Controlling logical scope in text generation
Controlling logical scope in text generation
Controlling logical scope in text generation
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<strong>Controll<strong>in</strong>g</strong><strong>logical</strong><strong>scope</strong><strong>in</strong><strong>text</strong><strong>generation</strong><br />
RichardPower<br />
ITRI,UniversityofBrighton<br />
LewesRoad,BrightonBN24AT,UK<br />
Richard.Power@itri.bton.ac.uk<br />
Abstract<br />
ManyapplicationsofNaturalLanguageGen-<br />
erationemployobject-orientedknowledge<br />
representationformalismssuchasloom.<br />
Eachentity<strong>in</strong>thedoma<strong>in</strong>isrepresentedby<br />
anobjectbelong<strong>in</strong>gtoaspeciedclassand<br />
possess<strong>in</strong>gattributessuitableforthatclass.<br />
Froma<strong>logical</strong>viewpo<strong>in</strong>t,doma<strong>in</strong>entitiescor-<br />
respondtoexistentiallyquantiedvariables,<br />
buts<strong>in</strong>celoomandk<strong>in</strong>dredformalismspro-<br />
videnoscop<strong>in</strong>gmechanisms,ithastobeas-<br />
sumedthatallvariableshavewide<strong>scope</strong>.For<br />
technicalmaterial<strong>in</strong>clud<strong>in</strong>gconditional,neg-<br />
ativeormodalcon<strong>text</strong>sthisisaseriouslimi-<br />
tation.Wesuggestasimpleextensiontostan-<br />
dardobject-orientedformalismswhichallows<br />
encod<strong>in</strong>gof<strong>logical</strong><strong>scope</strong>,andshowhowlog-<br />
icallycomplexmaterialcanbeeditedus<strong>in</strong>g<br />
the`wysiwym'approach.<br />
1 Introduction<br />
ManyNaturalLanguageGeneration(nlg)<br />
applications(Parisetal.,1995;Bateman,<br />
1996)encodethecontentofthegenerated<br />
<strong>text</strong>s<strong>in</strong>anobject-orientedknowledgerepre-<br />
sentationformalism,suchasloom(MacGre-<br />
gorandBates,1987).Inloomandk<strong>in</strong>dred<br />
languages,adist<strong>in</strong>ctionismadebetweenthe<br />
`T-box',whichdenestheclassestowhichob-<br />
jectsmaybelong,andthe`A-box',whichde-<br />
ThisworkissupportedbytheEng<strong>in</strong>eer<strong>in</strong>gand<br />
PhysicalSciencesResearchCouncil(epsrc)Grant<br />
L77102.<br />
conta<strong>in</strong> cream<br />
patient<br />
SUBJECT OWNER<br />
OBJECT<br />
agent<br />
antiviral<br />
aciclovir<br />
NAME<br />
Figure1:A-boxforsimpleassertion<br />
scribesthepropertiesofspecicentitiesbe-<br />
long<strong>in</strong>gtotheseclasses.TheT-boxserves<br />
asanontologythatdeterm<strong>in</strong>esthesemantic<br />
coverageofthesystem;theA-boxrepresents<br />
thecontentofagenerated<strong>text</strong>,orperhaps<br />
awiderbodyofknowledgefromwhichthis<br />
contentisdrawn.<br />
Thesemanticnetwork<strong>in</strong>gure1showsa<br />
simpleA-boxunderly<strong>in</strong>gthesentence1:<br />
Yourcreamconta<strong>in</strong>sanantiviral<br />
agentcalledaciclovir<br />
Eachnodeofthenetworkrepresentsanen-<br />
tity;thenodelabelrepresentstheclassofthe<br />
entity;outgo<strong>in</strong>garcsrepresentitsproperties.<br />
Inalanguagelikeloom,theA-boxwouldbe<br />
encodedthroughasetofassertions:<br />
(tell(conta<strong>in</strong>u1)<br />
(subjectu1u2)<br />
(creamu2)<br />
(owneru2u3)<br />
1Throughoutthepaper,ourexampleswillbetaken<br />
fromthedoma<strong>in</strong>ofPatientInformationLeaets,the<br />
<strong>in</strong>structionslips<strong>in</strong>sidemedic<strong>in</strong>epackets.
