Ontology Development 101 :  A Gulde to Creatíng Your

First Ontology

Nululya F.  Nüy ami Dchoruh L McGuirmcss
Slunfurd [I...
of címe.  This ncpncsentalion includes the notions of (íme intcrvals.  poims in Iime.  relatíve
uneasures of iime.  and so...
an ontology arc different [mm the stmctune far a similar domnin in an object-oriented program. 

lt is impossiblc to covcr...
ptúduces

Chanau LIII!  ROIYISCNIU Pautlac

Flgnrc I.  Som:  chsm.  huzamos,  and rchtlou suton mert h thc wlnc Iormlu.  W...
Step 1. Determlne the domaln and scope of tha ontology
Wc suggcsl slartmg thc dcvclnprlncnl uf am cmlulug_y' hy drlining i...
Step 2. Conslder reuslng exlstlng ontologles

Il is nlmnxl nlxvuys xvurlh cunsidchng uhu!  surnwnc clxc hm dnnc und chccki...
thc wme class by crcating somc of its subclmses:  White wine.  Red w1ne.  Rosé
wine.  We can Íurther categorizz thc Red wi...
Slcp l.  m:  sclcct Ihc | L*l'I11.N Ihat dcwribc Objcclx husing inniopcndcnt cxisntncc ranhcr Ihzm lcrms
Ihnl dcscriho:  l...
0 rclaúonships m othcr individuals;  thcsc arc thc relationships bumm individual
uucmbcts of thc clms and odxcr itcms (c. ...
' Boolean slots am simplc ycs-nn flaps,  For cxamplc.  if wc ChODsC nm m rcprcxcnl
sparkling wmcs n;  a scpamtc class,  wh...
general:  all the classes ín the domain of a slor should be described by the

slot and insrances ofall the classes ín the ...
0 Malter:  ChIIcnu-Morgon (instnncc of the w:  ne ty class)
0 Regina:  Bcnnjolnis (inslnncc ofdrc Wine-Region class)
0 Sug...
3x mprcwming Ihc "kinő-ni" rclziiinnship,  (h:  mndrling crmr bcvnmrs chtur:  u singlc ÍŐÍJ",  is
nm a kind u! " hímes,  T...
must also be inslanocs of thc class B. 

4.2 Analyzíng síblings ín a class hierarchy

Siblíngs ín a class hierarchy
Slblln...
subclasses and.  indeed.  for the omology to reflect nhe different types of wine in a morc ommized
manner.  Medoc should b...
dcssen wines.  the Dessert w; nv_- class.  Thc Port winc is boch a red wine and a (lessen winef
Dmefotvc.  m:  dclim a cla...
modcrale winc.  and so on.  Whcn defming a class hieranchy.  out goal is Io strike a balance
bemeen cneating new classes u...
cluxs for cuch ni lhc rihx.  "Thal is.  if wc mint Io rcprcsvsnt dcluils udjuccncy and Incuiinn
infnrmulion Iwhich is diff...
9 Ö Wine radon 5

O United Stalas region*
0- Italian rsgion 4

9 French region*

8 Alsace iegion 5

Beauiolais rogion 5

9...
Exí-uí _n n:  : _ pcrfrurníing un cxpcrinvcííl mith his nunvc.  uflilmrinwn.  Cm),  l!  is Irur than zin
uxpcrííiícíilcr. ...
p:  ..  MÍLJ slm nf Ihc crurrcxpuwnniing H;  m.  1 y instmwc,  Fnr insmncc,  uhcn m:  xny Ihul Slcrling
kin-rím ix pruducu...
Drjínr a Imming rnnvrvztinrz fnr rlnxsc-xv ami xlnrx ami adhrre ln it. 
"Ih- Ínlltnning fenmnex uf u knnwvlealgc teprewuul...
6.3 Prefix and suffix conventions

Snmc Lnowlcxigc-basc nwthuxlnulrrgics suggcsl uxing prclíx und xuffnx CDIWLÍIIIÍDIIS in...
zlpplitállitíns m" thc nnmlnxxjy and (h:  dcsigncvs anndcrsxunding und wicw nf lhv:  dnmuín will
unndnubuvdly uffccl cnnnl...
NÍLTGUÍIIHxÍsS.  D. L..  Fikcs.  R. . Ricc,  J.  und XViIdcr,  S.  (2000).  An Environlncnl for Nlcrging und
Tcsting Lurgc...
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Ontology101

