A Novel Global Measure Approach based on Ontology Spectrum to Evaluate Ontology Enrichment

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1 A Novel Global Measure Approach based o Otology Spectrum to Evaluate Otology Erchmet Karm Kamou Faculty of Sceces of Tus, Uversty of Tus El Maar, Tusa ABSTRACT I the cotext of otology evoluto real world applcatos, partcularly the feld of sematc web, otologes are called to chage ther structure as well as ther sematc. It s ecessary to evaluate the qualty based o stablty to make aalyss to get approprate erchmet maer for otology evoluto. I ths paper, we troduce a ew approach wth that ams makg three cotrbutos. Frst, we preset a ew aspect of otology qualty based o ts stablty. Secod, we preset a ew oto called otology spectrum whch ca be used for aalyzg otology stablty. Thrd, we provde a expermetal method to evaluate ths ew aspect of qualty wth two processes: dvdual measure based o sematc smlarty measures ad global measure based o otology spectrum. Keywords Otology evaluato, sematc smlarty measure, otology erchmet, otology qualty, otology stablty. 1. INTRODUCTION The Web s evolvg toward the Sematc Web, whch the sematcs of Web cotet s defed, makg the Web meagful, uderstadable, ad mache-processable [1]. Otologes stad as a key compoet of the Sematc Web sce they are the backboe of kowledge represetato; thus, they ca be corporated to computer-based applcatos ad systems to facltate data aotato [2], decso support [3,4], formato retreval, ad aturallaguage processg [5] ad serve as a tegral part of the Sematc Web. Otologes are a very advaced tool of kowledge represetato, for orgazg the kowledge of a wde area of expertse. However, the sources of formato, usually documetares, costatly chagg both the used vocabulary ad the meag of the elemets cotag t. Otologes eed, therefore, to be kept up-to-date so that the depedet systems rema operatoal. Followg a update or more partcular, a erchmet, otology should be evaluated order to exame ts qualty. t s mportat to determe whether that otology s actually mprovg over tme (becomg more complete ad correct), or whether chages to the otology had a egatve effect, makg the otology less cohesve ad correct ad decreasg ts qualty. A wde varety of evaluato methods have bee proposed such as descrbed [6, 7, 8, 9]. These methods dffer that they have dfferet terpretatos of qualty. I ths paper, we look for evaluato approaches based o the use of otology real world cotext. I ths cotext, related works are cosdered to be dvdual measures [8,1,12] that evaluate dvdual cocepts or query results of the otology. I ths work, we troduce a ovel global evaluato measure approach for otology evoluto partcularly for erchmet. Sadok Be Yaha Faculty of Sceces of Tus, Uversty of Tus El Maar, Tusa Ths global measure wll cosder the otology stablty wth metrc depedet to the umber of cocepts, order to make erchmet evaluato betwee otologes wth dfferet cardaltes. The remader of ths paper s orgazed as follows. Secto 2 postos ths paper wth the related work ad motvates our proposed approach. I secto 3, we descrbe the ew aspect of qualty based o otology stablty wth dvdual smlartes measure. Ths s followed, secto 4, by a descrpto of ew approach, called global stablty measure, for aalyzg otology stablty based o otology spectrum. I secto 5, we preset ad dscuss the results of two expermets order to valdate our approach. Secto 6 brefly recalls our cotrbutos ad sketches aveues for future work. 2. RELATED WORK I ths secto, we scrutze the related work that sugess to our work. Ths state of the art s focused o two parts: the otology evaluato ad sematc smlarty measures. 2.1 Otology evaluato Otology s evaluato s a area of research that has emerged farly recetly, several approaches exsts the lterature puttg the focus o that topc[6,7,8,9] These approaches maly dffer the way ad the crtera chose to evaluate the evolved otology. We dstgush varous evaluato approaches to fve categores whch are global stadard approach, applcato based approach, data drve approach, huma udgmet approach ad structural approach. 1- The frst approach, called the gold-stadard approach [1], attempts to assess the qualty of otologes usg gold stadard otology. I ths approach, the gold stadard otology s regarded as a well costructed oe. It could be aother exstg otology, or t could be take statstcally from a corpus of documets or prepared by a doma expert. The cocepts of a costructed otology are evaluated by comparg them vs those of the gold stadard otology. Typcally, the gold stadard approach s used to evaluate a otology geerated by a learg process. 2- The secod oe s a applcato-based approach [1] whch the qualty of the otology s evaluated based o ts actual use a real-world applcato [11]. The output of the applcato or ts performace o the gve task mght be better or worse depedg o the otology of use. Otologes may therefore be evaluated smply by pluggg them to a applcato ad evaluatg the results of such applcato. Orme et al.[8], exame the qualty, completeess, ad stablty of otology data as far as otology evolves. They propose a metrcs sute, based o stadard software qualty cocepts, to assess the 23