(patientu3)<br />
(objectu1u4)<br />
(antiviral-agentu4)<br />
(nameu4u5)<br />
(acicloviru5))<br />
Howshouldsuchasetofassertionsbe<strong>in</strong>-<br />
terpreted<strong>logical</strong>ly?Theusualassumptionis<br />
thatthe`entities'u1,u2etc.(orthenodes<br />
<strong>in</strong>gure1)shouldbetreatedasexistentially<br />
quantiedvariableswithwide<strong>scope</strong>.Under<br />
thisassumption,thecontentoftheA-box<br />
couldberepresentedbyas<strong>in</strong>glepredicatecal-<br />
culusformula:<br />
[9u19u29u39u49u5conta<strong>in</strong>(u1)<br />
&subject(u1;u2)&cream(u2)<br />
&owner(u2;u3)&patient(u3)<br />
&object(u1;u4)&antiviral(u4)<br />
&name(u4;u5)&aciclovir(u5)]<br />
Sofarsogood,butwhathappenswhenan<br />
assertionconta<strong>in</strong>sanvariablewithnarrow<br />
<strong>scope</strong>?Thishappensoften<strong>in</strong><strong>in</strong>structional<br />
doma<strong>in</strong>ssuchaspatient<strong>in</strong>formationleaets,<br />
<strong>in</strong>whichconditional,negativeandmodalcon-<br />
<strong>text</strong>sabound.Considerforexamplethe<strong>in</strong>-<br />
struction<br />
Ifyoudeveloparash,youshould<br />
consultyourdoctor.<br />
forwhichaplausible<strong>logical</strong>formis<br />
[9p9ddoctor(p;d)&<br />
[[9rrash(r)&develop(p;r)]!<br />
2consult(p;d)]]<br />
Therashrcannotbeassignedwide<strong>scope</strong>here<br />
withoutimply<strong>in</strong>gthatitisa`real'entity,like<br />
thepatientandthedoctor,ratherthanahy-<br />
potheticalentityboundtotheantecedentof<br />
theconditional.<br />
Attemptshavebeenmadetogeneratesuch<br />
sentencesfromaloomknowledgebase.The<br />
penmanGeneralizedUpperModel(Bate-<br />
manetal.,1995)allowsabstractentities<br />
represent<strong>in</strong>g<strong>logical</strong>relations,byprovid<strong>in</strong>g<br />
classesequivalenttothe<strong>logical</strong>operatorsof<br />
implicationandobligation(theconcept<br />
CONSEQUENT<br />
ANTECEDENT<br />
develop consult<br />
ACTOR ACTEE<br />
ACTOR<br />
ACTEE<br />
CONTENT<br />
u0<br />
u1<br />
u2<br />
u3<br />
implication obligation<br />
OWNER<br />
u4<br />
rash<br />
u5<br />
patient<br />
u6<br />
doctor<br />
Figure2:A-boxforconditional<strong>in</strong>struction<br />
namesactuallyused<strong>in</strong>theUpperModelare<br />
<strong>logical</strong>-conditionandnecessity).AnA-<br />
boxthatapproximatelyrepresentsthemean-<br />
<strong>in</strong>goftheconditional<strong>in</strong>structioncanthere-<br />
forebedened,as<strong>in</strong>gure2.However,this<br />
A-boxfailsto<strong>in</strong>dicatethatthepatientand<br />
doctorentitieshavewide<strong>scope</strong>whilethe<br />
rashentityhasnarrow<strong>scope</strong>.<br />
Thispaperhastwoaims.First,wepropose<br />
asimplemethodbywhichanobject-oriented<br />
knowledgeformalismlikeloomcanbeaug-<br />
mented<strong>in</strong>ordertorepresent<strong>scope</strong>dist<strong>in</strong>c-<br />
tions.Secondly,weshowhowtheaugmented<br />
knowledgerepresentationcanbeeditedbythe<br />
`wysiwym'method(PowerandScott,1998;<br />
Scottetal.,1998),soallow<strong>in</strong>gauthorswho<br />
arenotlogiciansorknowledgeeng<strong>in</strong>eersto<br />
encode<strong>logical</strong>lycomplexknowledge.<br />
2 Logicalcon<strong>text</strong><br />
S<strong>in</strong>cethebeg<strong>in</strong>n<strong>in</strong>gofmodernlogic,net-<br />
workdiagramshavebeenemployedascon-<br />
venientrepresentationsof<strong>logical</strong>formwith<br />
implicitexistentialquantication.Pierce's<br />
ExistentialGraphs(Roberts,1973)were<strong>in</strong>-<br />
troduced<strong>in</strong>1897;accord<strong>in</strong>gtoSowa(1995)<br />
theyareformallyequivalenttoDiscourseRep-<br />
resentationStructures(drss)(Kamp,1981).<br />
Inbothnotations,scop<strong>in</strong>gassignmentsare<br />
madebyb<strong>in</strong>d<strong>in</strong>gentitiesandrelationshipsto<br />
<strong>logical</strong>con<strong>text</strong>s,representedby`ovalenclo-
sures'<strong>in</strong>ExistentialGraphsandby`boxes'<br />
(ordrss)<strong>in</strong>DiscourseRepresentationThe-<br />
ory(drt).Sowa'smoreelaborateConcep-<br />
tualGraphnotationrepresents<strong>logical</strong>con-<br />
<strong>text</strong>sthroughcomplex`proposition'nodes<br />
whichenclosesub-networks.Hendrix(1975)<br />
hasproposedasimilarnotation<strong>in</strong>whichthe<br />
nodesandarcsofasemanticnetworkareas-<br />
signedto`spaces',buts<strong>in</strong>ceheallowsthese<br />