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Ontology101

  1. 1. Ontology Development 101 : A Gulde to Creatíng Your First Ontology Nululya F. Nüy ami Dchoruh L McGuirmcss Slunfurd [Inivcrsilya Slunfurd. CA. 94305 nnylfn smiuslunfxmLctlu und dlmO? "kxlmlsinfcircLcdu 1 Why develop an ontology? ln rcccnt ycars thc dsvcltypnwnt ni cmtnltigicx-cxphcnt formai xpcczticutimmns n! thc tcmm in thc dnmuin ami rclatmns minap: thcm (Gmhcr I*)')3 )-h.1.x bccn mnving írom thc rcalm of Artiiigiul- lntcllipcnc: lubnratnrícs to thc dcskmps ni dnnmin cxpcrls. Ontulnpxcs havc hccomc common on Ihc iNorld-Vkulc Wch. '11): nntologicx un thc Wcb rungc fmm lurpc laxnnomlcs cattguarizing Web sílcs ísuch as un Yuhoofl m CZIICfJIEFILIIIOILS o! pnxiucxs far snlc und lhcnr lculurrs (such as on Amamnusm). "lihc WWW (Ínmnruum HVBC; Ifs cicvclciping lhc Rcsmxrcc Dexcripuusn Fratnswwnnrk (Br1cklc_x' und GuhJ IWEH. u Imguugc for cncuding knowlcdgc un Wcb pagcs m mukc il undcrslzundahlc ln clcclmnit: ugcnls scurchíng Ím inlhrlnuliam. Tha- Dcfcmr Advunostd Rcxcurclt Pnvjcclx Agcnc) (DARPA), ín cunjulaclimm xsilh lhr W3C. is (irxclcrgaitig DARlÉ-X Agcnl hlurkup Languugc (DAML) by cxlcndirlg RDI" wilh morc cxpmxxixc cunslrtlclx uinxcd dl fuuiluuling qgclul inlcraclitnx un Ihu Wclv Illumllcr und hkfiuixmcss IÜÍIÜI. Álany dixciplínux mm dcwhvp slumkndi/ cd cmlulugicx [hal dgunaitw cxpcllx czm uvc ln shurx" und unmulanlc" infmixmliunt ín lhcír Üdds. Pvicdirinc. fur cxutruvlc. hm. prudtlccd kngc. alanulurdi/ cd. slrutluurd wuűvulurics xurh ux SYUMÉÍ) (Pricc ami Spuckvuuui Ziivfnln und Ihc- scnuuutic ncmurk of Ihc Unifícd Nilmíicul Laulgllugc Systunn (Hun-phwix ami Lindhu-rg I993l. Bmad gCnCIzlI-plllpíha" untuluxgívx arc eur-zuging sas m-II Fut exannple, thr United Nuriavns Dvvelnpiuieuxt Pmglaun und Dun &- Brndstlrel cumhínrd Ihcir effmtx ln dexelnup tha- UNSPSC unlnluigy uhich pnwidcs (rnninulngy fm pmxhnrh und senicex iwmvAnlsgvsxíuq! ). An unlnhvgy dvfíncx a cnmmnn mauhuLngxI I'm rcsozarchvrs whn nomád m xhurc infuí-rmuticm ín u (inmninx. II inuludcx nuxchinc-inrcrprctuhlc ciciinnitiivns nf hasis unnccpts in thc sinmuiui ami [Clunullx Jnwnng thcm, Why uuulx! somcnnc wunr m dcvclxwp aan nntnlngy"? Somos nf Ihc rcnmns arc: 0 Tv shurc cnmmnn undcrslandmg o! lhc slructurc o! mformuuon ananng pcoplc ur xuflxvurc Jgcnh - Tv enuhle reuxe uf daumuiui knnwledgr 0 Tn nmkc (lümuin axslnlnplinnx cxplncn 0 Tv scymrulc dommn knowlcdgc fmm thc (ipcrutítvnal knmvlcdgc 0 Tv ulml_wn' dumaiul knmw| cdgL' Shurma cummnn tomhvzvrrttriiil: u tiflin" uralt/ arc rg/ ilqtlnmmrfrvn rmumg [NWPJC nr A/ [flrzurc arc/ m ix onc uÍ lhc mmc cummon gnalx in duclopíng unluhtgics ÍMuscII I99I; Gmlm I993). FUI cxzunplc, suppwse; wwrzcl diffcrcnl Wich silcx Cnnluln nwdixvul ÍhfüfIHJIÍün nr pmxidc mrdicail c- ccxniw-snro: wniccx If thw: Wch sÍICN shun- und puhlish Ihc xunic umlcrlying unmlcwg) ní lhc Icmu thvy ull Llsf. lhcn cnnuptnkw agvmx czm CUÍHCI und ; n3g, rc_gulx' infrurnnxliniui fmm thcsc diffcrvnt silcs. TTw ngcnls cnn uw thix ZIgSÍPSJhKÍ infnrmutimt m nrmwcr uscr qucrics ar us input dzna m mhcr appliczitinns FnuhIinIu rruxr "f" rhmurir: ÁHr/ lrhúigjr" wus nnc of Ihc (Iriving fu-rccx hchind reucm surgc in (imola-gy rcwmrch. Fnr cmmplc. nuwdcls fnr nmny diffcrcnt dnnmins nccd m rcprcxcnt thc nminn
  2. 2. of címe. This ncpncsentalion includes the notions of (íme intcrvals. poims in Iime. relatíve uneasures of iime. and so on. lf one group of reseauthers develops such an onlology in detail. othcrs can simply rcuse it for thcir domains. Additionally. if we necd to build a large omology. we can integrate sewnl existing ontologies describing portions of Ilie Iargc domain. We can also mm: a gcncral ontnlogy. such a; thc UNSPSC ontnlogy. and cxtcnd i! no dcscribc out domain of intcrcsl. Makíng explicit dnmain assumptinns undcrlying an implcmcntation makcs it possiblc to changc Ihcsc msumptinns casily if our knowlcdgc nboul lhc domaín changcs. Hartl-coding msumplims about lhc world in prognmming-langungc codc makcs thcsc assumptíons not only hard to End and undcrsmnd but also hard to changc, in particular for somcont without programming cxpcrtisc. ln ndditim. explicit spccifications of domain knowlcdgc arc uscful fut ncw uscrs who musx lcam whm tcnns in tbc domain menti. Sepamting lhe domain knmvledgc fmm the operatívan! knoivledge is anothcr common uu: of ontologics. Wc van dcscribc a uisk of cunligtiring a pmducl Írom ils compuncnls arccording (o a mquirod spocifícnlion and implcmcnl a program [hal clocs this cunligumion indcpcndcnl of tbc producls and componcnls lhemselvu (McGuinness und Wrighl 1998). Wc can then dcvrelop un onlology o! PC-componenls and chanmeiislics und apply lhc algorilhm lo configure mink-lo- ordcr PCs. Wc cau also usc lhe same algorilhm lo conligure elevalors if we "Íeed" an elevalor componenl ontology lo i! (Rothenlluh e! al. 1996). Analyting dumain knovrfedge is possible once a declarative specification of the terms is available. Forma! analysis of temis is extremely valuable when bodi anempting (o reuse existing ontologies and extending Ihem (McGuimiess e! al. 2000). Often an ontology of the domain is nm a goal ín itself. Developing un ontology is akin to defining a se! o! dala and lheir stmctune for other program to use. Problem-solving methods. domain-iruiependent applications. and software agents use ontologies and knowledge hasas buill [rom omologies as dala. For example. in lhis paper we develop an ontology of wine and food and appmpriate comhinatirms of wine with meals. This onmlogy can then h: used as a hasis fnr snme applicaxions in a suile of rtstnurant-nunaging tools: OM applicalion could create wine suggcstiom I'm the menu of the day nr answer qucrics of waitem and customcrs. Amther application muld analyu an invcmory list of a winc ccllar and suggcst svhich winc catcgorics m cxpand and which parlicular wincs to purchasc far upcoming mcnus or cmkbooks. Aboul thls guldc We build on out experience using Procégé-Zom (Pnxcgc 2000). Omolingua (Ontolingua I997). and Chimaera (Chimacra 2000) as onlology-editing envimnmenls. ln lhis guide. we use Prolégé-Zülo for our examples. 112 wine and food example Ihat we use throoglmm this guide is loosely hasad on an example knowledge base presemed in a paper describing CLASSIC-a knowledge-representaiion system hasad on a dcscription-logics approach (Brachman c! al. l99l ). The CLASSIC tutorial (McGuinness e! al. 1994) has developed Ihis example funher. Proiégé-Zom and other frame- bascd systcms dcscribc onlologics dcclaralivcly, suuing cxplicitly whul the cluss hicrarchy is and to which classes imlividuals belong. Som: ouIology-design ideas ín lhis guide originaled Írom tbc lilerature on object-orienled design (Rumbaugh e! a]. l99l; Booch c! al. l997). Howtwr. omology dcwelopmrm is difit-rum Írom designing clmses and rclanions ín object-orienxed programming. Object-oriented programming centem primarily around melhods on cIasses-a programom malses design decisions hasad on lhe operarionczl pnoperlics o! a class. whereas an ontology designcr malac-s these decisions 515001 on IM smrcrurcil propenies of a class. As a nesuli. a class slmcture and relations among classes in
  3. 3. an ontology arc different [mm the stmctune far a similar domnin in an object-oriented program. lt is impossiblc to covcr all tbc issucs tbat an onmlogy dcvchpcr may nccd to grapplc witb and wc arc not trying to addrcss all of tbcm in this guidc. Instcad. wc try to pmvidc a srarting point; an inilial guidc ihat would hclp a ncw ontology dceigncr to dcvclop omologics. At thc cnd. wc suggcst placca m look fnr cxplanaticms of mm: complicatod structurcs and design mccbanisms íf tbc domain rcqtiircs thcm. Finally. thctc is no singlc corrcct ontolngy-dcsign mctrtodnlogy and wc did not attcmpt m dcfinc onc. Tbc ídcas tbat wc prcscnt hctc nm thc nncs that wc Íbund uscful ín our own ontology- dcvclopuncnt cxpcricncc. At tbc cnd of this guidc wc suggcst a Iist of rcfcrcnccs for altcrnalivc Incthodologics. 2 What Is ln an ontology? The Artificial-lntelligeutoe Iiteratmc cootnins many definitions of an ontology; many of these conuadict one anotber. Fut tbc purposes of this guide un ontology is a lommal explicit aiescription of conccpts in a domnin of discoursc (clnsscs (somctinncs callod conccpm). prupcrtics of cnch cnnccpt dcscribing various fcatuncs and nttrihutcs ol' tbc conccpt (siet: (somctimcs callcd mlcs or propcrliesn. and rcstrictiom on sincs tfnceís (somctinmcs called rolc rcstrictiocsn. An ontology together with a set of irtdividual Instanccs of classcs coustitutes a howledgc basa. ln rcality. merve is a fme line wbere tbc omology ends and tbc knowledgc basa begins. Clatsses arc the focus of most ontologia. Classcs describe concepts ín the domain. F0: exantple. a class of wines tveprveseuts all wines. Speciftc wines arc instances of this class. Tbe Bordeaux winc in tbc glass in front of you whilc you rcad this documcnt is an instancc of tbc class of Botdeaux wincs. A class can hava slbclamcs Ihat rcprcsent conccpts Ihat arc ntore specific tban tbc supetclass. For example. wc can divide tbc class of aII wincs into red. whitc. and rosé wines. Altematively. we can divide a class of all wines into sparkling and non-sparkling wincs. Slots describe properties of classcs and instances: Cháteau Lafite Rothschild Pauillac w-inc has u full body; it is produced by tbc CháLeau Lafne Rothschild wíncry. Wc havc two slots dcscribing tbc winc in this cxmnplc: thc slot body witb tbc vala: ÍuII and tbc slot makcr wítb tbc valuc Cháteau Lafate Rothschild wíncry. At tbc clmss Icvcl. we can say tbat irtstances of the class wi ne will havc slots dcscribing thcir tldvor. body. sugar level. thc maker o! thc wine and soon. ' A]! instnnccs of tbc clnss wine. and its subclms Pauillac. hant a slot make: tbc valuc of which is an instancc nf tbc class Winery (Figunc l). AII instanccs nf tbc class Wincry bavc a slot produces that rcfcrs to all tbc wincs (instanccs nf tbc cum Winc and ím suhclasscs) tbat tbc wincry produccs. ln practical temts. developing un ontology irtcludm: 0 dcüning classcs in tbc onlology. 0 arranging tbc clnsscs in u taxonomic (subcltnss-supcrclass) hicrarchy. 0 dcíining slots and describing allowed valucs for tbc-se slots. 0 tílling in thc valucs for slots for instanccs. We can thcn crcatc a knowledgc basc by dcfining individual instances of tbese classcs filling in spcciftc slm valuc infonnation and additional slot rcstricticms. ' Wc cnpitalizc class namm und sut! slot namcs with low-casc Icmcrs. Wc also usc Lypew: i: ex iont for all ocnns írom tbc cxunpk ontology. b)
