroductiontoAI7th Lecture

1980’s– BodyoverMind

WouterBeekme@wouterbeek.com4 November2010

PartI

1980’s,BodyoverMind

NouvelleAI0 Sensorimotorskillsareessentialtohigherlevelskillslikecommonsensereasoning.

0 Abstractreasoningistheleastinterestingorimportanthumanskill.

0 Sowhocameupwiththeidea…(thoughtentatively)?0 “It[…]isbesttoprovidethemachinewiththebestsenseorgansthatmoneycanbuy[…].Thatprocesscouldfollowthenormalteachingofachild.”

0 AlanTuring,1950

EmbodiedAI– philosophicalposition0 Embodiment:Thefunctionsofthemindcanbedescribedintermsofaspectsofthebody.0 Cognitivism:thefunctionsofthemindcanbedescribedintermsofinformationprocessing.

0 Computationalism:thefunctionsofthemindcanbedescribedincomputationalterms.

0 Cartesiandualism:thefunctionsofthemindaredescribedinimmaterialterms.

0 Embodimenthypothesis:conceptualandlinguisticstructuresareshapedbythepeculiaritiesofperceptualstructures.[Lakoff& Johnson1999]

Remember:Moravecparadox0 Optimismduetomachinessolvingthingsthataredifficultforhumans:0 Geometricalproblems0 Logicalproofs0 Gamesofchess

0 Butthingsthatareeasyforhumansareoftendifficultformachines:0 Takingthegarbageout.0 RecognizingthemanwalkingacrossthestreetisJoe.

0 Sensorimotorskillsandinstinctsare(arguably)necessaryforintelligentbehavior,butposeenormousproblemsformachines.

Moravecparadox– Theargument0 Thetimethatevolutiontooktoproduceacertainskillisproportionaltothedifficultytoimplementthatskill.

0 Theoldesthumanskillsareunconsciousandeffortless.0 Theyoungesthumanskillsareconsciousandrequirelotsofeffort.

0 Effortlessskillsarethemostdifficulttoimplement.0 Difficultskillsaretheeasiesttoimplement,oncetheeffortlessskillshavebeenimplemented.

But:0 Culturalevolutionisfasterthanbiologicalevolution.0 Temporalprogressionneednotparallelcomplexity.0 Temporalprogressionsuggestsaquantitativedevelopment.

Bottom‐upapproachBottom‐upapproach:Followtheevolutionarytrail,increasingthecomplexityofartificialagents.

Contrastthisto:0 Top‐downapproach:startoffwithconsciousreasoningandaddsensors/actuatorslater.

0 Only‐topapproach:onlysolveconsciousreasoningproblems,planning,conceptuallearningandlanguage.Sensors/actuators,althoughinteresting,arenotapartofAI.

SubsumptionarchitectureCharacteristics:0 Taskdecomposition0 Parallelprocessing:layershavingindependentgoals.0 Bottom‐updesign:fromunconscioustoconsciousbehavior.

0 Nointernalrepresentation:layershavingimplicitgoals

Advantages:0 Modularity0 Robustness,autonomy0 Iterativedevelopmentandtesting

Reactiveplanning0 Operateinatimelyfashion

0 Workindynamicandunpredictableenvironments.0 Computeonlythenextaction,basedonthecurrentstimuli.

0 Cognitiveminimalism:behaviormodulesareFSM’swithoutmemoryorlearningabilities.

Neats&scruffies0WhatisthebestwaytoconductAIresearch?0 Neats:Byproducingelegantsolutionswithinatheoreticalframework.0 Includingaformalnotionofoperation,e.g.provability.

0 Scruffies:Byhackingandtweaking.0 Mid‐1970’s:RogerSchank definesthedistinction.0 1983:NilsNilsson,bothareneeded@AAAIpresidentialaddress.

0 1989:RodneyBrooks,robotsshouldbefast,cheapandoutofcontrol.

0 2000’s:Thevictoryoftheneats?Russell&Norvig,p25.

PartIIReasoningwithoutRepresentation

Evolutionarydecomposition0 Inevolutionaryterms,reactingandactingtooklongertodevelopthanintelligenceandexpertknowledge.

0 Critique:Thetemporalprogressionofintelligentlifeformsneednotbeinlinewiththequalitativenorwiththequantitativeprogressionofintelligentfunctions.