spacestooverlap,hisdiagramscannotalways<br />
bedrawnunambiguouslyonaplane.<br />
Alltheserepresentationsarecapableof<br />
express<strong>in</strong>g<strong>scope</strong>dist<strong>in</strong>ctions,sothechoice<br />
amongthemisdictatedma<strong>in</strong>lybyconve-<br />
nience.Wewilladoptherethedrtframe-<br />
work,whichhasbeenemployed<strong>in</strong>muchre-<br />
centwork<strong>in</strong>l<strong>in</strong>guistics.Figure3showsa<br />
drtdiagramforthesentence`Ifyoudevelop<br />
arashyoushouldconsultyourdoctor'.For<br />
readersunfamiliarwithdrt,theconventions<br />
ofthediagramwillbeexpla<strong>in</strong>edbriey.It<br />
conta<strong>in</strong>sfourboxeslabelledK0..K3,vedis-<br />
coursereferents(u1,u3,u4,u5,u6)eachas-<br />
signedtotheuniverseofabox,tensimple<br />
conditions<strong>in</strong>predicate-argumentform,and<br />
twocomplexconditionsbasedonthe<strong>logical</strong><br />
operatorsofimplication())andnecessity<br />
(2).Intuitively,eachboxrepresentsa<strong>logical</strong><br />
con<strong>text</strong><strong>in</strong>volv<strong>in</strong>gsomeentities(discourseref-<br />
erents)thatbelongtoitsuniverse.Theouter<br />
boxK0representsthecon<strong>text</strong>armedbythe<br />
authorofthepatient<strong>in</strong>formationleaet;it<strong>in</strong>-<br />
cludesthepatientu5,thepatient'sdoctoru6,<br />
threesimpleconditionpresent<strong>in</strong>gproperties<br />
ofthesereferents,andacomplexcondition<br />
present<strong>in</strong>gtheconditional<strong>in</strong>struction.The<br />
<strong>in</strong>struction<strong>in</strong>itsturnconta<strong>in</strong>saboxK1de-<br />
scrib<strong>in</strong>gahypotheticalcon<strong>text</strong><strong>in</strong>whichthe<br />
patientdevelopsarash.Acrucialidea<strong>in</strong>drt<br />
isthatareferentmaybecitedonly<strong>in</strong><strong>logical</strong><br />
con<strong>text</strong>sthatareaccessiblefromtheboxto<br />
whichitisbound.For<strong>in</strong>stancetherashu4,<br />
whichisboundtothehypotheticalcon<strong>text</strong><br />
K1,couldoccurwith<strong>in</strong>asimplecondition<strong>in</strong><br />
anyoftheboxessubord<strong>in</strong>atedtoK1(i.e.K2<br />
andK3),butnot<strong>in</strong>theouterboxK0.Intu-<br />
itively,tociteu4with<strong>in</strong>K0wouldimplythat<br />
therashdenitelyexisted,<strong>in</strong>whichcaseu4<br />
shouldhavebeenboundtoK0,nottoK1.<br />
3 Scopedsemanticnetwork<br />
Whatisthem<strong>in</strong>imum<strong>in</strong>formationthatneed<br />
beaddedtotheA-box<strong>in</strong>gure2<strong>in</strong>order<br />
torepresentfullythe<strong>logical</strong>formofthecon-<br />
ditional<strong>in</strong>struction,asshownbythedrs<strong>in</strong><br />
gure3?Thisquestioncanbeaddressedby<br />
seek<strong>in</strong>gaprocedurefor<strong>in</strong>terpret<strong>in</strong>gaseman-<br />
ticnetworklikegure2asadrs,andnot<strong>in</strong>g<br />
exactlywherethisprocedurestalls.<br />
Therststep<strong>in</strong><strong>in</strong>terpret<strong>in</strong>ggure2asa<br />
drsistodist<strong>in</strong>guishnodesthatexpresssim-<br />
pleconditionsfromonesthatexpresscom-<br />
plexconditions.Thisisstraightforward:the<br />
T-boxclassicationshoulddist<strong>in</strong>guish<strong>logical</strong><br />
operatorslikeimplicationandobligation<br />
fromnon-<strong>logical</strong>entitieslikeactionsorphysi-<br />
calobjects,so<strong>in</strong>gure2wecanconcludethat<br />
u0andu2expresscomplexconditionswhileall<br />
othernodesexpresssimpleconditions.<br />
Thesecondstepistopairsomenodeswith<br />
drtboxes;thiscanbedonebyapply<strong>in</strong>gtwo<br />
rules.Therootofthenetworkispairedwith<br />
theouterboxK0.<br />
Ifanodeexpressesacomplexcondition,<br />
itsdirectdescendents(i.e.thevaluesof<br />
itsattributes)arepairedwithboxes.<br />
Ingure2,theserulesyieldfourboxes:K0<br />
ispairedwithu0,therootofthenetwork;K1<br />
andK2arepairedwithu1andu2,thedirect<br />
descendentsoftheimplicationu0;andK3is<br />
pairedwithu3,thedirectdescendentofthe<br />
obligationu2.<br />
Thethirdstepistoplaceeachcomplexcon-<br />
dition<strong>in</strong>thecorrectbox,soobta<strong>in</strong><strong>in</strong>gthebox<br />
structure<strong>in</strong>gure3.Aga<strong>in</strong>tworulessuce:<br />
IfanodeuAexpress<strong>in</strong>gacomplexcondi-<br />
tionispairedwithaboxKA,thecomplex<br />
conditionshouldbeplaced<strong>in</strong>KA.