  4. 4. ptúduces Chanau LIII! ROIYISCNIU Pautlac Flgnrc I. Som: chsm. huzamos, and rchtlou suton mert h thc wlnc Iormlu. We und hhclt tor eltartsam! rcdhrhslancu. Dlrcclhhrcpruurtdotsandlntcrmlhhmdnulnstancc-dsnd mit-hadat. 3 A Slmple KnowIedge-Englneerlng Methodology As wc mid carlier. therc is no (ne "oorrcct" way or methodology for developing ontologies. Here we discuss gcneral issues to consider and offer one possible prouess for developing an omology. Wc describe an itcrntivte approach to outology development: wc start with a rough lirst pasa at tbc omology. We tben revise and reliue thc evolving ontology and Iill in thc details. Along tbc way. we discuss thc modcling decisions that a designer nccds to make. as wcll as tbc pttos, cons. and implications of diffcnent solutions. Füst, we would like to emphasizc som: Íundamcntal rules in ontology design to which we will rcfcr many timcs. Thcsc rulcs may sccm mtbcr dogmatic. Thcy can hclp. howcvcr, m makc design dccisiom in many cascs. I ) Therc is na nne correct way m model a domain- there arc aha-ny: viable alternatíva. The bar! xnfution almost always depcnds (m the applícarion Ihat you havc in ntind and thc cxrcnsions rha! you anticipatc. 2) Ontologtt dcr-elopmenl is necessarily- an íreruliw- pracess. 3) Concepls ín thc onmlogyv should be close w abjecLr (pírt-sicc! ur logical) and rclationxhip: r'n yrmr domain af interenrt. Thcse arc mart likely lo be nemu- (objecls) or verbs (relationships) ín senrenccs Ihat dcscríbe yout domaiir. Tbat is. deciding what we nne going to usc thc ontology for. and how detailed or general thc ontology is going ro be will guide many of thc modeling decisions down the road. Among seveml viable altematives. wc will need to detemúne which one wnuld work better for thc projected task. be morc intuitíve. morc extensible. and Inota maintainable. We also need to renrember that an outology is a tuodel of reality of tbc world and thc concepts in thc omology must reflect this reality. After we dcünc an initial version oÍ tbc ontology, wc can evaluate and debug it by using it in applications or problem-solving methods o: by discussing it urith expens in thc Iield. or both. As a result. wc will almost certainly neved to revisc thc initial omology. This process of iteratitre design will likely cootinue througb tbc amire Iifecycle of tbc ontotogy.
  5. 5. Step 1. Determlne the domaln and scope of tha ontology Wc suggcsl slartmg thc dcvclnprlncnl uf am cmlulug_y' hy drlining ils duruuinn und wups. That h. answcr scvcml hasit qucstíunx: * XVhul ix thc dnnlum Ihul thc Onlnlngy will centi"? 0 l-ior whut wc un. - gming 10 usc thc ontolugy"? 0 Fur uhut typcs tvfqucsliuuts lhr infommliun ín (h; (vnlulugy shvuid prmidc unxxvch? 0 Whn will uxc und muinlznin thc nnlnIaxg_y'? Th: anmcrx m Ihcsu Rtlcslinnx nuty chgmgt: during thc: tvnlnlngyrxicsign pmccsx. hm a! amy giwn Iimc thc; hclp Iinmil thc scnpc nf thc Inmlcl. (Rwnxiticr thc onlnlugy uf winc und Inod thut wc inlroduccd carlicr. Rcprcwclttutiun 01' Ilmtl and wincs is thc domain n! thc cmtnlewgy. Wc pLm m usu: lhis nntnlngy for thc apphcatinwtts thal xuggcst gond conxhinalimwlms of XVIÍICs und Ilmd. Nuturally. thc conccpts dcxcrihing díffcrcnt lypcs nf umcx. main fond typcs. thc nntimt oÍ u gnod cumbinalitwn nf wmc and fond and a had comhinutinn will figura imo our omnlogy. A! thc sumc tímc. it 1- unlikcly that thc omnlogsy wíll Includc cnnccpts for manapmv mvcmnry in a wmcry or cmployccs in a restaurant cvcn thouph thcsc cunccph arc xonxcwwhat rclatcd to m: nmmns o! " wmc zunl fond. lÍ thc tmtology wc un: dcsigmn: will b: uscd to xtsslsl m nnturnl languagc pruccssmg: ol antclcs in uinc nuguzincs. it muy be nmponunt m íncludc synonywus und parl-OÍ-spccch inibnnulitvn for cunccpts in thc ontolugdv. If thc onlology will be uxcd tu hclp mxtatimnl custunwrx dccidc which winc to urdcr. wc nccd tv includc FCIJÍI-prifing infunnntion. If Íl is uwd for winc buycrs in xlucking a winc ccllur. wholcsulc prícíng und uvuilahilily muy bc nccusxnr): If thc pcupl: uhu wíll nmjnluin thc unlnlog_x' dcstTihc lhv: donmin m u Iangungc lhnl is diíícrvnt Írom thc lunguagc uf thc unlulogy uscrs. we muy nccd lu provldc thc umpputng hclvxccn thc languugcs. Connpetency questions. Ont uf thc wuys 10 dclcntiinc thc wupc of thc untology 1x [u xkclch u lixl of qucxlions thul u knoxivlcdpc basc huscd un thc Onluiüg)" shuuld be ablc to nnswcr. tompult-ne)" qucstíons (Gruningcr und Fux 1995 t. Thcsc qucstíons W! " scrvc us thc lumus test Iulcr: Dvocs thc ontnlopy cunmin cnnuvsh ininmmtinn lo answcr lhcsc typss uf qucslionw Dn thc nnswcrs rcquirc a punicular Icvcl nf dctuil nr rcwtscntalinn of a pnniculur arca? 'I'hc. wc cnntpclcncy qucxlicms arc jusst a skctch and do not nccd to be cxhuustivc, ln thc winc und fond domxtin. thc follomnp arc thc POASIhIC compctcncy qunnons: 0 Which winc chdrauclrrisllcx slmuld l cumid-n whcn chouxing a winc? ' [s Bmdeuux a rad nr whíle winr? 0 Dncs (Iahcmct Suuvignon gu wcll wíth scafood? 0 Whul 1x lhc láncai clmícc uf WÍIIC I'm gnllcd mcul? o Which chuructcuixlicx ofn uvinc anffccz its '. tpprl'tpriztlcncxs fnr n dish? 0 [kacs a houqucl nr body ni a spccilic winc chunpc wilh vinlayc ycnr? 0 What wcrc gond vinlugcx for Napi Zinfundul? Judgíng Írom lhix hsl uf qucxlions. (ha: ontulugy will includc thc infunlmlittn un vunoux winc chumclcxislícx and winc lyptm. xinlugt" ycurs-gnvtxi and had un: s-clausxilículitnts uf Ilvuds (ha! ntaucu- fur chuoxing un Alpplxtígriulg" u-inc, rccmuunnnrtidrd conubinutixvns nf u*iltt' und fond. ÍJI
  6. 6. Step 2. Conslder reuslng exlstlng ontologles Il is nlmnxl nlxvuys xvurlh cunsidchng uhu! surnwnc clxc hm dnnc und chcckirlg rf m: cnn nrfmc and exlcnd cxislilng suurccx fur uur pautrculnr dmmírx und lerak. Rcusing cxislirlg unlnlugics nmy be n It-quircnzcnl iÍ uur xynlcm IYCCtÍN lu inlcrucl wilh ulhcr upplítulivns lhul huvc ulrcuchv cummillcd lu purlíctnlnr unlultvgics or cunlrullcd uwuhulurics. Muny tmlukrgicx arc ulrcad_x' uwilnhlc in elcrtrnrlík" fnnn und cun ha Ílllpüfftd inna un nnruluagy dewreIcvpnn-nt envircvnlnem thnl ynn ure using, The furmznlisnn ín which un canlnlmrgy is expreswxl cuflerm nincs nm nunxer. since nmny knuwIrdge-rrplewnlulítln xyxleuns cnn impcm ami cxpnn (mlolngies, [íven ifu kumwlerlgr- rcprcsvnlulinurm syslcn) cunmnr mark dircrtlly wilh u paniwlur furmulisnn. thc Iaxk uf rrnnslznling un nmulngy Iram nnc fHImAIIÍsIIl ln smnthcr is usuzslly nm . n diflícnnll anc. Hxsrc sarc Iíhrurics ní rcumablc OIHOIIVgÍCN un thc SVch und ín Ihc litcrnlnrc. Fur cxsnnplc, ne czm uso Ihc Omnlingutn nmnlngy library íhuy Hun xx LxI. xlzmfc'-rxÍ, x'rÍjlg'xl'vfl u Lfg/ r!I1I()IÍI11'_II;1Í) or Ihc DAMI. nnlolugy Iibmry Igya Hu xs n . (I;1Í1_T]_lgLs_'_-'n|1[liIIH'_Ít"§-'A). Thcn: arc also a numbcr n! " public-lyv avuilzxhlc comnvsruinl nmnlrxgncs log- LYNSPSC Iu-u'u'.1|I1s'psu. crr-g)_ RnscuuNcl (wxuv. mxcllanclxvrg L DMOY. (wxvxxudmnuxrg I). Far cxumplc, u knnnlcdpc hasc nf Frcnch nincs mny alrcady cxist. lf wc cnn import nm knowlcdpc hasa: and thc onlrllrsggxl m1 which n lx hascd. m'c wnll havc nm only lhc classnlicalion of Frcnch wincs hul qISO thc üm pnsx a! 1hc claxsilicution of wmc ch. 'nruclcrisucs uxcd lo drsxíngunxh and dcscribc thc viincs. Lusta o: w-ínc prnpcnics mny Jlrcady be uvnrlablc Ímm commcrmal Web sncs such 4x xx-xvxnzxx1r1cxcrnn1 Ihat customcrs consxdcr usc to buy wíncs. Far uhu guidc howcvcr wc will Jxsumc uhut no rclcmnt cantolvgucs ulrcudy cxisl und mm dcvcloping thc ontom-gy frum xcmlch. Step 3. Enumerate important terms ín the ontology It Íx mán] m wnlc dnwn n IM nf ull tcrnh m'c wnnltl Irka: cithcr m mnkc snatcwcnts nhnut nr m cxplain m u uxcr. Whul urc lhc lurmx wc wnuld Iikc m mlk Jhnul"? What prnpcnics do thcm: lcrms hnvc"! Wha: vmuld wc lika: m xny Jhnul rhmc rcrmx"! Far cxgamplc. ÍIITPDILIIII winc-rchncd lcrms will includc "m. Clnaué. .. *1'x: r-r[. w', lC-': .': T1='. r.. u winck xWlr-x. t'z. w,iv_x. f] rag: and ; _: , x:_: ,.r . , m, _í'uL. (lilTcrcnl typcs cirf L 4 Nuüh us A i un und 5_111 r" , m: sublypfx o! " winc xuch as v. vr. -.: : van nnd so on. Inilinlly. i! is impunanl lo gcl u cumprvhcnsivc liwl uf lcrms uwthout wnrrymp ahour ovcrlnp hclwccn cnnccpzs thcy rcprcscnl. rclanons anmnp thc rcrmx. or any pmpcmcs thnt thc cnnccpts muy havc. or whcthcr thc cnnccpts arc classes or slnts. Thc nrxt two stcps-dcvcloping thc class hrcrnrchy and drfímng: propcmcs m concepls (sima)- arc closcl_x' mtcnxvincd. lt Is hurd tn do onc 01 thcm frrst and lhcn do thc mbar. Typrcallyz wc crcnlc a fcw ciclinilitvns of thc conccptx ín (h: hlcrntthy and lhcn continuc hy describmg proputicx o! " lhcsc conccpls and m (m. Thcsc two slcps arc alxo lhc most imp-nrtanl slcps ín thc unloluggv-dcxigr1 pmccax. W: wíll dcscrilvc thc-m hcrr hricfly und lhcn xpcnd (h: nm! nm scclimvnx drscuxsíng (ln: morc cnmlplrunlcd ixsucs (ha! nccd ln ha uonsidcrul. cummon pitfulls. dccísicvnx lu mukc. und w un. Step 4. Define the classes and the class hierarchy Thcm arc scvcral posszhlc upprmchcs m dcvclnpinp a class hirrarchy (Líschold ami Grunirmgcr WÜÓ): - A top-clown dcvclopmcnl pmccss srans wíth thc dcfmiuaan of thc nunst pcncral conccpls ín thc dommn and suhscqucnt spscíalizatirwn of thc conccpts. Fnr cxantplc. vuc cnn start wnh crcating classes for thc pcncral conccpts of Hírt" and Thcn wc spccialim
  7. 7. thc wme class by crcating somc of its subclmses: White wine. Red w1ne. Rosé wine. We can Íurther categorizz thc Red wine class. for exarrple. into Syrah. Red Burgundy. Caberne: Sauvxgncn. and so on. 0 A boltom-un dcvclopmcnt proccss stans with thc dcünition of thc most spccifnc classes, thc Icavts of thc hicnmrhy. with suhscqucnt gmuping of thesc classes into morc gurum] conccpts. For cxnmplc. w: start by delining classes for Pauil lac and Margaux wines. We then erezne a common superclass for these two cIasses-Meaoc-which in rum is a subclass of Bordeaux. 0 A colblnndou devclopment process is a combination of thc top-clown and bottum-up approachcs: We dcfme thc morc salient conccpts lirst and thcn generalizx and specialiu them approptimely. We might start with a few tora-leve! conoepts such as wine. and a fcw spcciíic conccpts, such as Ma rqaux . Wc can thcn rrlutc thcm to n middlc-Icvcl concept. such as Medoc. Then w: may want to gencrate all of thc regional wine classes from Franoe. thereby generating a number of middle-level ooncepts. Figura 2 shows a possible breakdown among the different levels of generality. O O Rosé Mne 9 O Red van: C Bewjolals O O Red Burguncy O Red zinranuet 9 Ó Red Bordeaux 9 O Hedoc O Paullac O Margaux O St Emlllon O oraves O Cabernet Franc O Cabernet Sauvignon O Plnot Noir O Chtantt O Pelrte Syrah Ó Semerre C Muscadot Figura 2. Ti: dIIereII levek o! thc lánc Iaxooorly: Ilino Is thc most gazra! centem. Ind van. amit. vino. und noni vino un gencnl top lrvcl cuncepts. Dauinac und Iatqnux arc thc most spedflc classes ln thc hlerarchy (or thc botlom leve! conccpts). None of these three methods is inhcmntly bettcr Ihan any of thc others. The appmach to taltc depends strongly on thc persona! view of thc domain, If a developer has a systermtic top-down view of thc domain. thcn it may be easicr to use thc top-clown appmach. "Dac combination approach is ottan thc casiest for many ontology (IGVGICIpCIS. since thc concepts '*in thc middle" tcnd tn be thc morc descriptive cnnccpts in the dnrrtain (Rosch 1978). If you tend to think of winee by distínguishing thc most gcncral CIaSíEÍÍÍCaIÍOII tírst. then thc top- down approach may work better for you. If you'd rather start by getting gmunded wíth speciüc examplcs. thc bortom-up appmach may be morc wpropriate. Whicbever approach we choose. we usually start by defining classes. Fmm the Iist erezned in
