Natural Language Processing vs. Logic.

NaturalLanguageProcessingvs.Logic.Islogicusefulinthecomputa8onal

interpreta8onoflanguage?

[email protected]

Communica8onthroughlanguage

MFOI–VadulluiVodă,29July2016


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LogicandNL

•  Logic:theexpressionofrigour•  ChallengeoflogicalformalismsinNL:codeanylanguageexpressioninlogicalform

•  Usefulness:clearoutambigui8es

•  Skep8cs:towhatextendcanamessagebeencodedinlogic?


Thelogicoflanguagecommunica8on…twohorses…–  theemiUerisaman,livesinEnglandin1926,aworkerofthefield–  thereceiveristhisman’smaster

è–  bothemiUerandreceiverhaveacommonknowledgeonthewordhorse–  theemiUerknowsthatthereceiverhasthesamemeaningashimselfonhorse–  theemiUerintendstomakethereceiverbuildtherepresenta8on:

S={x⏐horse(x)}^card(S)=2,where:card(S):thecardinalofthesetS,horse(x):aqualifyingfunc8onasser8ngthatxbelongstoaclassofobjects

sharingtheseman8cpropertythatiscurrentlydenominatedinEnglishbythewordhorse,andthatthepragma8ccontextinwhichtheexpressionisuUered

clearlyseparatesthedifferentmeaningsthatthisEnglishwordmayencode.MFOI–VadulluiVodă,29July2016

Whenislogicofhelp…


Chunkslevel:Genera8veLexiconandQualiaStructures

•  meaningofwordsdecomposedon4coordinates:– Formal(F):encodingtaxonomicinforma8onaboutthelexicalitem(theis-arela8on);

– Cons4tu4ve(C):encodinginforma8ononthepartsandcons8tu8onofanobject(part-oformade-ofrela8on);

– Telic(T):encodinginforma8ononpurposeandfunc8on(theused-fororfunc4ons-asrela8on);

– Agen4ve(A):encodinginforma8onabouttheoriginoftheobject(thecreated-byrela8on)


J.Pustejovsky.TheGenera4veLexicon.Cambridge,MA:MITPress,1995.

QualiaStructures

•  Representmeaningofcomposi8onsofwords–  largecar(F=vehicle),– brokencar(C=motor),– speedycar(T=drive),–  Italiancar(A=madeinItaly)


Whatskep8csgrump?

•  Howtomastertheenormousrangeofpossiblecombina8ons?

•  Haslikesthesamemeaning?– Helikesmysister.vs.Helikesvanillaicecream.


Discourselevel:meaningofsequencesofsentencesMariadroppedtheeggfromherhand.Shecleanedthefloor.


Tolinksentenceswemakeinferences

Mariadroppedtheeggfromherhand.



Shecleanedthefloor.Mariadroppedtheeggfromherhand.



Mariadroppedtheeggfromherhand.drops(AG:Maria,OB:egg)=>falls(REC:egg)=>touches(AG:egg,OB:X)

Qualia.Formal(egg)=container;Qualia.Cons8tu8ve(egg)={eggshell(fragile),liquid}

=>breaks(REC:eggshell)=>leaks(REC:liquid,ON:X)=>perceives(AG:Maria,OB:dirty(X))

Shecleanedthefloor.=>cleans(AG:Maria,OB:floor)=>perceives(AG:Maria,OB:dirty(floor))



ShecleanedthefloorMariadroppedtheeggfromherhand.



Mariadroppedtheeggfromherhand.Sheturnedthelighton.


Discourselevel:variabilityinlanguage

Meaning

Language Ambiguity

Variability


Discourselevel:variabilityinlanguage

•  Reducethedistancebetweenformandmeaningare:Informa8onRetrieval(IE),TextualEntailment(TE)andQues8onAnswering(QA)


TextualEntailment

•  Texttentailshypothesish(t⇒h)ifhumansreadingtwillinferthathismostlikelytrue

Atrueentailment•  t:…ashootoutattheGuadalajaraairportinMay,1993,thatkilledCardinalJuanJesusPosadasOcampoandsixothers.