K0:u5u6<br />
patient(u5)<br />
doctor(u6)<br />
owner(u6,u5)<br />
K1:u1u4<br />
develop(u1)<br />
rash(u4)<br />
actor(u1,u5)<br />
actee(u1,u4) ) K2:<br />
2K3:u3<br />
consult(u3)<br />
actor(u3,u5)<br />
actee(u3,u6)<br />
Figure3:DRSforaconditional<strong>in</strong>struction<br />
IfuAisnotpairedwithabox,wendthe<br />
nearestancestoruBthatispairedwitha<br />
boxKB,andplacethecomplexcondition<br />
expressedbyuA<strong>in</strong>KB.(Theremustbea<br />
uniquenearestancestor,s<strong>in</strong>ceanetwork<br />
isill-formediftherearetwopathslead<strong>in</strong>g<br />
fromtherootnodetoanodeexpress<strong>in</strong>g<br />
acomplexcondition.)<br />
Apply<strong>in</strong>gtheserulestogure2,wecanplace<br />
theimplicationu0<strong>in</strong>K0,andtheobligation<br />
u2<strong>in</strong>K2,theconsequentoftheimplication.<br />
Thefourthstepistob<strong>in</strong>deachreferentrep-<br />
resentedbyanode<strong>in</strong>gure2tothecorrect<br />
box.Wecanignorethenodesexpress<strong>in</strong>gcom-<br />
plexconditions(u0andu2),s<strong>in</strong>ceabstracten-<br />
titiesofthisk<strong>in</strong>dareusuallyomittedfrom<br />
drtdiagrams.Amongtheothernodes,we<br />
candist<strong>in</strong>guishnodespairedwithboxes(u1<br />
andu3)fromtherest(u4,u5andu6).The<br />
formerwillbecalledxedreferents,thelat-<br />
teroat<strong>in</strong>greferents.The<strong>scope</strong>ofaxed<br />
referentisdeterm<strong>in</strong>ed:itmustbeboundto<br />
theboxitispairedwith.Thusu1mustbe<br />
assignedtotheuniverseofK1,andu3must<br />
beassignedtotheuniverseofK3.Foroat-<br />
<strong>in</strong>greferentstheremaybeachoice.Byap-<br />
ply<strong>in</strong>gdrtaccessibilityrules,asetofpoten-<br />
tial<strong>scope</strong>scanbecalculatedforeachoat<strong>in</strong>g<br />
referent;ifthissetconta<strong>in</strong>smorethanone<br />
boxthe<strong>scope</strong>ofthenetworkisunderspeci-<br />
ed,andsothenetworkfailstodeterm<strong>in</strong>ea<br />
uniquedrs.<br />
Wenowhaveananswertoourorig<strong>in</strong>al<br />
question:to<strong>in</strong>terpretanA-boxlikegure2as<br />
adrs,eachoat<strong>in</strong>greferentmustbeassigned<br />
a<strong>scope</strong>.S<strong>in</strong>cexedreferentsarepairedwith<br />
boxes,thiscanbedonebyl<strong>in</strong>k<strong>in</strong>geachoat-<br />
<strong>in</strong>greferenttoaxedreferentthatbelongsto<br />
itssetofpotential<strong>scope</strong>s;wewillcallthere-<br />
sulta`<strong>scope</strong>dsemanticnetwork'.Ingure4,<br />
<strong>scope</strong>assignmentsareshownbydottedarcs;<br />
asanaidtovisualization,oat<strong>in</strong>greferents<br />
arerepresentedbyovalsandxedreferents<br />
(pairedwithboxes)byrectangles.<br />
Hav<strong>in</strong>gassignedeachreferenttoabox,the<br />
fthandnalstepistoplacethesimplecon-<br />
ditions<strong>in</strong>thecorrectboxes.Simplecondi-<br />
tionsareoftwok<strong>in</strong>ds,assertionsofclassmem-<br />
bershipsuchasconsult(u3)andattributions<br />
suchasactor(u3;u5),theformerexpressed<br />
bynodes<strong>in</strong>thenetworkandthelatterby<br />
arcs.Weassumethatifareferentuisbound<br />
toaboxK,thenallsimpleconditionsde-
CONSEQUENT<br />
ANTECEDENT<br />
develop<br />
OWNER<br />
consult<br />
ACTOR ACTEE<br />
ACTOR<br />
ACTEE<br />
CONTENT<br />
u0<br />
u1<br />
u2<br />
u3<br />
implication obligation<br />
u4<br />
rash doctor<br />
u6<br />
u5<br />
patient<br />
Figure4:A-boxwith<strong>scope</strong>assignments<br />
scrib<strong>in</strong>gpropertiesofu(i.e.itsclassand<br />
itsattributes)shouldbeplaced<strong>in</strong>K.Thus<br />
actor(u3;u5)isplaced<strong>in</strong>K3becauseitde-<br />
scribesapropertyofu3,whichisboundto<br />
K3.Ingeneral,anysimpleconditionofthe<br />
formr(uA;uB)isplaced<strong>in</strong>theboxtowhich<br />
uAisbound,evenifuBisboundtoadierent<br />
box.<br />
Itmightseemthatthisassumptionistoo<br />
strong.Bycomparison,Hendrix(1975)b<strong>in</strong>ds<br />
eacharcaswellaseachnodetoa<strong>logical</strong><br />