  8. 8. Slcp l. m: sclcct Ihc | L*l'I11.N Ihat dcwribc Objcclx husing inniopcndcnt cxisntncc ranhcr Ihzm lcrms Ihnl dcscriho: lhosc nbjccts. Thcvc lcnm will be classes ín uhu: (Intnlugy ami will bCCnITvC anchuwrs in Ihc Clslxs hicrarchy: Wc orguni/ vc lhc classes inm u hicrurchical laslnnnmy by asking if hy being . m inxtsmuc nf nnc cLm. thc cvhjcct vxill ncccwurily (i. c.. hy tlctínitignn) be zm insnmcc of sn p: olhcr clusx. If u cluxzr A m u . VII[JC'I'(ÍÍU. V,V of Hun" B. Ihcn crcry inxtruzc c nfB i; (1141.: un insnuxrr nfA ln olhrr xwnlx, the elem B represenlx u oxmmcs-pl lhnl ix a "kim! u! " A. Fut exunlple, es-ery Finn; Nnir winr is necesmuily n red wine. Therefuvre tb: - -_r. Í-"Ji : aflam is u xubcluss uf lhc Ha : . "vég-n; class. Fipurc 2 shmvs u part 01' thc clasx hícmrchy for thc Winc ontnlnpy. (Scctinn 4 cnnluins a dctailcd discuswíon of (hints lo Iook for whcn dcfimnr: u class hicrurchy. Txypr- V l: árum anrr | ÍZhv*-r rnrwis Symbxr smgle ' 'ues= iFIJLLJJECIjLII-jl; JHT: Svmbui sin ule Tlowed-vyues iREDROSEJruX-HTE) Symbuf sír glu rlowud-vruuFIDELICATE. MODERATESTROPJII+§ | n=tm Ti? " mu 1Ip'r- ch a r r-: *.= i'v'dIn-1 gmp P] ln stanze smgle class. es=4'rdlner, '; Sir wg sin gle Swmbc sír gin J lovagra-v; *uo; e mi] R'1', S'u'vEET,0FF-E1 m"; Figura J. Thc slols fur IIM: class WLne and thc fara-La for thcsc slots. Thc "l" icon ncxt to the malter alul ímlicnin Ihnl the slnl hm un ima-n: (Su-licon 5.1) Step 5. Deüne the properties of classes-slots 111.: classes nlonc u iII not providc cnnuglm infnmutinn m nnswcr thc cnwpclcncy qucsxinns fmm Stcp l. Oncc wc hun: (ictincd snmc nf thc clmxcs. wc must (icscrihc thc intcmul unwturc of crmccpts Wc hzm: nlrcudy sclcclcd classes from thc lisl of tcnm wc crcalcd ín Slcp 3. Most of thc rcmainnnr icmu arc likcly m bc prnpcnicx 01' lhcxc clusscx. Thcsc lcrms includc. for cumplc. a wnnck v: 1 r, tv: .u. .1g. v, z l. '1'. '.'1l' und -. : , )rI_1-'1L' rmr r nT and 1 a r. i of a wmcry. Far cuch prnpcrty in thc Iisl. wc must dvlcu'minc which Clnsx iI dcwrihcsv ThCsC pmpcrlics bccnnm-s slnts atrnchcd m classes. Thus. thc k" x m; class will hava: thc follmving slots: 1 1.: L. - , body. f 1 ÍNJC r, und : 1. qa r. And lhe class iiir: ry will lunc a l r: :at. ion xlul. ln gcncral. (harc arc scvcrul typcs of objcct prupcnics ihat van bccomc sIOts ín an ontolngy: ' "ínlrinsic" prupcnícs such as thc : ' 1 . ár uf a xsinc: 0 "uxlrinsic" pmpcllivcs such ux 4 minek tea-ne , und nrea il (tllllcx fnnn; 0 punx. iÍ lhc nhjccl is slructurcd; 1hcsc cun be hulh phyxicul und ubslmd "paris" (mg. lhc cutlncs uf a Indul) 3 W; - cun ulw xicw Manus m unury purdnculcs-q ucslitku Ihat hun: unt urg-umcnnl. Fv-r cxumpls, "Is Ihis (xbjwn . . mint! " Límry prulicuzn-x mr CLLMCNI canmm uixh binnry prcdículcx mr sIrlsl-qucslintla (ha! haw nm argumcms. Fnr cxqntvplc. "Is thc flavnr ofthls objcct stmng" "What Is thc mvnr n? this nbjcct , '"
  9. 9. 0 rclaúonships m othcr individuals; thcsc arc thc relationships bumm individual uucmbcts of thc clms and odxcr itcms (c. g.. thc maker of a winc. rcprcscnting a nelationship hetween a wine and a winery. and the c; rape the wine is made fmm. ) "Ihus. in mklition to the propcrlics we huve idemilied earlier. we siesd Io add the followíng slols lo the wi ne class: name. area. malter. qrape. Figmve 3 shows the slols for the class Wine. AII suhclasses of a class inted! the slot of ma! class. For example. all the slots nf the class Ni ne will be inherited to all subclassas of Wine. including Red Wine and White Nine. We will add an uddiüonal 5101, tannin level (Iow. madarain. or high). lo thc Red wine class. Thc. tanni n leve] slot will hc inhcritcd by nll thc classes rqurcscnting tcd wincs (such as Bordeaux and Beaujolais). A slot should be atlachcd a! thc most gcncml class (ha! can havc [hal propcrty. For imlancc. body ami color of a wine slwuld be unachcd u! the class Wine. since i! is thc most geneml dm whosc insmnccs will huvc body and mint. Stop 6. Donna the iacets o! the slots Slots can have different faoets desctibing the value type. allowed values. the number o! thc valucs (cardinality). and othct Íeaturcs of thc valucs thc slot can takc. For cxamplc. thc valuc of a name slo! (as in "the name of a wine") is one suing. Thal is. neme is a slo! with value type Suing, A slol produces (as in "a winery produ ces chese wines") can have mulliple values and thc vnlues arc imtanccs of thc class Winc. "Flint is. prcduces is n slot with vnluc type Instance with Wi ne as allowed class. We will now describe sava-a] common fucets. Slot cardinality Slo! canlinalily defmes how meny values a slot van hava. Some- syslenm dislinguish ouly belween single cnrdinalily (allowing ut rmsx one value) and mulüple cm-dinnlity (allowing any number o! values). A body of a wine will be a single cardinalily slut (a wine czm haw only ooe body). Wincs producod by a pnnicular wincry fill in n muItipIc-cnrdinality slot produces for n Wi nery class. Some systems allow specifncatioui of a minimum and maximum camdinality to descríbe thc number of slot values mone prccisely. Minimum cardinality of N means dm a slot must have a! Ieast N values. For exnmple. the grape sloí of a Wine has a minimum cardínality of l: each winc is madc of a! Icast onc varicly of grupc. Mnxinmm cardinality of M ntuns Ihat a slot can huvc a! most M valucs. Thc maximum caniinality fut thc grape slol for singlc vurictal wincs is l: thcsc wincs arc nmdc fmm only nnc vnricty of grapc. Sotnctinncs it may be mcful u) sct thc maximum cuminnlity m 0. This scuing would indicntc Ihat thc slot cannot hava: any valucs for a panicular subclass. SIot-value lype A vaIuc-lypc faccl dcscribcs whal lypcs nf valucs can Íill in thc slm. Here is a Iíst of thc morc common valuc typcs: 0 Slrlng is the simplesl vnlue lype which is used for slots xuch as name: the valuc is a simpk slring 0 Number (somctimcs morc sptciüc valuc typcs of Hont und Integet arc uscd) dcscribcs sincs wilh numeric valuta. For exanmle. a príce of a wine can haw a value lype Flozu
  10. 10. ' Boolean slots am simplc ycs-nn flaps, For cxamplc. if wc ChODsC nm m rcprcxcnl sparkling wmcs n; a scpamtc class, whcthcr or nm a winc is spaxklinp can be rcprcscntcd m; a vuluc o! u BCKTÍEHII xlm: if (hc vuluc is "lruc" Pycs") (h: winc is spurkling und if thc vuluc IS "falsc" Pun") thc wmc is not u sparklmg ont. 0 Enumcralcd sluis spccify a Iisl uÍ sirviűc ullivwcd valuta. for lhc slol. For cxmnplc. wc cun sp: cil'y' lhul llic f luvcur slul cun lukc un unc of thc lhrcc pwsíbls- iuluuv le r g t e, and de ; ; . : a t e. ln Pmlégé-ZULJO thc cnumcmlcd slots arc of lypc L? J "P gjr i? * Imtanccágvpc slots ullow dcfmitmn o! ICÍHIIOHShIpS bctwccn individuals. Slms urilh vuluc typc lnxtuncc must uhu dcfmc . i Ihl of allowcd classes fmm which thc instunccs can comc. For cxumplc. a xlut p- : ::; iun_': ;. for thc clau m r r: r", muy huvc instnnccx of thc class H 1 FIP as ilx mlucsŐ Figuie 4 shnwx a deűuiiticun ofthe xlm pipa-m : u! the trlazss 111" 11.§" ni. 'I proűJcnr Thrs ami (untam-s the wnes DIOCJCEU bv a part cLJar xvinen] 1 1 + u _ ' C "Ti"? A tequired a! lenni r munímu a! mosli Flgure 4. The tlennltkm of a ssIul ptoduccs (hal dcxrrlhes the wlnes pruduced h) a icirit-na Tlie sin! has cardínalíty nmlciple. min: typc lnstnncc. and thc class wine as thc nllnwrd class for its vaku-s. Domaln and range of a slot Allowcd clzssws for xlms nf typc Instunw un: oftcn atallrd u range o! " n slm, In thc cxumplc in Figurc 4 thc Clilsx r; m; ix thc nmgc of lhc p m . _u_- _ dm. Somc xyslcnu allow rcstricling thc mngc of a aki! whcn thc slol is uuachcd Íor a puniculur cIaLxs. 1%: clussux m which u slol is ailluchcd (ur u clnxscs whíuh prupcny u alol dcsuribcs, uic cuIh-d thc domnin n! " lhc slol. Thc "Híre s, class is thc dumuin u! " thc pnrcwiJce : slol. ln lhc systems whcrc wc atturl: slots ln classes. thc classes m which ihc slnt is attuchcd usuully consmulc thc dnmaín of (ha! slol. Thcrc ha no nccd ln spxífy thc domaín scparmcly. 111: haslü rulcs for dctcmxinínp 4 domam and a runpc of u slol arc símilar: Whc-n dcfíniny: u domuin ur a nm gcjbr a xlul. [ind thc mm! Aqcncn/ l ("IHAZKCI nr rian" Ihat nm be rexvpcrIii-clv thc dumuin ar the runigefor thc slnls . On thc nrhcr imud. dn un! (faji/ w a rlnmain ami range ihat is nwrfáx" " Soma: syslclllw jusl sgxcif; mluc lypc isit! ) a cLm insicud of xcquiríng . s apcciul sutcnycnl of innmmc l)pc slutx IO