•  h:CardinalJuanJesusPosadasOcampodiedin1993.


TextualEntailment

…andofafalseone•  t:ReganaTendedaceremonyinWashingtontocommemoratethelandingsinNormandy.

•  h:WashingtonislocatedinNormandy.


Howisentailmentchecked?

•  t:PhilanthropicGoldingInc.cameintoexistenceinJanuary2004.Oneyeara[eritsfounda4onthecompanydeclaredbankruptcy.

•  h:PhilanthropicGoldingInc.bankruptedinJanuary2005.



•  Launchapipelineofprocesses,attheendofwhichthesentencesofbothtandhareexpressedinasymbolicformthatallowsclosecomparison.



PhilanthropicGoldingInc.cameintoexistenceinJanuary2004.

•  Step1:tokenisa8on(notshown),part-of-speechtagging(notshown),chunkingnounphrasesandclashingmul8-wordexpressions.<NPid=”n1”>PhilanthropicGoldingInc.</NP><MWEid=”m1”>cameintoexistence</MWE>



•  Step2:recogni8onofen8tymen8ons,of8meexpressionsandresolu8onofanaphora.<COREF-LISTid=”ent1”TYPE=“ENTITY”REF-LIST=”n1”/>

PhilanthropicGoldingInc.isanameden8ty

<TIMEX38d=”t1”type=”DATE”value=”2004-01”>January2004</TIMEX3>

January2004isatemporalexpression



•  Step3:func8onaldependencyparsing;hereweshowaUniversalDependency(UD)coding



•  Step4:8meanalysis,inwhichEVENTandTLINKelements,formalizingtheeventsandtheirtemporalrela8ons,aregenerated.<EVENTeid=”ev1”VB=”m1”AG=”ent1”/>

ThecamingintoexistenceofPhilanthropicGoldingInc.isanevent

<TLINKeventID="ev1"relatedToTime="t1"relType="BEGINS"/>

ThemomentofthiseventistheonecodedbythetemporalexpressionJanuary2004


Howisentailmentchecked?•  Step5:equivalentstructures(transforma8ons)andcomputa8onoftransi8veclosuresoftemporalrela8ons:equivalenceoftheexpressions:XcomesintoexistenceandUNKNOWNfoundsXè<EVENTeid=”ev2”VB=”found”AG=”UNKNOWN”OB=”ent1”/>

ThecamingintoexistenceofPhilanthropicGoldingInc.canequallybeexpressedbyafoundingeventinwhichPGIhastheobjectrole.

<TLINKeventID="ev2"relatedToTime="t1"relType="BEGINS"/>ThemomentofthiseventistheonecodedbythetemporalexpressionJanuary

2004



Oneyeara[eritsfounda4onthecompanydeclaredbankruptcy.

•  Step1:NP-chunking<NPid=”n3”><NPid=”n2”>its</NP>founda4on</NP><NPid=”n4”>thecompany</NP><NPid=”n5”>bankruptcy</NP>



•  Step2:NER,TimexandAR<TIMEX38d=”t2”type=”DURATION”value=”P1Y”>oneyear</TIMEX3>

oneyearisatemporalexpression<COREF-LISTid=”ent1”TYPE=”ENTITY”REF-LIST=”n1n2n4”/>

itsandthecompanyarecoreferen8alwithPhilanthropicGoldingInc.

<COREF-LISTid=”eve1”TYPE=”EVENT”REF-LIST=”ev1ev2n3”/>itsfounda4onisrecognisedasaneventcoreferen8alwiththefoundingof

PhilanthropicGoldingInc.

<COREF-LISTid=”eve2”TYPE=”EVENT”REF-LIST=”n5”/>banckrupcyisrecognisedasanevent



•  Step3:UD



•  Step4:EVENTandTLINKelements<EVENTeid=”e3”POS=”VERB”CLASS=”REPORTING”AG=”ent1”OB=”eve2”>declared</EVENT><EVENTeid=”e4”POS=”NOUN”CLASS=”OCCURRENCE”AG=”ent1”>bankruptcy</EVENT>

BothactsofdeclaringbankruptcyandofbankruptcyitselfinvolvingPhilanthropicGoldingInc.arerecognisedasevents.