con<strong>text</strong>;consequently,apartionedsemantic<br />
networkwouldallowthesimpleconditions<br />
consult(u3),actor(u3;u5)andactee(u3;u6)to<br />
beboundtothreedierentboxes,whereas<br />
a<strong>scope</strong>dsemanticnetworkconstra<strong>in</strong>sthem<br />
toappear<strong>in</strong>thesamebox.However,this<br />
apparentlimitationisactuallyausefulsim-<br />
plication<strong>in</strong>anA-boxthatreiesrelations<br />
likedevelopandconsult.Inalogic<strong>text</strong>-<br />
book,thethreesimpleconditions<strong>in</strong>K3would<br />
typicallybecollapsed<strong>in</strong>toas<strong>in</strong>gleformula<br />
consult(u5;u6);<strong>in</strong>drtthenotationu3:<br />
consult(u5;u6)issometimesusedifthereisa<br />
subsequentreferencetotheconsult<strong>in</strong>gevent<br />
itself.Obviouslythiss<strong>in</strong>gleconditioncannot<br />
bedistributedamongseveralboxes,soouras-<br />
sumptioncausesnolossofexpressivepower<br />
comparedwiththenormaldrtnotation.<br />
4 Scopeconstra<strong>in</strong>ts<br />
Inwysiwymedit<strong>in</strong>ganA-boxisbuilttop-<br />
downstart<strong>in</strong>gfromtherootnode.Hav<strong>in</strong>g<br />
decidedthattherootnodeshouldbe(say)<br />
anentityoftypeimplication,theauthoris<br />
presentedwithafeedback<strong>text</strong><strong>in</strong>dicat<strong>in</strong>gthat<br />
anantecedentandaconsequentmustbespec-<br />
ied:Ifthissituationholds,thiscon-<br />
sequenceresults.<br />
Thephrases<strong>in</strong>boldfacearemouse-sensitive<br />
anchorsmark<strong>in</strong>gunlledattributes;byclick-<br />
<strong>in</strong>gonananchor,theauthorcanviewthe<br />
classestowhichasuitablellermaybelong,<br />
andchooseoneofthemtocreatetheller.<br />
Everytimeachoiceismade,thefeedback<br />
<strong>text</strong>isupdatedandnewedit<strong>in</strong>goptionsare<br />
oered.Bysuccessivechoicesonanchors,the<br />
authorcanbuildupacompletenetworksuch<br />
asgure2.However,aswehaveseen,for<br />
<strong>logical</strong>lycomplexmaterialastandardA-box<br />
suchasgure2is<strong>in</strong>sucient.Todenethe<br />
desiredmean<strong>in</strong>gcompletely,theauthormust<br />
somehowassign<strong>scope</strong>stotheoat<strong>in</strong>grefer-<br />
ents,as<strong>in</strong>gure4.<br />
Thecontrolof<strong>scope</strong>dur<strong>in</strong>gedit<strong>in</strong>graises<br />
severaltrickyproblems:<br />
1.Whenshouldtheoptionsbepresented?<br />
Shouldascop<strong>in</strong>gdecisionberequired<br />
wheneveranewentityis<strong>in</strong>troduced,or<br />
shouldthesystemallowthe<strong>scope</strong>tobe<br />
lefttemporarilyunspecied?<br />
2.Howcanthedecisionbepresented<strong>in</strong>a<br />
waythatnon-logicianscanunderstand?<br />
3.Howshouldtheedit<strong>in</strong>goperationsofCut<br />
andPasteaectscop<strong>in</strong>gassignments?<br />
Supposeforexamplethat<strong>in</strong>gure2u5<br />
wasassignedthe<strong>scope</strong>u1,whatwould<br />
happenifeitheru1oru5wereremoved<br />
fromthema<strong>in</strong>networkbyaCutopera-<br />
tion?<br />
4.Howshouldthesystemreactiftheau-<br />
thorattemptsanedit<strong>in</strong>goperationthat
wouldbeillegalunderthecurrentscop-<br />
<strong>in</strong>gassignments?Shoulditforbidtheop-<br />
eration,oroertheoperationoncondi-<br />
tionthatsome<strong>scope</strong>sarereassigned?<br />
Asanillustrationofthelastproblem,suppose<br />
thattheauthorhasconstructedthenetwork<br />
<strong>in</strong>gure2,exceptthattheactorarcfrom<br />
u1hasnotyetbeendirectedtothepatient<br />
nodeu5;andsupposefurtherthattheauthor<br />
(probablybymistake)hasboundu5tothe<br />
localcon<strong>text</strong>K3.Theresult<strong>in</strong>gfeedback<strong>text</strong><br />
mightbe<br />
Ifthispersondevelopsarash,apa-<br />
tientshouldconsulthis/herdoctor.<br />
Inwysiwymedit<strong>in</strong>g,anexist<strong>in</strong>gentitycan<br />
becopied<strong>in</strong>toanunlledattributebyselect-<br />