  11. 11. general: all the classes ín the domain of a slor should be described by the slot and insrances ofall the classes ín the range of a slot should be porcmíaljíllcrs for the slot. Do no! choou an overiy gcntral cIass for nmge (La. ont would not min! Jo nyaka the mnge THING) bu: ont would wam m chuoxe a class Ihat we'll cover alljíllers Instead of listing all pnssihle suhclasscs of the w1 ne class for the range of the produces slot, jus! Iisl wine. A! the same (íme. we do not want io specify the mnge of the slol as THING-lhe ama gcncnll class in un onloloy. ln morc spccifíc tcrms: If a [isi ofclasses defíning a range or a domain of a slot includcs a class ami its subdass. removc thc subclass. lf thc mag: of thc sloc contnins both thc wine class and thc Red lune class. wc cnn mmovc the Red Nine from the range because i! does not add any new informatioo: The Red wtne is a subclms of w 1 ne and [hm-tort the slm range already implicilly includes i! as well as all other subcluscs of thc wine class. (f a lisl ofclasses de/ ining a range or a domain o] a slol conmins all subdasses of a class A. but na! the class A ítself, the range should coutain only thc class A and nor thc subdasxes. lnstcud of dcfming thc tanga of thc slut (o includc Red Wine. Whíte Wine. and Rose Wine (enumzraling aII the direc! suhclasses of Wi ne). m can limit the rang: lo the class n: ne itself. If a Iisr ofclaxscs defíuíng a rauge or a domain of a slol conmíns all bm a fcw subdasscs of a class A. consíder i] the class A would mafw a morc appropríarc mngt dejínitíon. ln systcms whcm mlaching a slot to a class is thc sem: as adding thc class to thc domnin of llv: slot. the snrnc rulcs apply Io sloi attachmenl: Ou thc onc hnnd, w: should lry to maki: il m gcncml as possible. On the odier hund. w: must ensure lhul cucli class to which we anzich the slol cm indeed have the propeny ma! the slut represenls. We cun uuach thc tannin level slut (o cuch of thc classes rcprcscnling mi wincs (c. g.. Bordeaux. Merlot. Eeaujolai s. cm). However. sincs all red wines heve the tannin-level pmpeny. wv should insiead anach ihe slol lo this morc general class of Red wj nes. Generalizing the domain of thc tann i n level sloc fmher (by uuachiug il to the Wíne class instant! ) would not be currecl since w do not use tnnnin leve! Io dcscribe whitc wincs for cxamplc. Stop 7. Croah Instanoes The Iast step is crealing individual instances of classes in the hierarchy. Defining an individual instancc of a class requims ( I) clmosing a class. (2) creating an individual instance of Ihat class. and (3) fulling in the slot vralues. For exanple, we can create an individual instance Cnatea u- Morqon-Beaujolais (o nemesen! a specifnc Iype of Beaujolais wine. Chateau-Morqon- Beau jolais is an inslnncc of thc class Beau jolais ttprcscnling nll Benujolnls wincs. 'I1|is instancc has the folkrwing slm valucs dcfincd (Figurc 5): 0 Body: Liglu 0 Color: Red 0 Flavor. Delicate 0 Tannin Ievcl: low 0 Grape: Gamay (instant oflhe Wi ne qrape class)
  12. 12. 0 Malter: ChIIcnu-Morgon (instnncc of the w: ne ty class) 0 Regina: Bcnnjolnis (inslnncc ofdrc Wine-Region class) 0 Sugan Dry Eaflmli-Ju Munquru Hr-nulnlnv. |IIi-.1u| u|,1un| Í-T | Beawoiw-own Ócnnnnuuomn [T É-oamwurapo Figura S. Tln dnllnluon olnn hinne: o! itt Innujolnin dz. Tln IIIIIIR ln chntnnun nagyon nnnnjolun mm the Iennjuinln reglon, prodnoed trnlntheGunny grnpe b: Ibe Címem Mntunuwinry. llhnuliglthdyddicnnflnvonrcdoolonnndlnwhnuhlnnthhndry winn. 4 Deilnlng classes and n class hlernrchy This secúon discusses things to look out for and errms ihat arc easy to min: when dcfining classes and a class hierarchy (Slep 4 Írom Section 3). As we have menlioned befon. (harc is no single conect clas hierarchy for any given domain. The hierarchy depends on the possible uses of the ontology. the leve] of the damil dm is necessary for the applicalion. personnl prcferences. and sometímes tequirenrents for compatíbility wilh (Illet models. Howvever. we discuss several guidelines to keep ín mind when developing a class Menrchy. After defining a considerable number of new classes. it "is helpful to stand back and check if the emetging hiemchy oonforrns to (hess guidelines. 4.1 Ensunngthntmchsnhiernrchylsconnct An "is-n" relnlion The class hietamhy repmsents an "is-a" triatlon: a class A is a subclanss of B if cvery insmnce of A is also am instanoe of B. For example. Chatdonnay is a subchss of White wí ne. Anolher wny to min]: of thc lnxonomíc rclntion is ns a "kinti-ni" mlntion: Chatdonnay is n kínd of white uíne. Ajetlinerisn kindofanaimrah. Ment is n kindoffood. A subclass of a class rcprcscnu a concept ihat is a "kínai of" thc conccp: ma: the supcrclass represcnts. A slngle wlne Is ml n Iuhclnsn ofnll nincs Aoounmnnmoddingunistnkeiswincludcbudnnsingularuidaplunl vctxionofdtcsum conccpt ín thc hicnmhy nullán; the farmer n subclnss of thc Inna. K): cxnmple. il is wtong lo definc I class Wines and n clus Wine as n subclnss ofhlines. Onoc you lhink of the hicnrchy 12
  13. 13. 3x mprcwming Ihc "kinő-ni" rclziiinnship, (h: mndrling crmr bcvnmrs chtur: u singlc ÍŐÍJ", is nm a kind u! " hímes, Thc bent wny to amid such gui crrur is nlwnys to usc cithcr xingular or pluml in nziming Clnswcs twcc SCÜÍOH 6 for Ihc ŐÍNCIJSNÍOH nn nnming CnnCCpIsI. Transitiirity of the hierarchiai! relations A subclátxs rclationship is minxiiivc: If B u a subdaxs" nfA and C is a xubrltux nf H. (hm C is a xubrlaszc nfxt For eiuimple. M- cnn deiine a": class '51 r'i i. und ihen defme u class m; ; L. w_:1a sas u subclam uf '. 'Jir, -;. Thcn n'a: dcfinc u class VI.13 zwizrir ' 4x u suhchm o! " Tinitu: u"; .- c. Tmnaitiwity uÍ thc subzluss FCIBIÍODShIP mcnns Ihat thc class rítt: a L r. ;'i. =_ v, IS alw a subcluss ni" 1 z: Somctimcs w: dislinguish Rtwccti dirrcl xuhclusscx und indirccl suhclusscx. A din-c! subclaas is lhc "Uluxtsi" subclaxs uf thc cluxs: lhcrc art no elemes bclwccn a class und Íls din-cl sutwlass in a hicrzurhy, "Hint is. thcic arc no otlicr classes ín thc hicmichy bctxu-cn u clam ami] its diwc! supeirluxx ln nur exaimple. *-, r'. "ial'_'f_ií_'u'li' . -_; is a din-cl suhclziss uf '. s't__-_ v v-irv: und ix mi! il dirccl subclnss o! " Ni ne. Evolution of a class hierarchy biziinmining a consislcnl class hicrzirchy nuiy twcnmc chzillcnging as dnmuinx cvnlw: For cxaimplc. for muny yczirs, zill Zinfnndvl wincx mire rcd. Thcrcfivrr. wc dclinc i: clusx of 7n= !._= .iir,1r_-l lVÍnCx as a Sllbüiálss of thc Pun! _ w, class. Snmctimcx. hnxvcvcr, winc mazkcrs bcgun m prcss thc grupcs und [u Iakc uwziy thc culur-gmxluaing AINPCCIN uf thc gralpus immcdiaitcLv. Ilicrcbgx nzodifying thc color of thc rcstilting wínc. Thus. sw gct "whiic Iinfaxulcl" u-Iynq- Cijilur is rme Now we HEH] m brcuk the : L."; ,7.i'11__ class imo twa) Ciklshrx of unfundcI-rlhite zinfszruje; und ideai zinfandiel-and cLusiÍy thcm JS subclasws of s í l e und püff! : 31'- rcspcctivcly. Classes and their nemes II is imypmtzanl 10 dislinguish bclvrccn u class und ils numc: ("fussa rvprcscnl cmuvpis ín thc (ÍONIIIÍH (NM! na: thc WlJ/ (IS ihat cieunrc thcsv cuncqvrs. Thc namc of a class ma)" changc if wc chuosc . i diffcrunt lcnnincilogy. but thc lenn itaclf rcprcscnls thc cvbjoclivc rculity in thc umirld. For cxamplc. m'c muy crrnlc u cLixs 5% r - 1x; und thcn rcnanxc it m P xu. e; n a-thc class uill rcprcxcntx thc samc uonccpt. zXppmpriatc winc cumbiiuitixms Ihat referred n) xhrinwp dixhes shnuld irfer m pruwn dishes. ln [HUN piaictiiuul terms, the favlliming mle shnuld silvaaiys tv followed: S )'Il0Il_YIn. í fnr Ilw mmc cmivepl dn unt rvjvrvscnl (Íijjcwc-nr chuyvx Synonyms arc jusl diITcrcnl nunx-s Íor a conccpl ur u lcrm. Thcmfoir. wc should nol huvc u class cullcd élt: irip and a ckm cullcd I= rawn. und. pussibly u cluss callcd Cr a: ;: : az. Rulhcr. thc-m is onc class. nanwd cithcr filzx m; or E'i-e un. hlany systcms ullow asxociatíng a list of sywixzviiyriix, lmnxlzilions. m [vresenlailion urunk-x with il class lf u sy slem does nm ullmv thew ÉINMKÍEIÍÍÚÍIN. synnmvms could zalxvaynx bv lislcd in thc class dnxcumcnlasliimi Avoiding class cyclcs Wc shnuld mwnid cyclt-s in lhr clam hicrurchy. Wc suy thut lhcrr is a cyclc ín u hicrarrhy whcn volna cluxs A hzix u suhclgiss B und ul thc mint limc B is a supcrclnss uf A. Cncaling xuch u ryclc in n hivrurchy amuunts lu dcclaxing lhul lhc L'Ius. scs A und B m: cqunulcixl: ull insumccs uf A am- inshmccs oí B mid all insluncus u! " B arc ulsu insuurccs of A. Indcud. sincc B is u subcluss of A. ad] BR inslamccx must be" ÍJINIdIKCN uf Ihc class A. Sincc A is u subcluss of B. zill A's inslunccs II
  14. 14. must also be inslanocs of thc class B. 4.2 Analyzíng síblings ín a class hierarchy Siblíngs ín a class hierarchy Slbllngs in lhe hierarchy m classes [hm arc direcl subclasses of the same class (sec Secüon 4.1). AH thc síblings ín the híerarchy (exceprjbr the onts at the ma! ) must be a! the same leve! afgeneralíty. For cximiplc. Hhite wine and Chardonnay should not be subclnsscs of thc sem: class (say, wine). Wliite wine is a morc general coneept than Chardonnay. Sihlings should nepneseu! concepts Ihat fal] "zajong the same Iine" in Ihe same way (ha! summa-leve! seclions iu a book arc a! the same leve! of gencraliiy. ln Ihal sense. requiremems for a class hierarchy arc similar no the requiremems for a book outline. Thc concepts al the mol of the hierzuchy however (which nm ottan represemed as direcl subclasses of sotne vvry general class. such as Thinq) mpmscnl major divisíons of (be domain and de not haw lu be similnr cunccpls. llow many Is too mnny and how few arc too few? Thcn: m'c no hard rulcs for thc numbcr of dircct subclasscs ma: a class should havc. Howevcr, many mlI-stmctmrd ontologics havi: betwccn two and a dozrn direcl suhclassc; Therefmt, w: hnvc thc following two guidclincs: Ifa class ha: only one- direct xubclass (here may be a modeling problem or thc onmlogyv ix m)! campicle. Ifthere arc morc llzan a dnzen subclaxsesfora giirn clam then udditicmal intenncdialc catcgories may be NCCCJSGT)". The tirst of the two rules is similar to a typesetting rule Ihat bulleicd Iists should nevet haw only one bullet point. For example. most of the red Burgundy wines ara Cbtes d'Or wines. Suppose we wamed IO represem only ihis majority type of Burgund): wines. We could cneale a class Red Burgundy and then n single subclnss Cctes d' O: (Figura 63). However. if in our mpttscntalion rcd Burgundy and Cótcs d'Or wincs arc csscntially cquivalcnt (nll rcd Burgundy wincs arc Cólcs d'Or wines and nll Cötcs d'Or wincs arc rcd Butgundy urincs). creating the Cotes d' O: class is not ncccssaxy and docs not add uny ncw infommion lo thc rtprcxnlnlion. [f we were m include Cótes (Íhalonnaise wines. which art cheaper Burgundy wines from the rcginn just South of (Tincs d'Or. then we xvill create twn suhclmscs of the Burqundy class: CoLes d' O: and Cotes Chalonnaise (Figure 613). 9 Ó Red wm 9 Ó Red wine Ó Beoulolais Ó Bcautolals 9 Ó R. ed Burgund; 9 O Red augunuy Cotes d'Or Cotss mor 9 Red Zintandol Cotes Chalonnanse _ 9 Red Zmfanoel Figura 6. Subcluwes o! the Rad Buxqundy class. Havlng a xíngle subcluss o! a class usuully poinls h a pcohlem ln nodelhg. Suppnsc mw ihat we Iisl all types of wines as direct suhclasses of the Hine class. This Iist would then include such mone gcncrnl lypes 04' wine as Beaujolais and Bordeaux. M well as mone specific typcs such as Paulliac and Margaux (Figure ón). The class wi ne has loo meny dinecl I4