<TLINKeventID="e3"relatedToTime="t2"relType="AFTER"/><SLINKeventID="e3"subordinatedEvent="e4"relType="FACTIVE"/>Thedeclaringbankruptcyeventtakesplaceoneyearayerthefounda8on

event.



•  Step5:theTimeClosuretool<TIMEX38d=”t4”type=”DATE”value=”2005-01-xx”/><TLINKeventID="e4"relatedToTime="t4"relType="DURING"/>

ThedeclaringbankruptcyeventtakesinJanuary2005.


Howisentailmentchecked?PhilanthropicGoldingInc.bankruptedinJanuary2005.

•  Asimilarprocessingchainproduces:<EVENTeid=”e5”POS=”VERB”AG=”ent1”>bankrupted</EVENT>

AneventofbankruptcyinwhichisinvolvedPhilanthropicGoldingInc.

<TIMEX38d=”t5”type=”DATE”value=”2005-01-xx”>January2005</TIMEX3><TLINKeventID="e5"relatedToTime="t5"relType="DURING"/>

ThemomentofthiseventisJanuary2005.

Otherformalisms

•  NaturalLogic:TreestructuredRecursiveNeuralNetworkscanlearntoiden8fylogicalrela8onshipssuchasentailmentandcontradic8on…


Andwhenlogicisofnouse?...


Doublenega8on

•  DoubleNega?onlanguages(amongwhichstandardvarie8esofGermanicandScandinavian):–  twonega8veelementscanceleachotherout

resul8nginaposi8vereading:Pauldidn’tseenobody.=Paulsawsomebody.“Thereisanindividualx,suchthatPaulsawx.”

A.Falaus.RomanianN-wordsasNega4veQuan4fiers,WorkingPapersinLinguis8cs,31stAnnualPennLinguis8csColloquium,Univ.Pennsylvania,2008.


Doublenega8on

•  Nega?veConcordlanguages(amongwhichRomanianandItalian):– mul8pleoccurrencesofnega8onareinterpretedasoneseman8cnega8on:Pauln-avăzutpenimeni.=Pauldidn’tseeanybody.“Itisnotthecasethatthereisanindividualx,suchthatPaulsawx.”


Linearposi8onambivalence

•  Associa8onsnoun+adjec8vevs.adjec8ve+nounhavedifferentmeanings

femeiasingură=>thewomanalonesingurafemeie=>theonlywoman

A.Cornilescu.Thelineariza4onoftheRomanianadjec4vesandthestructureoftheRomanianDP,inTorckD.andWetzlesL.(eds),RomanceLanguages

andLinguis8cTheory,2006",JohnBenjamins,2009.


Linearposi8onambivalence

today10yearsago

mașinalui(cea)vechevechealuimașină


Linearposi8onambivalence…

•  …doesnotapplytoanyadjec8ve:certainmodifiersmakesenseonlywhensituatedinthepre-posi8onwithrespecttothemodifiednounbiet(poor,pi4ful)isnotacceptedunlessitprecedesthenoun:bietom(poorman),butnot:ombiet M.-D.Vulchanova.Modifica4onintheBalkannominalexpression:Anaccountof

the(A)NA–AN(A)ordercontract.InMar8neCoeneandYvesD’hulst(eds):FromNPtoDP:Thesyntaxandseman8csofnounphrases,JohnBenjamin,2003.


Linearposi8on

•  Theintersec8on-basedcomposi8oncontradicted:–  ifX(adj)andY(noun),thenXY(orYX):•  setofobjectsYthathavethepropertyX•  intersec8onbetweenthesetofobjectshavingthepropertyXandthesetofobjectsY

è poormen:intersec8onbetweenthesetofthingswhicharepoorandthesetofmen

è s8ll,bieţiioameni:subsetofthesetofmenwhichareinapi8ful/miserablestate


Contextsandthemistofpragma8cs

•  Textualcontext:sensefixedbythecontext•  Disambigua8oncomputedsta8s8cally…

GoogleTranslate


Textualcontextandwordsenses

•  LogiclackspowerHowwouldalogicalsolu8onwork?Andifoneexists,whatwouldbethecostofthesuppor8velexical-seman8cresourcestogeneraliseit?