<strong>in</strong>gaphrasedenot<strong>in</strong>gtheentity(e.g.`the<br />
patient'),choos<strong>in</strong>g`Copy'fromthepop-up<br />
menu,select<strong>in</strong>gtheanchordenot<strong>in</strong>gtheun-<br />
lledattribute(thisperson)andchoos<strong>in</strong>g<br />
`Paste'(vanDeemterandPower,1998).Al-<br />
low<strong>in</strong>gthisoperationwould<strong>in</strong>stallthepatient<br />
astheactorofthedevelopactionu1;un-<br />
fortunatelyitwouldalsoviolatedrtscop<strong>in</strong>g<br />
rules,s<strong>in</strong>ceasimpleconditionactor(u1;u5)<strong>in</strong><br />
K1wouldnowciteareferentu5boundtoa<br />
box(K3)thatis<strong>in</strong>accessiblefromK1.<br />
Allfourproblemslistedabovecanbesolved<br />
(oratleastalleviated)by<strong>in</strong>troduc<strong>in</strong>gafur-<br />
thersimplify<strong>in</strong>gassumption:<br />
Everyoat<strong>in</strong>greferentmusteither<br />
beboundtotheouterboxK0,<br />
ormustbe<strong>in</strong>terpreted<strong>in</strong>situ(i.e.<br />
boundtothenarrowestofitspoten-<br />
tial<strong>scope</strong>s).<br />
Withthisassumption,theauthorneedno<br />
longerprovideanexactscop<strong>in</strong>gdecision;it<br />
sucestodist<strong>in</strong>guish`Global<strong>scope</strong>'(assign-<br />
menttoK0)from`Free<strong>scope</strong>'.Byadopt<strong>in</strong>g<br />
free<strong>scope</strong>asadefault,allwerequirefrom<br />
theauthorisadecisionoverwhichoat<strong>in</strong>g<br />
variablesshouldbeboundtoK0.Suchade-<br />
cisioncannotviolateaccessibilityconstra<strong>in</strong>ts,<br />
s<strong>in</strong>cetheouterboxisalwaysamongthepo-<br />
tential<strong>scope</strong>sofaoat<strong>in</strong>greferent.Itcanalso<br />
bepresented<strong>in</strong>awaymorefamiliartonon-<br />
logicians,asadist<strong>in</strong>ctionbetween`real'enti-<br />
ties,which(accord<strong>in</strong>gtothe<strong>text</strong>)denitely<br />
exist,and`hypothetical'entities,whichmight<br />
ormightnotexist.Referentsthathavebeen<br />
cuttothebuercanreta<strong>in</strong>theirglobal/free<br />
status,and<strong>in</strong>terpretedaccord<strong>in</strong>glyifthey<br />
arepastedback<strong>in</strong>tothema<strong>in</strong>network.Fi-<br />
nally,<strong>in</strong>thesituationdescribedabove,the<br />
patientreferentu5,withits<strong>scope</strong>leftfree,<br />
couldbecopiedwithout<strong>in</strong>consistency<strong>in</strong>tothe<br />
actorattributeonu1;byremov<strong>in</strong>gK2and<br />
K3fromitssetofpotential<strong>scope</strong>s,thisoper-<br />
ationwould<strong>in</strong>eectchangetheexact<strong>scope</strong><br />
assignedtou5fromK3toK1.<br />
5 <strong>Controll<strong>in</strong>g</strong><strong>scope</strong>dur<strong>in</strong>g<br />
edit<strong>in</strong>g<br />
Wenowshow<strong>in</strong>detailhowanauthormight<br />
constructthe<strong>scope</strong>dnetwork<strong>in</strong>gure4<br />
(equivalenttothedrs<strong>in</strong>gure3)bywysi-<br />
wymedit<strong>in</strong>g.Themethoddescribedabove<br />
hasbeenimplementedfully<strong>in</strong>theicono-<br />
clastsystem,whichgeneratespatient<strong>in</strong>for-<br />
mationleaets;forsimplicityweassumethat<br />
thesystemhasbeenconguredtogeneratea<br />
s<strong>in</strong>gle<strong>in</strong>structiononlyratherthanacomplete<br />
leaet.Onstart<strong>in</strong>ganewA-box,theauthor<br />
seesthefeedback<strong>text</strong><br />
Followthis<strong>in</strong>struction.<br />
imply<strong>in</strong>gthattherootofthenetworkshould<br />
besomek<strong>in</strong>dof<strong>in</strong>struction;ofcoursetheaim<br />
ofwysiwymtopresentsuch<strong>in</strong>formation<strong>in</strong><br />
ord<strong>in</strong>aryEnglish(orord<strong>in</strong>aryFrench,etc.),<br />
avoid<strong>in</strong>gtechnicaltermslike`network'or`A-<br />
box'.Open<strong>in</strong>gtheanchoryieldsalistof<strong>in</strong>-<br />
structiontypes<br />
action<br />
conditional<br />
procedure<br />
warn<strong>in</strong>g<br />
...