  15. 15. subclasses and. indeed. for the omology to reflect nhe different types of wine in a morc ommized manner. Medoc should be a stabclass of Bordeaux and Cotes d' or should be a subclass of Burgundy. Also having such intermediale calcgories as Red wi ne and m1 íte wi ne would nlso rcflcct thc conccptua] nmdcl of thc domain of urincs Ihat many peaplc hava (Figura ób). Howevcr. if no nalurul classes cxisx to group conccpts in thc Iong Iist of siblings, therc is no noed m cmnc milícia! cInsscs-just Icavc thc classes thc wny lhcy arc. Aftcr all. thc ontology is a rcflection o! the rcnl world. und if no cmlcgorization cxists in thc real world, lhcn thc ontology should mllcct thnl. f . W1ne f Owine 9 O whls wine O wmg van; 9 Ó Whil! Buraunov Ó Rose Mm Ö Chabls O Red vme Ó PouIry-Fursse Ówhite Burgund; Ó Chardonnav O Cnonin Blanc Ó chonin Blanc C Charoonnav O Punoc alant O Pinot Blanc Ó Sauvignon Btanc O Samignon Blanc Ó Semmon Olce wane ? O Rieslno Owm Zlntande! Ó Dw Rtesllnu O Bewjolais . Sweet Reislng . Red Burguncy O sauleme O Red Zlnfando! O Whls soromat O Paulllac O Ice wIne O Margaux 9 O Red vnne O St Emilian O Beawolas O Grms 9 O Red Borounov O Red Bordeaux Ó Cotos d'Or O Sauteme O Cotes Chalonnarse Ó Cabemat Franc Ó Red Zinfmüe! O cabomet Samlgmn ' T 9 O Red Bordeaux C Nedoc 9 O Medoc O semllon O Paullac O Pina! Noi O Maruaux C chlum Ó s: Emnlon _ O Pem smn Ö Ocms O Sancene O Cahemet Franc O Iluscadel O ennem Samignon O Port O Plnot Nolr C amit Ronslng _ g gnuggu O Chablis Ó Dry Riasling Figura 7. Caeegorlzlu wlnes. Haha all the uhu and type o! wlne venne Imi; sem-u! levek o! caltgorinüon. 4.3 Miltipla inharitanoo Most knmvledge-mpmsemalion systems allow multiple lnherltancc in the class hierarchy: a class can be a subclass of sewra] classes. Suppose we would like to cneate a separate class of
  16. 16. dcssen wines. the Dessert w; nv_- class. Thc Port winc is boch a red wine and a (lessen winef Dmefotvc. m: dclim a class Port Io harc lwo supcvclzwscs: Red wine and Dessert wine. All instances of thc Port. class will be instnnccs of both thc Red wLne class and the Dessert. uLne class. The Port. olasz will inherit its slots and thcir faccts fmm hoth its pamnls. Thus. íl wiII inheril thc value SWEET for (be slol Suqar Írom the Dessert wine class und thc tannin level slot and thc vnluc for its color slol Írom thc Red wíne clmas. 4.4 What: m intmdueo a now class (o! not) One of the hardest decisions to make cluring modeling is when to introduce a new class or when m nepnesem a distinction Ihmugh different pnopeny values. lt is hard IO navigate both an cxtrcmely nested hicrarchy with many extranccuxs classes and a very fiak hicrarchy ihat has ím few classes wilh too much informalion encoded in elme. Fmding the aqumpriane halance xhough is not easy. Duett arc scvcral rulcs of thumb that help dccidc whcn (o íntroducc ncw classes in a hícmrchy. Subclzisxes of a class uxuallv (I ) hava addilional propcrriex Ihat the superdass dnes na! haw. or (2) restrícrinns ditferentfrom thoxe of the superclass. or (3) parlicipate ín díjferem relationships than the superclasses Red wines can have differenl levcls of (manin. whemas Ihis propeny is not used lo describe wines ín general. The value for the sugm slol of the Dessert wine is SWEET. whcmas it is nol (ne of the superclass of the Dessen Winc class. Pinol Noír wincs may go well with seafood whcreas other red svines de not. ln olher tvords. w inlroduce a new class in the hierarchy usually only when there is somelhing thal we cal: say aboul this class Ihat we cnnnot say aboul the wperclass. ln pmciical (enns, each subclass should eittier have new slots added to it. or hava new slot values defined. or override some facets for the inhedted slots. Howcver. somelimes i! may be useful to cneanc new classes even if lhey do not introduce any new propenies. C lassex ín termiualogical hierarchia do na! hava m intmduce new pmperries For cxample. somo: onlologies include Iargc referencia hierarchia; of common lcrms uscd ín the domaim For example. an onlology undedying un elecuonic nwdical-tecord syuem may includc a classiíication of various diseases. This classilicalion may be jusl Ihat-a hieramhy of terms, widiout propcnies (or wilh the same set of propmies). ln thal case. it is still useful to organizc the terms in a hierarchy ralher [hám a flat list bomuse it xvill (l) allow easier exploration and navigation and (2) enable a donor to choose easily a Ievel of genemlity of the tetm ihat is appropriale for the simation. Anoiher reason to introduce new classes wiIhouI any new propeníes is m model concepts among which domain experts commonly Imke a dislinction even though we may hava decided non lo model the distinction itself. Since we use mtologies to faciliuue communication among domain experts and benvccn dnnmin expens and kmwledge-hased syslems m wvould like m retlect thc experfs view of the domain in the ontology. Fínally. wc shnuld not create subclasses of a class for each additional rtstiiction. For examplc. wc introduccd thc classes Red wine. white wine. and Rose uine bccausc lhis disiinclion is a natural one in the wine wmld. We did not inuoduce classes fot delicaie wine. ' W: elme: io mpmscnl only md Pacis in our omology: Miit: Pons do enist hm lhcy u! extrcmcly unoommon. |6
  17. 17. modcrale winc. and so on. Whcn defming a class hieranchy. out goal is Io strike a balance bemeen cneating new classes usefu! for class ooganization and crealing Ion many classes. 4.5 A nem class or a property valuo? When modeling a domain. we ohen need to decíde whethcr lo model a specific distinction (such as white. reá, or msé wine) as a property value or as a se! of classes again depends on the scope of the domain and the task at hand. Do wc cmalc a class whate ui ne or do wc simply crcalc n class Wine and I'll] in diffcrcm vatues for the slot color? The answer usually Iie-s in Ihe scope Ihat we detined for the omology. How impuruml thc conccpt of Wnite wíne is in om domnin? II wincs havc only marginal importanc: in the domain and whelhcr or nm the wine is white does not hava any panicular implicaliom for ils rclaninns m othcr crhjccm, thcn wc shouldn"! introducc a scpnratc class for whilc wíncs. For a domain modcl und in a facmry producing wínc Iabcls, rulcs for wínc Iabcls of any color arc thc samc and thc distinctíon is nm vcty imponam. Altcmalivcly, for thc rcptrscnlaliou of winc, fond. and thcir appropdau: cotnbinatious a ncd win: is vcry diffcrcnl Írom n whitc winc: it is pairtd with diffcmm foods. has diITcttm propcnics. und so on. Similnrly. color of winc is importunk for nhc wincs knowlodgc has: Ihat wc muy usc to dcxcrminc winc-tusüng ordcr. Thus. w: crcutc a scpurmc class for rJh i te wí ne. lfthe concepts WÍIÍI dtferent xlat values becnme rcxtrictirms far dtferent slots ín other classes. then we should rreatc a new class for thc distinction. Othersvise. wc rcprcscm the distinaion ín a sloc mlue. Similarly. out wine omology has such classes as Red Merlot and Whíte Merlot. ralher Ihan a singlc class for nll Mcrlot wincs: rad Mcrlots and whit: Mcríots arc mally diffcrcm wincs (nmdc írom thc same grapc) and if w: arc dcvelopíng a dctailod ontology of winc. dús distinction is imporlant. Ifa dístincrion is impormnt ín the domain and we Ihink afthe ohiects with dxjfereru valuesfor the dixtinction ax drffercnl kinds ojolzieclx. lhen w: shauld creare a nzw classfor the distinctioru. Consideting potentíal individual instanoes of a class may also be helpful in deciding whether or not m intmduoe a new class. A clms m wlrich an indi vidual instanre belrmgs should na! rhange often. Usually when m: use cminsic rather Ihan intrinsic propenies of concepts IO differcntiale among classes. inslances of those classes will have Io migrale ellen from one class to amther. For example. Chi l 1 ed mi ne should no! be a class in an onmlogy descdbing wine boules in a restaurant. The propcny chilled should simply be an auribule of winc ín a boulc since m1 inslancc of Chil led wi ne can cnsily ccasc being un instnncc 04' lhis class and lhcn bccomc un instance of lhis class again. Usually numhers. colon. locations arc slo! values and ón nm cause the creation of new classes. Wine, howewr, is a notahle cxccpamn since the colnr o! " the wine is so pammounl m thc dcscription of winc. For anoiher cxamplc. consider the human-anatnmy ontology. When wc repítsen! rihs. do we crcatc a class fot cach o! " thc "l" lcft rib". "2"' lcfl rih". and so on? Or do wc havc a class Rib wíth sIoIs for thc order and m: Imcral pmilíon (lch-rigluws If u: infonnation aboul cach of thc rihs ihat we rcprcsem ín the ontology is signilicantly- dilTcrenl, lhen w: should indccd erem a 5 Here w: assume that each ananocnicnl organ is a class sínre ne manld also lik: to tall; about "John's l" left rib. " Individunl otgnns of cxisling pwplc would bc rtprcsmvd as iMivídunls ín our omology. |7
  18. 18. cluxs for cuch ni lhc rihx. "Thal is. if wc mint Io rcprcsvsnt dcluils udjuccncy and Incuiinn infnrmulion Iwhich is diffcrcnl for sas-ch rib) m wcll ílx spcClrlC functinns ihat cach rib plnyu zmd orguns i! prolccls, m: mm! thc Clusws. If m: arc modcliuig unalnmy m a slightl_x* Icwsr lcvcl of gcncmlity. und zlll rihs arc wtry ximilur us far as uur pntcllllill npplicfilinlls arc cnnccrncd (wc just talk ahoux which rih is hmkcn nn thc X-Ray uwithoul implicalicms Inr mhcr purts o! thc hndyb. wc may wam m simplii"_x' our hicmrchy and huvc Jusl thc class -it. a. with lwo slots: l. *."*f1l )""Ü.1i'. _*'. ['.1'*I! .l, I. 4.6 An lnstance or a class? Dcciding whcthcr a puniculnr conccpt IS a class. m un ontolug_x- or un indiwidual insumcc dcpcnds on whul lhc px-mtcntiul dppllCilllUllS uf thc (nnlulngy ama. Dccíding whcrr: classes cnd und individual ínskmccs hcgin slunx wilh dcciding whul is lhc Inwesl Icvcl uf grunulurily ín lhc Nprcsciiluliuri. l'in- lcvcl uÍ grunuluril_x' ix in lum dclcnnincd by n pulcnliul npplicalian o! " thc onmlnwgjxu ln avlhcr uurds. wlml urc lhc uiosl apccilíc ilcnxs [hal un; going ln ty rcprcscxilcd ín thc knuwlcdgc hasas? Going huck no (h: COIIIp-Jlclk") quthliuílx wa: idcnliűcd in Slcp l in Scclion 3. thc rum! s; wific cuncupls lhul will cunslilulc unswcrs lu (hun: qucxlirvns alt vcry gumi cundídnlus fur intlisidixails in thc knoulcdgc hehe. Individucv/ instancia; arc rhv mm! spcujic (nnvvpls reprvswzlcvr/ ín a Á'Iltru'I('d_q(' bujt For cumplc. if wc arc only going to uilk nboul painng wmc wnh food wc wiII not bc Inlcrcslcd in thc spccific physiuil boülcs uf winc. Thcrcfuru. such lcrms 45 '; 'te"l ' n; i negxsnd; "ne: 1 a w' arc probuhly pninp to bc thc most spccific lcrms wc usc. ln mhcr uwnrds, thc Winc class Íx a! colleclirsn na: of individuzil [Nllllex nf wines hm nuher 01' the speciűc wincx gumimmal hy speciíic wineries, Therefcsre. 15', u; L- "l j '*. "_r a: 2.1 n: 11-; m: wuuld be un inslzmce in the knuwlc-dge husc, On thc olhcr hunt], il" wc wuultl Iikc ln muinlain un invcnuury uf winca ín | hc restaurant in aiddilítm lu lhu knmrlcdgc buw vf guud winc-Ítvnxl pnirings. individuu] boulcx uf cucli winc muy bccunz: individunl inslutlccs ín uur knmwlcdgc busa, Simihurly. íf we wuuld Iikr m rrvnrú diffeiuuit pmpenies far cucli speciflc irinnnge of the - ' :1= , , thc-n thc speciflr rinmge ni" thc uine is un Ílhlillltfe ín u í rag i rágd r , ; mer ' g: ix a class cunluming inslanccs for ull 97, : l-7u. '; '*. '1.'IL'J'= Í knowlcdgc tust and ' ils vinlugncs. Anothcr rulc can "mmc" mmc individual inxtunccs imo thc sct of classes: Ifrunrepr: jbmt a Hamm! hicrurclrv. Ihcn wr- shuuhl rcprcxcnl lhcm a; rlnrxcts Cansidvr Ihc winc rcginns lnilizally, wc muy cicíínc main svinc rcginns. xuch as Franco. LTnilcd Slsncs, Gcmwny. und sn mi. Áh clamex und xpstciiic winc rrgions wilhin thcw Iznrgx" rcgionx us inslanccs, For cxzunplc, l'w', |_JY'1,_ qu , rg u; u is an inxlzmcc nf lhc IA r : ny! r, v; w- claxs. llowcvcr. wc wuuld uhu lika" Io suy lhul thc Sicc: w: *I"ZÍ** vej? üll is u -1r: v.1"wr]w; *.r_? r'ie xegiwzm. 'I'hcrciorc. 11.4 í-güv gne [n-HIJJAÍJI. must be n class (m ordcr m huvc SübClnSScx nr insmnccs). Howcvcr. Imiking í: wur ny grav- m: , wvn u class und r" ni p; .; ' t? v-w l an inslzuicc uf E-cu; rcxcwgrte regicvrl xcclns urbiuurw: il is wiy hurd lo clcurly dislinguish which rcgiom arc classes und which arc insxunccs. Thcrcíorc. wc dcfmc ull winc rcgions as classes. Prulégó-MKK) allows uscrs lu xpculy somc classcx as Abslrucl. xignifywng thul thc class cunnut hnvc nny dirvcl inslunccs. ln out cusc. all rcgiun classes arc uhslracl (Figurc 8). IS