0 ArtificialFlightresearchersthattrytoemulateamodernairplanebysubdividingtasksbasedoncomponentsegmentationwillnotmanagetogettothegistoftheproblem,i.e.aerodynamics.

0 Ingeneral:decompositionshouldproceedevolutionary,fromsimpletocomplex(orbottom‐up)andnotbysegmentingthecomplex(top‐down).

Brooks:AIasanempiricalscience0 AIshouldposeandverifyhypotheses(rememberNewell&Simon).

0 ButAIneverfails,sosomethingmustbewrong.0 AIalwayssucceedsbydefiningtheunsolvedpartsofaproblemasnotpertainingtoAI.

0 Thisisdonebyfactoringoutallaspectsofperceptionandaction.

0 Thisisadubiousformofabstraction(anditexplainstheBrittlenessproblem).

0 Critique:AIoftenfails,andthisfailureisnotalwaysrelatedtoperceptionoraction.0 ForinstanceMachineTranslationresearchofthe1950'sand1960'shasfailedbecauseoftheopenworldproblem.

Brittlenessproblem0 Brittlenessproblem:Theinabilitytocopewithunexpectedchangesintheenvironment.

0 ThebrittlenessprobleminAIiscausedbythedivisionbetweenperception,actionandreasoning.Inrealorganismsthereisnosuchsegmentation.

0 ThesolutionisaspecificinterpretationoftheempiricalenterpriseofAIresearch:0 Nottop‐downhypothesisvalidation,butbottom‐upengineering.

AIasbottom‐upengineering0 AIshouldbetheengineeringtaskofbuildingCreatures that0 arecompletelyautonomousmobileagents0 co‐existwithhumansintheworld0 areseenbyhumansasintelligentbeingsintheirownright

0 Creaturesshouldfollowthefollowingengineeringprinciples.Theyshould0 operateinatimelyfashion0 berobust,exhibitingagradualchangeincapabilityunderenvironmentalchange

0 maintainmultiplegoals0 dosomething,haveapurposeinbeing

Horizontalvs verticallayers0 [A]IntraditionalAIresearch,theassumptionsthatindependentresearchfieldsmakearenotforcedtoberealistic.Thisisabuginthefunctionaldecompositionapproach.0 Theverticallayers:machinelearning,vision,knowledgesystems,automatictranslation.

0 [B]Thetraditionaldecompositionseparates,amongotherthings,peripheralperceptionandactionmodulesfromcentralreasoningorprocessingmodules.

0 Thefactthat[A]assumptionsarenotenforced,doesnotimply[B]thattheunderlyingdecompositioniswrong.0 Itmustbeshownthatunderthetraditional,functionaldecompositionoftheresearchfield,assumptionscannotpossiblybeenforced.

0 Whatreallyplaysarolehere:theassumptionthatreasoningandlanguageareheavilyinfluencedbysensorsandactuators,andbybeingintheworld.0 Thehorizontallayers:obstacleavoidance,pathfinding,pathplanning.

Sparsenessofrepresentations0 Theworldisitsownbestrepresentation.0 Noworldmodelmaintenance,somorerobust.0 Eachlayerhasanindependentandimplicitpurposeorgoal.

0 ThepurposeoftheentireCreatureisimplicitinthecollationoftheindependentpurposesoftheindividuallayers.

Layerinteractionsinnon‐symbolicterms:0 Suppression:side‐tapping,replacinganoriginalinputmessagebyamessagefromalowerlevel.

0 Inhibition:side‐tapping,inhibitinganoutputmessagewithoutreplacingit.

Activity‐ProducingSubsystemDecomposition

Combines:0 [1]bottom‐updecomposition(activity‐producing)0 [2]horizontallayering(subsystem)Brooksaddstothis[3]thesparsenessofrepresentations.

EmbodiedAI’sDisadvantages

0 Meta‐cognition:noreificationoftasks,goals orprocesses.

0 Goalinterference:independentgoal‐directedbehaviors.

0 Taskcoordination:subsumptioninthecaseofmultiplelevelsisweaklystructured.

0 Learning:relatedtothemeta‐cognitiondisadvantage,sincethereisnomediuminwhichlearningcantakeplace,i.e.noreificationofthoughts.