fromwhichtheauthorshouldselect`condi-<br />
tional';probablythesealternativescouldbe<br />
worded<strong>in</strong>awaythatwasmoreaccessibleto<br />
the<strong>in</strong>tendedusers,butwewillnotpursuethis<br />
issuehere.TheA-boxisnowupdatedbycre-<br />
at<strong>in</strong>ganimplicationentitywithundened<br />
antecedentandconsequent,andthefeedback<br />
<strong>text</strong>isregeneratedtoshowthenewedit<strong>in</strong>g<br />
options:<br />
Ifthissituationholds,thiscon-<br />
sequenceresults.<br />
Theanchorsmaybedeveloped<strong>in</strong>anyorder,<br />
butweassumethattheauthorclicksrston<br />
thissituation2<br />
allergic<br />
develop<br />
pregnant<br />
...<br />
andchoosesasituationoftypedevelop,thus<br />
specify<strong>in</strong>gthenodeu1<strong>in</strong>gure4.S<strong>in</strong>ceit<br />
descendsdirectlyfromacomplexcondition,<br />
u1isaxedreferent,sothereisnoneedto<br />
oertheauthoranedit<strong>in</strong>goperationforcon-<br />
troll<strong>in</strong>gits<strong>scope</strong>.Thefeedback<strong>text</strong>changes<br />
toIfthispersondevelopsthissymp-<br />
tom,thisconsequenceresults.<br />
whereupontheauthormightclickonthis<br />
persondoctor<br />
nurse<br />
patient<br />
pharmacist<br />
...<br />
andchoose`patient',thusspecify<strong>in</strong>gu5(g-<br />
ure4).Thistime,thenewlyspeciednode<br />
descendsfromasimplecondition,soitrep-<br />
resentsaoat<strong>in</strong>greferent.Thecurrentnet-<br />
workimpliesthreeboxes,l<strong>in</strong>kedtothenodes<br />
u0(theroot),u1(theantecedentofacom-<br />
plexcondition)andu2(theconsequent);by<br />
2Tosavespace,justafewalternativesareshown.<br />
CONSEQUENT<br />
ANTECEDENT<br />
develop<br />
ACTOR<br />
ACTEE<br />
u0<br />
u1<br />
u2<br />
implication<br />
u4 u5<br />
patient<br />
Figure5:Scopednetworkdur<strong>in</strong>gedit<strong>in</strong>g<br />
drtrules,u5couldbeboundeithertoK0<br />
orK1(represented<strong>in</strong>thenetworkbyu0and<br />
u1respectively).However,s<strong>in</strong>ceanewly<strong>in</strong>-<br />
troducedreferenthasfree<strong>scope</strong>,itis<strong>in</strong>itially<br />
boundtou1,thenarrowestofitspotential<br />
<strong>scope</strong>s.Theresult<strong>in</strong>gnetwork(gure5)is<br />
presentedthroughanupdatedfeedback<strong>text</strong><br />
Ifapatientdevelopsthissymp-<br />
tom,thisconsequenceresults.<br />
<strong>in</strong>whichthe<strong>in</strong>denitedescription`apatient'<br />
suggeststhatthe<strong>in</strong>structionisaddressedto<br />
anypatient,notspecicallytothepatient<br />
read<strong>in</strong>gtheleaet.S<strong>in</strong>cethisisnotthede-<br />
siredmean<strong>in</strong>g,theauthorcannowclickon`a<br />
patient':<br />
Cut<br />
Copy<br />
Global<strong>scope</strong><br />
Whena<strong>text</strong>spanexpressesanodeofspec-<br />
iedtype(i.e.itisnotananchor),theas-<br />
sociatedmenualwaysoerstheoptions`Cut'<br />
and`Copy';<strong>in</strong>addition,foraoat<strong>in</strong>grefer-<br />
ent,itoers`Global<strong>scope</strong>'ifthereferentis<br />
currentlyunconstra<strong>in</strong>ed,and`Free<strong>scope</strong>'if<br />
itisconstra<strong>in</strong>ed.(Aga<strong>in</strong>,wewilleventually<br />
wordthisoption<strong>in</strong>amoreaccessibleway.)<br />
Select<strong>in</strong>g`Global<strong>scope</strong>'modiesgure5by<br />
redirect<strong>in</strong>gthedottedarctou0,thusb<strong>in</strong>d<strong>in</strong>g
u5totheouterboxK0<strong>in</strong>thecorrespond<strong>in</strong>g<br />
drs.Mak<strong>in</strong>gthereasonableassumptionthat<br />
apatiententity<strong>in</strong>K0denotesthereader,the<br />
systemcannowupdatethefeedback<strong>text</strong>as<br />
follows:<br />
Ifyoudevelopthissymptom,this<br />
consequenceresults.<br />
Tocompletetheantecedent,theauthorclicks<br />
onthissymptomandchooses`rash'.<br />
Ifyoudeveloparash,thisconse-<br />
quenceresults.<br />
Thistime,thedefault<strong>scope</strong>assignedtothe<br />
newlyspeciedreferentu4isappropriate,so<br />
theauthordevelopstheconsequentbychoos-<br />
<strong>in</strong>g`obligation'andthen`consult':<br />
Ifyoudeveloparash,thisaction<br />