  19. 19. 9 Ö Wine radon 5 O United Stalas region* 0- Italian rsgion 4 9 French region* 8 Alsace iegion 5 Beauiolais rogion 5 9 O Bordeaux rsoioM Ó Mamut reoIocM Ó Paullac reoion 5 Ó saunrno romon 4 Ó s! Emllbon mgIorM 9 I BDIIIIM MIN O Colos d'Or reglon* Ó Moursaun regIonA Ó Coias cnalonnaise roglon* 0- . Loire rooion* 0- ' Australian roglon* Figura I. Blerardiy of wlne nglons. Ti: "A" komi non lo uhu nana hinne tini the classes arc Ibstrnu and unna! Int uy diroct ilsunas. Thc same class hicrarchy would be incmcct if wc omined thc word Wcginn" fmm thc class nnmcs. Wc cannot sny dm thc class Alsace is n subclass of thc class Franca: Alsacc is not a kind of France. However. Alsace region is a kind of a French regjon. Only classes can be amnged in a hierarchy-krmwIedge-ivepresenxation systems do not have a notinn of sub-inslance. Therefore, if there is a natural hieraichy among terms. such as in terminological hierarchies from Sectim 4,2. we should defme these terms as classes even though they may nm hava any instances of their ovm. 4.7 Llmmng thc soopo As a final nmc on delíning a class hierarchy, the following se! ni" rules is always helpful in deciding when un mtnlogy delinition is complete: The ontolagy xhauld na: conlain all the passible injivmnarion abaul the danuiin: ywm do not uecd m spccialize (or generalize) morc (hari wu nced for mar application (a! most ane ami leve! each way). For 001" wine and food example. we do no! need IO know whal paper is used for the Iabels or how (o oook shiímp dishes. Similarly. The ontology should not conlain alI thc possible properties of and distinctions among classcx ín the hierarchy. ln our ontology. we ccnuinly do not includc all the propmics ihat a winc or food could hava. Wc represciucd thc mos! salient propertics of the classes of itcms in our onlology. Evcn ihough wine boults would lcll us the sin of grupcs, wc huvc mi includod Ihis knowlodgc. Similarly. wc hiwe not added all relalionships (hm one could imngine among ull the team in our syslem For exumple. we Llu no! include Nlznionships such as favorite wine and favoríte food in thc onlology just to nllow a morc complclc irptcscmation of nll of the inni-connecticuti; bctwccn thc lmns w: hnvc delined. Thc lnsl rule also applics lo cslablishiog ttliuions among conccpts Lhnl w: havc nlrtady included ín thc ontology. Consider un ontology dcscribiug biology expctimmts. Thc onlology will Iikcly conlain a conocpc of Biologícal organisms. I! will iilso conuiin a cuncepl o! un |9
  20. 20. Exí-uí _n n: : _ pcrfrurníing un cxpcrinvcííl mith his nunvc. uflilmrinwn. Cm), l! is Irur than zin uxpcrííiícíilcr. as. .i [v-císutí. ulw huppuns lu bc a blUlUglClll ivrganisxíi. lluncvur. wu prubalvbi should nul inuuípiírulc lhís dislinclixírl ín thc unlulngy: fut thc purpuscs uf lhís IVPFCNCNLIIÍGÍI dll cxpcritxtcíllcr is nut u bíulnrgíuíl (vrgzmisílí und xw will pnububly ncwr CUIIÚLICI uxpcrítíícnls un thc cxpciiníciílcís rlwcmsclvcs If wc nem rcprcsmítiííg cvcrsíthiiíg ne nm sny ulsnut Ilic i-Insscs in thc untnliigy, un Ez-z; ;: xugni z, 1 suiuld Nuunc az suli-class (if Én , 1.11- A É: í íítíatn. lluivcvcr. w: dn nul nrcd ln ínclíídc lhís knmwlalgc Ím thc lvrvsccublc applícaíliivns. ln luci. ínuludíng lhis lypc uí uddíunvíníl uldssíficulitíí) for eíusling claisscs . n'luull_x* hurts: nuw un ínsluíícc uf un lixpcrinzcíílcr wíl] huw slnls Ilrr ucíglíl. ugr. sprvies. und ollícr dulu p-cmíjíííríg 10 u híulugical uígunísm. bul uhsululclv írrclcvmíl ín thc csmlcxl uf dcsunhiíig un cxpcrímrríl. llnvwcvcr. wc shuuld rcuurd suclí dcsigíi dcuisiivíi ín thc ducutrícrílulíuíi fur ihc bcncfil uf lhc usus uhu uíll bc lovkíríg ul lhis l| lll0ll*l__-'_N' and uhu nmy nul hí: uwairc u! " llic üpfllltulíull uc had ín mind. Ozlwcrxwisc. pcvplc inlcnding ln rcusu thc tmlnkig) for níhcr Applicaííííníis nmy lry ln usc cxíwcriíizcíilur aís u sutwluss uf pcrsivn WÍIIIUUI knnsxing lhul thc urigiíiaíl nuidclíng did nní inclíídc ihat félti. 4.8 Disjoint subclasses huny sysltllh nlluw u. s 10 spccily c. xplícíll_s' llml scveral classes an- dlbjlbllll. Classcs arc dísjuííil í! " lhcy (anno! hnvc un) inslmíccs ín cumnínn. Fm cmuízíílu. thc Le ' ; a r: 24; 71-2 und thc '. '.": . i te Siítu clusscs m our onmloyy arc nm dísjoint: thcrc arc muny wmcs ihat arc instnnccs of bnth. "ni: Füííw-rív-í T: I'Il"*íII'l. :' l".1|, .*§l"'. .: Íl". ' ni: insmncc Uf thc Fia 51; n: class is unc such (Xilíllplt. A! thc saníc liníc. lhc 3-, ,. ne und thc Cal: ; _ e z-vi ne cLisscs un- dísjním: no wínc Cllfl be símulmnctvusly rcd and vrhííc. SpccíLving lhnt classes ima dísjoml cnublcs thc systcm lu suhdulc (h: untulugy bcllcr. [Í wc dcclm thc uie: z-zi ne und thc Éíw 1 : v, l m; Ulusscs m be ilisjxiiíit ami Inícr crcurc a": class Ihat í. s u NIIlTCIIIxN nfhnth á: 1 1 í'-' (u NlIhClilNN uf 22' u: r wir "i and F u: Í (ü sulwlass uf 3'. i 1 IZIJ l. u syslclíi van inalículx" thdl ihcrc is a nuvdcling: emír, 5 Deílnlng propertíes-more detalls ln Ihis NLYCIÍDI] uc tlísítllss scvcrul morc dCLIÍís m h-cp ín mind whcn dclining slms ín thc tvmnlngy (Slcp 5 und Stop (u ín Scciiníí 3). lvíuinly. wc diwiíss inwrv: slms und ilosfzínlí vzilucs for a sínt. 5. 1 lnverse slots A valuc ni" a slm Inuy xicpcml on a vuluc cifzmnthcr sloí. kor cx-unrplc. ifa x l r-g inas í r m, . b; - u '. -.'1rí: :;. =. lhrn thc 1:ir; :;. ' jECElUCFF lhul WlÍlF llícsc lwo rclaníuns. ím ÍPL" und ; v:: rlIí. 'v'-5. arc: cnllcci inverse relnlínns. Stcring thc inltxrmaliíin "ín hníh dircclmns" is Ieilíínalsuíí. When we kmm íhnl zí winr is pnxlucvd by u wineiy. un npplículicníí using the klíuwleilge has? van zulsxzqs infeí íhe vnlííe fen lhr inwrsc- reliniuvíí íhul lhe min-sí) pmíluces the nini: Hcixwxcr. frum thc krimiIcdgcantqiíisiliíxn pcrspx-cíixr i! is vnnvrííicííí m huw holh piurvs nf ínfnmuniíríi cxplírílly uwuiluhlc. This uppmuch allnws uscrs ín Iil] in lhvc winc in onr cusc und thc wíncry ín annlhcr Thc lxnüvrllfdgfxlüllllísllílín syslcííí Címld íhcn Ziültmlálllcállly fill ín íhc níluc fnr thc inrcrsc FCIJIÍOI] insuring cnnsistcxncy ni" ihc LmwaIcdg-s hass. Onr cumplc hns a": pnir ni invcrsc slnts: íhv r í. ;,l' u, r slnl nf thc r; í Clziss und thc y - u : ,. _ _ sIiH uf lhc r. ' "i: "u" class. Whcn a uscr titulus un insuincu uf (h; ' e class dlltl lills ín thc vuluc m: thc miuut-r slul. thc sysicm uutoníalícally ndds thc ncwly" crcalcd insluncc to thc 20
  21. 21. p: .. MÍLJ slm nf Ihc crurrcxpuwnniing H; m. 1 y instmwc, Fnr insmncc, uhcn m: xny Ihul Slcrling kin-rím ix pruducud by thc Slcrlilng Vinryurd uiurcry; lhu xyxlcm wuuld aulunlulicully add Sluling hícrhn m thc m uf wincs (ha! lho: Sterling Vincgwaurd winv: r_x' pruduccx. (Figurc 9). 1 smmmmmm -I: IxI f * S1er| '19 Nem o! [Éraáijnfr Év, |-'t,13', "r. _ n x í "' I Sterlunu; Vm ewards x . Sterl '19 küneyards "'*/ í _ V c; + _ I uíFzLoTuwupu I Napa H V CÍ + - TPIIIH; r-"r-rlc? 8,, m c: Charcannyr St-z-Ilin g Cabemel Samxgnaru Figurt 9. Inslanccs vrílh invcrsc slots. Thc slol produces for thc class Wmery is an invcrsc of thc alul malter for the class Kinn. Fllllng ln om- nf llu: slols trlggurs un uulumatíc updatn: u! the ulhur. 5.2 Delaun values higany fmnIv-buacd syslcxux ulluw spccificulitun uf (lehull valurs for xlols, lf u [JRHÍÍUULII slul vuluc 1x lhc NJÍÍK for must inxlnnccs of u class. wc van dcfinc lhis xaluc lu be n dcfaull mim: for thc slut. Thcn. whcn cach ncw inxlnncc of u class cnmaining lhis alul íx crculcd. thc xyslcm fnlls ín lhc dcíuult vulu: uulnmeuicnlly. WC cun thcn chungc thc vuluc ln any mhcr vuluc lhal thc Iínrcls will ulluw. "Fhul íx, (lcfuull mlucs un. - lhcrc fur cumenlcncc: lhcy du nul cnforcc uny ncw ruslriclinvrlx un lhc mmlul m chzmgc thc uradul ín amy way. For CKHIIÍIJÍC. iÍ thc nmjurily uf urincx wc am- gmng lu discuax arc fulI-bxvdicd wíncs. wc L'un hgwc "full" m u dcfuull vuluc for (h; b4.vd_x* uf thc winc. Thcn. unlcm wc suy ulhcmíxc. ull wincx uc drüne wnuld be full hudied. Nnlc lhul lhis is diffcrcnl Írom 510! valuta. Slul unlucs umntvl be clmngcd. Far cxnnlplc. w: L'un xuy thul thc slnl s _ 3.511; has mlur SNVIEIIT fut thc De z z e n, v. ne cluxs, Thcn uII thc sutvclusscs and insmnccs of m: Les arat w -ne clasx wlll hm": thc SNVEEI" valuc for (h: xlm . .= r; _. L . Thix Hlluc nmnm be chamgcd in uny nf (h: xukx*| asscx or inxlannrcs nf Ihc class. , . 6 What s In a name? Dctiníng nnming cnnvcnticwns for uünccpts ín an nntülngy und thcn xtrictly aulhcring m lhcsc convcntixmns nm only mukcx thc cmmlngy cnsicr m unmlcrxtunnl hut ulm hclpx uvnid snmc cnmmmu Inndcling mislukcs. Thcrc arc Inany ullcmalivcs in nnming conccpls. (Jllm (hon: is m) paruculur rcuson ln chmwz nnc nr unnthcr ultcrnalix-c. Howcvcr. wc nccd m