Thewoodlanguage•  Wordsinducedifferentreac8onsinhumans:

herehumorous(contrarytotheinten8on)“SăluptămpentrupropăţireaneamuluişiaducereaRomânieipecelemaiînalteculmidecivilizaţiemul8lateraldezvoltată.”(approx.Let’sfighttothriveours4rpsandbringRomaniaonthehighestpeaksofmul4laterallydevelopedciviliza4on.)R.Zafiu.Limbadelemn(Thewoodlanguage).InDilemaveche,Nr.314/

18-24februarie,2010.

Thewoodlanguage

“Pusas�elînlumină,ancoratînsinergiafaptelor,recursullauniversalitatenueludeazămeandreleconcretului.”(approx.Thusputinlight,anchoredinthesynergyoffacts,theappealtouniversalitydoesnotcircumventthemeandersoftheconcrete.)

aUributedtoIonIliescu


Styleinliterature

•  Humansperceiveco-occurrenceofwordsasproducingverysugges8veimages“constelațiaochilormei”(theconstella4onofmyeyes)“a8ngicuauzul”(approx.yourhearingtouches)“nisipuridefiară”(beastsands)NichitaStănescu,Autoportretîn4mpdeveghe(Autoportraitduringwatch

8me)


Styleinliterature

•  Seizingemo8onsincurredbysentenceslikethefollowinginlogicalexpressions?"It’senoughformetobesurethatyouandIexistatthismoment.”

GabrielGarciaMarquez:OneHundredYearsofSolitude


Styleinliterature

•  Formaliseinlogicaltermsametonymicsenseofanexpression?“lipindu-sederăcoareatoculuiuşii”(approx.s4ckingtothechillofthedoorframe)

GabrielGarciaMarquez:OneHundredYearsofSolitude

Atouchedobjectisreplacedwithasensa8onthattheagentborrowsfromthatobject.


Styleinliterature

•  Lookforlogicalequivalentofmetaphoricallanguage:“Temângâicudegetelemuiateînamin8ri.”(Icaressyouwithmyfingersdippedinmemories)


Styleinliterature

•  Confrontedwiththeextraordinarydiversityofsugges8onsthatwordscanconvey,logicseemstomefaint,forceless,impuissant.

•  Howcouldsuchpoe8calexpressionsbeencodedinlogicalconstruc8ons?


Andthesolu8onis?

•  Logicprovessuccessfulinrepresen8ngmanylanguageaspects.

•  Thereshouldbealimitwheretheambi8ontoexpressnaturallanguageinlogicalformhastostopbecauseitreachesaninsurmountablelimit.


Andthesolu8onis?•  4categoriesofthinkersontherela8onshipbetweenlanguageandlogic–  thelogicpurists:everythingcanbeexpressedinlogical(symbolic)forms

–  thesta8s8cal-neuralpurists:everythingcanbeexpressedbysta8s8cs/neuralformalisms

–  theskep8cals:languagecanneverbeinterpretedtotally,neitherbysymbolicnorsta8s8calmeans

–  themoderates,dirtyworkers:onlyacombina8onbetweenthetwoparadigmscanhelp,andthisonlytoacertainlimit


Insteadofconclusions

•  Theirlackofconfidenceinlogicasauniversalmachineryforprocessinglanguagecomesfromobserva8onsoftheinabilityoflogictosupportexhaus8velytheprocessinginfrastructuresoflanguage.

•  Theydon’tbelievethateachsentence,oreachsequenceofsentences,shouldbetransformedintoatheoremthatnecessitatesaproof.


Insteadofconclusions

•  Reasoning,thatpartoflanguageusethatnecessitatesvoli8onalconnec8onsinordertodecipherinforma8on,tofindexplicitlinks,withoutwhichunderstandingwouldbeimpossible–yes.

•  Primaryprocessesthatenabletheuseoflanguagetoexpressemo8ons,thereforethatallowcogni8onbasedonlanguage–no.


Thankyou!


Natural Language Processing vs. Logic.

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