shouldbeperformed.<br />
Ifyoudeveloparash,thisperson<br />
shouldconsultthisperson.<br />
Atthispo<strong>in</strong>t,an<strong>in</strong>experiencedauthormight<br />
errbyclick<strong>in</strong>gontherstanchorthisperson<br />
andselect<strong>in</strong>g`patient'.Theresult<strong>in</strong>gfeed-<br />
back<strong>text</strong>revealsthenatureoftheerror:<br />
Ifyoudeveloparash,anotherpa-<br />
tientshouldconsultthisperson.<br />
anewpatienthasbeen<strong>in</strong>troduced<strong>in</strong>steadof<br />
referr<strong>in</strong>gbacktotheorig<strong>in</strong>alone.Toundo<br />
themistake,theauthorshouldselect`Cut'on<br />
thephrase`anotherpatient',sorevert<strong>in</strong>gto<br />
thepreviousfeedback<strong>text</strong>,andthenclickon<br />
`you'Cut<br />
Copy<br />
Free<strong>scope</strong><br />
andselect`Copy'.(Notethattherescop<strong>in</strong>g<br />
optionisnow`Free<strong>scope</strong>'ratherthan`Global<br />
<strong>scope</strong>',s<strong>in</strong>cethe<strong>scope</strong>ofthepatientreferent<br />
u5wasconstra<strong>in</strong>edearlier.)Click<strong>in</strong>gonthe<br />
anchorthispersonwillnowyieldamenu<br />
that<strong>in</strong>cludesa`Paste'option<strong>in</strong>additionto<br />
thelistofpermittedtypes:<br />
Paste<br />
doctor<br />
nurse<br />
patient<br />
pharmacist<br />
...<br />
Theresultofselect<strong>in</strong>g`Paste'isto<strong>in</strong>stallu5<br />
(thecopiedreferent)asthevalueoftheactor<br />
attributeonu3(gure4).<br />
Ifyoudeveloparash,youshould<br />
consultthisperson.<br />
Itrema<strong>in</strong>stodenethepersonthatshould<br />
beconsulted,bychoos<strong>in</strong>g`doctor'andthen<br />
past<strong>in</strong>g<strong>in</strong>thepatientaga<strong>in</strong>:<br />
Ifyoudeveloparash,youshould<br />
consultadoctorofthisperson.<br />
Ifyoudeveloparash,youshould<br />
consultadoctorofyours.<br />
Thedoctorreferentstillhasfree<strong>scope</strong>,soitis<br />
boundtoitslocalcon<strong>text</strong>u3(pairedwiththe<br />
drtboxK3).However,the<strong>in</strong>tendedmean<strong>in</strong>g<br />
isnotjustanydoctorthatthepatientmight<br />
have,buthis/heractualdoctor.Theauthor<br />
shouldthereforeclickon`adoctorofyours'<br />
andselect`Global<strong>scope</strong>'tocompletethenet-<br />
work<strong>in</strong>gure4.<br />
Ifyoudeveloparash,youshould<br />
consultyourdoctor.<br />
6 Conclusions<br />
Wehavearguedthreema<strong>in</strong>po<strong>in</strong>ts:<br />
Knowledgebases<strong>in</strong>nlgapplicationsof-<br />
tenfailtorepresentthe<strong>scope</strong>sofexisten-<br />
tiallyquantiedvariables.<br />
ThestandardA-boxused<strong>in</strong>loomand<br />
similarlanguagescanrepresent<strong>logical</strong>ly<br />
complexpropositionsifeach`oat<strong>in</strong>gref-<br />
erent'isboundbyascop<strong>in</strong>grelationto<br />
anaccessible`xedreferent';theresult-<br />
<strong>in</strong>gnetworkcanbe<strong>in</strong>terpretedasadrs.
Thetaskofconstruct<strong>in</strong>ga<strong>logical</strong>lycom-<br />
plexpropositioncanbeconvenientlysim-<br />
plied,foruserswhoarenottra<strong>in</strong>ed<strong>in</strong><br />
logicorknowledgeeng<strong>in</strong>eer<strong>in</strong>g,byrequir-<br />
<strong>in</strong>gonlyadecisionbetween`global'and<br />
`free'<strong>scope</strong>,withfree<strong>scope</strong>serv<strong>in</strong>gasthe<br />
default.<br />
Theseproposalshavebeenimplemented<strong>in</strong><br />
iconoclast,asystemthatuseswysiwym<br />
edit<strong>in</strong>g<strong>in</strong>ordertodenethecontentofpa-<br />
tient<strong>in</strong>formationleaets.Animportanttask<br />
forfutureresearchistoevaluatewhetherthe<br />
systemcanbeusedreliablybyour<strong>in</strong>tended<br />
authors|doma<strong>in</strong>experts<strong>in</strong>thepharmaceu-<br />
tical<strong>in</strong>dustry.Inparticular,weneedtocon-<br />
rmthatnon-logicianscandist<strong>in</strong>guishglobal<br />
<strong>scope</strong>fromfree<strong>scope</strong>,andtondouthowthis<br />
dist<strong>in</strong>ctioncanbemostclearlypresented.<br />
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