  22. 22. Drjínr a Imming rnnvrvztinrz fnr rlnxsc-xv ami xlnrx ami adhrre ln it. "Ih- Ínlltnning fenmnex uf u knnwvlealgc teprewuululixvn syslcm affecl the chuice nf nanning xfltllvelllimlx. 0 Dócs lhc syslcm hnvc thc umc nanmc spucc Ibr cluxucs. xlms. and mstancc§f Thal is, dncs thc syxtcm allow havinp a class and a slm uwíth thc samc namc (such as u class ; r c-v ' und a: slnt van, 130" ' Is the xystem cvaxedscnsitiwrf? Thut is. dues the systenn nem the Hunt-cs ihat differ (unly in cm: ux difikre! !! nznnes (such ils h; m r und z-u nv z jl? 0 Whul dclimilc-ux deJcs thc syslxrm ullnw in thc narancs? Thul is. van numcx crunlnin sgxuccs. Cümnlih. ustcrixks. und sO nn". Pmté-gílfi-DO, far cxzunplc, nlaxinlains a sin-glc numc xpzncc for all ilx frulncs. II is nxuscvscnsilixux Thus, wc czmnm hzwc a claxs v: w. ' und a slnt v: m)! v, Wc cam. howcvcr, hun: h class Vary (nulu lhc uppcI'-('; |su) and a sIul m rery. CLASSIC. un thc uthcr hund. is nul num- scnsitivc and maimuins dnffcrcnt mm: spaccs for classes. slots, und indixuduuls. Thus. fmm a systcm pcrspccxivc. Ihcrc is no pruhlcm m nuuung b-mh a class and a slot r: L ne ty. 6. 1 Capitalization and delimíters Fim. wc czm gnfull) Ílhpmvof lhc rczndzibilily ofun nmmngy if wc uwc consislcnl cnpíuaIi/ utinn for cnncrpl nznmcx, For cxamplc. i! ix cnmmnn m cznpilulln: cluxs numcs and un: Iowcr cusc far slnl nauncs (assumíng thc xyslcm is Caisc-xcnsilivc). Whcn a conccpt namc cnnlains morc tham nm: wnrd isuch us r-íeau 1 Ti? u ne) m: nccd ln dclimi! thc wunls. Here zur wmc pussihlr chuiucx 0 llsc Spucc: mm tan w (muny xystcms. including; Prmégé, nllov. spaccs in conccpt nzunes) 0 Run lhc wurds tngclhcr and capilalizc cauh ncw word: Ha": 1 ("1111 r 0 lixc an undcrxcturc or dash nr (wlhcr dclinlilcr m thc namc: P*Ír'-"11_IÍÍ.31.r: I-1u- n- I; :.: _. Ti; IHÍJULHLH; _ -A_'w, '.11': -; (If you lIsC dclinlilurs. yuu will aIIsu nccd lv dccidc whclhcr ur nm cuch ncw uurd is cupilulixcd) IÍ thc knuwIcdgc-mprcxcnmtion syslcm ullows xpaccs m numcs. using thcm muy be thc mos! ínluilixc sululíon for nmny tmlultvgy dcvclopcrs. [l is huwcvcr. impununl lo conxidcr olhcr xyslcnns wilh uwhich yuur xyslcln muy mlcrucl. If lhusc xysicnns du not usc spuccs or ií your prcxenlatícvn mcdmm duvts nm hundle spamcs wcll. il cun be uscful lu usc annlhcr mclhud. 6.2 Slngular or plural A class nana: reprcscnls u LUHCCIÍOH of crhjccls. For cxutnplc. a class Hi n; udually rcprtscnls all wincs. Thcrcforc. it could h: morc nmurul for mm: dcsigncrs to cal] thc class h" i (HÉ-F. mthcr thznn r. r , . Nn allcrnaslivc is Ntlcr nr wvorw lhsm thc nthcr (allhnugh singulznr for class nantcx is uwd morc uflct) in pracliccji. Ilowuvm. whulcxur thc choicr. il xhuuld be cunsisicuul lhroughotn! thc whnlc (mlulugy. Som-c s) xlctns cvcun rcquim lhcit uscu lu duclurc ín gndvuncc whclhcl ur nm thcy un" guing m uw singtnlur or plum] fut cunccpt hamus und do not ullow lhcm w struy fmm Ihat clmirc. [Ring thc san-c furm uII ihc tinu- alku prcvmts a dcxigrvcr fmm nmking such unmlcling mixtnkcs as crenting n clsm h'_ m, -. amd Ihen Urenlirlg u clzm 'ri'_r" us its Suhclilxs (sec Secticwn 4. I ) IJ 'sI
  23. 23. 6.3 Prefix and suffix conventions Snmc Lnowlcxigc-basc nwthuxlnulrrgics suggcsl uxing prclíx und xuffnx CDIWLÍIIIÍDIIS in thc nanwcs m distingunixh bczmsgwn Clíhscs und xInls. Twn cnmnmn prucliccs un: ln add u -u. _-, ._; 7 ur a suflíx a; lu xlul mancs. Thus. uur sluls hcüvmc ÍN 7 fala; r and I'm í. winery il- wc chusc lhr ':1 convcnucxn. Th: xluls bccomc imíae: :i ami n, mi 11' wc chusc lhc af convcnlion. Tíuis upprcmch allnuux unyonc Innkíng u! .n tcrm m dctcnuinc iunnvcdiutcly if lhc tcrm is a cLm nr a slm, Huwcvcr, thc tcrm nnmcx bccnnu: slightly Iongcr. 6.4 Other naming considerations HON: arc a fcw morc thingx m Cnllxidcr uhcn dcűning mxming cnnvcntians: 0 Do not add smngs such 1x "class". "pmpcny". "slot". und sn un tn conccpt nnmcx. ll is ulwuyxs" clcur furm | hc contcxl whclhcr thc conccpt u a class or 4 slot. for cxumplc. ln addiliun is yuu uxc díITL-rcnl nummg conwnuons for clnsscx und slnts huy. capiluli/ ulitvn und no mpiluh/ nliunr rcxpcclíx'cl_x* ). thc: nmrzc ílsclf uould be mdlculíxc oÍ uhu! lhu: nmnccp! is. - II is usuully u gumi idea ln amid uhhrevialiuns in cnuurept nuntcx uhut is. uw Í . t,w _ r" N _ i j n : n rulhcr (hun vaku) 0 Namsx o! dirccl sutxlmscs oÍ n class should cithcr nll mcludc m not mcludc thc nunu: o! " lha: supcrcluss. Fut cxumplc. ií wc arc crcunng lwu subCIusScs of thc w n: cLm lo rcprcxcnt rcd und whixc wincx. thc lwn suhclaw numcs shnuld be: cnthcr m1 az": m: and zinur Iiillv ur Év, r. und 221 , _ hal not F. _ u. í-Jlrxu; ami E(r, -: 7 Other Resources Wc hzm: ustd Pn'nc'gó-2(l00 m . 'm (unmluwgynicxclnplng cmimmucnl far nur cxamplcs. Dunincwrclxi ami Collcugllcx (Duincwcld cl al. 2000) elem-nm and counpurc u numhsr nf nthcr unmlogy- cicwlxspnxvcnl rnvircvnunvrnts, We hane uied ln zuldress Ihr sery hnivs (nf unluhrgy (Irwlupnverxt und hnw nm diwuxsed numy nf thc asklhllltifd Iupícx ur allcmulixc mclllrndnulcsgioss I'm csmulcxgy ckwxluwpntacnl Gúntsz-Pórcz (Gómcz-Pércr | *)')8V) und [Xchnhi (Uschold and Gruningcr IOOÓ) pFCNChl ultcrnznixwc amaulngyádcs'clnprl1osnl mclhcvdxwlcígics Thu Onlnlinguu lulnml (Fnrquhar I997) dixctxsscs santc fvnnul umccls uÍ knnwludgc Imvdcling. Currmlly; Itsuutllüs cmphusizc not vnly unlulugy (Iuwltlpnllrlll. bul alsu umulog) anulyxís. As muru cmlulugics unt gcncralcd and rctuwd. murc umls will lw uvailulwlc ln mmlyzu tvnmltsgícx, For cxautuplc. Chimucrax (MCCuinncxx cl Hl. 2000) prmidcx diugrmslix" lwls fUY anuly/ ing cmnlulxwglca. Thc unulyxia Ihat Chunucrzn gmrfvnns imludcs hmh a chcck for Iugicaxl cum-clncss vf zm tanlnltvgy und diugnmlicx uf wumnuvn muulng_v-d: sigI1 crrurs An vnlulugdv duxigtaur ma) waml Iu run Chimuuru dmgnnvslics uvcr thc cvulvixlg unlolavg_x* Iu dclcnninc lhc cnnfnnuaun'c lu cumnwnn (vmcHL-gy wmrdcling plulcliccx, 8 Conclusíons ln thn puídc. wc hawc dcscnkwd an nntnlngvy-dcvclopnrnt mclhodxültupy for dccluralivc fmmc- hasad Syktcnh, Wc listcd thc stcpx m thc ontolopy-dcvclnpmcnl proccss and dddrtsscd thc complcx hsuö uf dcfnning cluxs hicrmhics und pmpcmcs ni classcx und inxlunccs. Houtvcr. aftcr tullcaxving: nll thc rulcs and Supgcslluns. onc nf thc most nmpunam rhinps to rcmcmbcr Is thc followmg: rhcrc n- Im smg-lc rnrrvri ur| n'n! u;yx for un)" dmuuin. (hunltxgy design is u crcalnvc proccss und no lwn Lunlologlcts dcsngncd by dilfcrcnt pcuplc would be thc sumc. Thc putcntml
  24. 24. zlpplitállitíns m" thc nnmlnxxjy and (h: dcsigncvs anndcrsxunding und wicw nf lhv: dnmuín will unndnubuvdly uffccl cnnnlng) dvsign chaiccs. "Thc prml" is in thc pudaling"-xwc cun SLNNÜNN thc quality nfnur onlnlugy nnl) h) using it in JIppIÍCJIIÍOIIs for xshírh wc dnzsigunxí it, Acknowledgments Hxvlégú-ZIÍHK) (Illipggjjrggtgguxluníknwdxdg) xux dcvclopcd by Mark MuscnX gmup u! Summa! Mcdícul lnfunnnlics. Wc gcncralcd sumr nf lhc flgurcs wilh Un: OnlnViz plugínl ln Pnxlégé-ZÜIÍDO. Vvc impurtcd lhc inilinl vrmun u! lhc winc crmnlngy Írom thc Onlnlínguu crululugy libnugxv (hIlp: .". "'. -.unykxl sunnínrd CdUŐNÜÍVHv(IFCÍÜIHITIIIIELIEUII xmirh ín lum uscd u vcrxitm puhlishcd hy Bmchnum und uullzugucx (Bruchnum ct al. 1991) und (Iislriluulcd uilh lhc CLASSIC knmwlcdgc rrpmscluluuxvn systcun. Wc thcn mudificml thc (Imulugy m prrscnl cnnccpluul- nwdclirlg prinuplcs for dcclaralnc Írunzc-huscd UnIOÍOgÍCN. Ruy FcrgcrmnÍs und Mm Pclcgk cxlrnxix-c cumlnrrlls un cuulícr (IruÍls grcully ímpruvcd lhís papa-r. References Bmxxh. (i, Rulnbgau-Cíh. J. und Jncohxnn. I, ( I997). Tizr (Ím/ T: r! AIunG-Iing; h-u: cnnu_-, 'c' m: r guzizlr: Addixnn-Wcxlcy. Brachnun. R. J.. Hcfhxinncss. D. L.. Pulcl-Schncidcr. PJ-I. Rcsnick, LA. ami Bnrgida. A. 0199! b. lfn ing uith (ÍIJXSSIC: Whcn and hnu. m um- KL-(JNE-Iikc languugc. Prinríphnr ufSslnrtirzix Jvrttrtrríyi. J. F. Suwa, cditnr, hlorgzun Kaufnnzmlu: 40! --15(r. Bricklcy, D, Jml (juha. R. V. a; I909). Rcwurcc Dcscrigxticwn Fr-unrsuunrk (RDFD Schcmu Spen-iűruticm. Pmpnsrxl Recumnwndulicsnu. Wmld Vvidc Weh CUnxnrliLIIn: hllpi/ lxrss nm. 3.1Ir; :n'I'R/ 'PR-I1if-xchcnlau Chinusetu [2Í'. '.')0|. Chimurran Onlulcirgy limilnnnwent. ww wpksl NIUHÍ! lflLrtÍu/ xcIÜUtnIe/ (hilluleríl Duincvcld. AJ, Stnlcr. R, . SVcidorn. MR" Kcmépzn, B. und Bcnjamins, V. R. (Züfívíl). WnndxrrTuxwIVÍ A cnwparutisuor. slud) nfomcvlawgicul cnginscríng (mlx, IunAr: :uriu; .-ul Juuruu! nf Hunruu-Cruunyruiicr Srmhvx 52%]: I l I l-I I.33. Fálllluhül. A. ( I997). Ontolinguu tuturiatl httluz/ Asl Lwhxlzlllfvlxi cdxu/ pccxple/ Znxffttnlurinlpdf Gúnwz-Pórvsz. A. I IWSJV Knsm IPLIgC shuring ami ITLINC. H(tH(ÜJunÁ nfApjJ. 'it-tl Erprrl SLxIcI/ IA Lirhnxxiu, editor, CRC PYCNN. Gruhrr. T. R. 410931 A Trunxlatlinn Apprrunvh ln PHYIRIIVIC Ontnlxvg) Sponrifumliusux Knnulufg-r . -1r'qui. xirv'rur 5' I99 330. Gruniuxgcr. M and Fm, XI.5. i 19951. Níclltudtlhlgy' for thc Design and Eruluauiasxr uf Ontuluvgics. ln: PriI('P('(ÍIII_g'A uJ/ "rhc Wurühnp un Buxir 01.'a'i'ÍrI*u('('(lÍ Ixxum m Kmm Iulwr SÜUTÍILU. IJCJI-VÍ. Nhintlriul Hrmllcr. J. ami NícGuinun-ss. D. L. (ZHOD) Thv DARPA Agrm Mzxrktlp Langungv. Ilililí Inldltuvrzt S_'c. |'h"'III)' lólöb: 67-73 Humphrxgxux. B. L. and LindNIg. DAB. ( l993). Thc UMLS pmjccl: Inukhlg m; cuncuptuul cumwctiavn hcrxxxw-ru llsürs and thc infurnuutinsxt lhcy nccd. Elfut/ Ül q! Iiu- Din/ Jut! I, :Jvrc: :1x' . *1.T. 'í()('ltI| 'Ír'tJ? 8112): I 70. hlcGuinlzc-xs. D. L . Ahruhums. BATK. Rcxníck. LA" PulclvSchnc-idvr. P. I". . Thumusun. RJL. Cuuxlli-Sítnrm. V. and Cunuli, C. t I994). Cluxsíx" Knuwlcdgx" Rcpruxunlulitvn Syxlcnn Tuluriul. hllpJ/ xs u u . bcll-luhs. vonx/ prujucbfclaxsírfpupcrslClussTul/ Clus sTul hun] 24
  25. 25. NÍLTGUÍIIHxÍsS. D. L.. Fikcs. R. . Ricc, J. und XViIdcr, S. (2000). An Environlncnl for Nlcrging und Tcsting Lurgc ÜHIOIOgÍCN. Principlex nf Kmm huta-e Rvprc-svnutricnz und Rmxvmiuu: Pnwvrdlltgkx nfrhc Srwmh Inrcrnuriuunf ("rmfrrcncc- IKRZOWH, A. G. Cohn. F. Giunchiglia and B. Sclnum. cúitnrs. San Francisco, CA. hlorgan Kauflnann Publixhcrs, McGuinncss, D. l.. und Wright, J. (1998). (Tnnccptual Modclíng I'm Cnnügurnlinn: A Dcscription Lngic-hascd Appmnch. rlrlíjíriu! InrrlIigr-nrr jhr E! I_: ,'ÍItr't'll'II_L3 Dczcigu. Azmlyxix, und Manufsrcrrurirng - spc-criui iuzm m: (bn/ ilqururiun. Muscn, NLA. ( IWZ). Dimcnsíons of knowlcdgc sharing and rcusc. Compntrerx und Biumedirul Rrwrurlv 25: 435-467. (Mtolinguu ( IW7L Onlnlingmn Syslcnt Rcfcrcncc Ahnual. hltpzl/ xvwxnr-ksl- avustanfnrdx-du: 591 ŐÍÚOC/ ffálmc-CIÍÍIOTÍ i ndcxhlml Prlcc. (É, and Spacknmn. K. 12000). SNOMED clínical lcnns. BlHCáhl-I-Brítisl: Jemmal u] Heulrm-ure Cmnpulirgu á hzfurmatiun A-Iunugcvnrnl I7(3): 27-3I, Protcgc ( 20%). Thc Prmcgc Projccl. hupz/ lprolcgcxlznnfewrdxdu Rnsch. F. |_ I978). Principlcs of Gutcgcwrizaxtiavn. Cumuiínn ami Cru: --_s, -uri: urin: :. R. E. and B. B. Lloyd. cditors. Hillsidc. NJ. Luwrcncc Etlhxulnxx) Publishcux: 27-48. Rothennuh. T. R.. Gennuri. J. H.. Erikwvn. H. , Puenu. A. R.. Tu. S. WT und hímen. Mmfk. (_|996). Rcusublc amolngícx. knnwlcdgc-zacquisition iools. und pcrfonnznxmcxt syslatmx: PROTEGE-Il wululitvns (u Sisyphux-Z. Inlcrnarinncx! Juurnuf ujHumttn-Curzxprctvr Szadit: 44: 303-332. Ruunhuugh. 1.. Blaha. W. hcrlvcrlami. W. . Eddy. F. und Lnrcnsm. W . l, [99] ). OIgn-rI-rtrivrxicti mmlclurg und drsign. Englcvxood C Iiffs. New Jcnwy: henticc Hull. Lkcholci. M. and Gruninger. M. ( I996). Onlolngíex: Ptinciplex. Níethods and Applicalions Knmrlczlgc Engitrcrring Rrvirw ll(2). Is) U!

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