2 complexty ad coheso of otology data o oe had, ad determe otology completeess ad Stablty for evolved otology o the other had. 3- The thrd approach s data-drve sce t evaluates the qualty of otology by measurg the ft betwee the otology ad the corpus of a problem doma to whch t refers. I ths approach otology s evaluated oly at the lexcal level [12]. 4- The fourth approach reles o huma udgmet. I the latter, the evaluato s carred out by doma experts whom try to evaluate how well the otology meets a set of predefed crtera, stadards, ad requremets. Our approach belogs the secod category. 5- The ffth approach used metrcs operatg followg crtera [14]: complexty, coheso, modularty, abstracto ad taxoomy. I the same vso, the approach OtoQA (Metrc-Based Otology Qualty Aalyss) by Tartr et al [15], s worth of meto. The latter proposes a battery of metrcs dvded to two related categores: schema metrcs ad stace metrcs. The frst category evaluates otology desg ad ts potetal for rch kowledge represetato. The secod category evaluates the placemet of stace data wth the otology ad the effectve usage of the otology to represet the kowledge modeled the otology. I our work we stad wth the secod category descrbed by Brak et al [1,12], the applcato-based approach category, sce we cosder that otology was foud to be used by a applcato, so ay chages otologcal data drectly affects otology based systems. Therefore, t would be more relable to evaluate the otology wth respect to ts actual use ad test ts performace agast expected results by users. Otologybased applcatos, as do other approaches, geerally use sematc smlarty measures that explore the otology ad fulfll the eeds of the applcato. 2.2 Sematc smlarty measures Geerally otology has a structure of cocepts whch the relato of subsumpto (subclassof) s the prmary relatoshp. Ths structure defes the sematcs of these cocepts. The measures that explot ths structure are called sematc measures of cocepts. Sematc measures ca thus evaluate a lk betwee two cocepts of the same otology by explotg ther relatoshp. Accordg to [16], varous forms of sematc smlarty measures ca be classfed to three types: measures that focus the characterstc of otology s ettes, sematc relatoshp measures ad formatoal cotet measures. For the frst, based o characterstc of otology s ettes, the smlarty measure betwee two cocepts s defed as a process of matchg characterstcs. The gve smlarty s based o both commo ad dfferet characterstcs of those two cocepts [17, 18, 19, 2]. For the secod, based o sematc relatoshp, Rada et al. [21] proposed a metrc to measure coceptual dstace betwee A ad B herarchcal s-a sematc ets. The dstace betwee A ad B s equal to the mmum umber of edges separatg A ad B. Wu ad Palmer[22] depedg o mscs(c;c ) whch refers to the most specfc subsume (the lowest commo acestor the tree) of both cocepts C ad C. Other works lookg at mprovg measuremet accuracy by cosderg other sematc lks addto to subsumpto [23,24]. The thrd type, based o formatoal cotet, dstgushes betwee two categores of measures. Those usg textual corpus ad others usg otology structure: - For the frst category, Resk [25], Jag ad Corath [26] assocates a probablty p wth cocepts a s-a herarchy to deote the lkelhood of ecouterg a stace of a cocept c a textual corpus. - For the secod category, Seco et al [27], Blachard et al [28] preset, respectvely, ew method for computg the formato cotet of cocept by cosderg oly the taxoomc structure of the otology. I the cotext of secod category wth formato cotet based o otology structure, Blachard et al [28] proposes four hypothess of stace dstrbutos. The frst hypothess, P p, focuses o a uform dstrbuto amog the cocepts wth the same profoudess; the formato cotet of a cocept depeds bascally oly o ts profoudess. The secod hypothess, P s, mples a uform dstrbuto amog the set of sos of each cocept, the formatoal cotet of a cocept depeds o the umber of sblg of the subsumg cocepts. The thrd hypothess, P g, proposes a uform dstrbuto amog the set of leaves of the otology. The more leaves a cocept has, the less mportat ts formatoal cotet would be. The fourth ad the last hypothess s P h, t focuses o the prcple that the cocepts of the same heght should carry the same formato cotet. The same authors Blachar et al propose a ew measure PSS the Proporto of Shared Specfcty [28] whch takes to accout the desty of lks the graph betwee two cocepts. Ths measure s based o hypothess P s descrbed above ad takes the form of the Dce measuremet. We ca characterze all those descrbed measures as dvdual measures of smlartes. Ths ca be explaed by the fact that t ca dvdually measure the smlarty of cocepts. The qualty evaluato approach we are gog to propose ca be appled for varous smlarty measures partcular the PSS measure. As we have descrbed prevously, we focused ths paper o the evaluato qualty of otology based o ts actual use real word applcatos. Otology based applcato ca use sematc smlarty measure to explot otology structure. I the ext secto, we preset the aspect of qualty based o stablty whch ca be compute usg sematc smlarty measure. 3. APPROACH OF STABILITY BASED ON INDIVIDUAL MEASURES The most useful approach of otology qualty evaluato s the oe based o the use of the otology real world applcato. The user of otology based system s terested the respose to ther request queres. Thus, ths work, we are terested ths category of qualty evaluato of otology I the cotext of otology erchmet, we preset evaluato qualty of otology based o the stablty of respose for smplfed request queres. Ths respose s based o smlarty measures to get sutable cocept results from those queres. For complex queres, t ca be cosdered as combato of smplfed oes. We call ths evaluato approach: a based dvdual measure evaluato. If ths measure stll uchaged for otology erchmet, the 24

3 otology wll be cosdered to be stable. Ideed, accordg to query resposes, a stable otology has ot sgfcat chages throw erchmet. We look for the stablty of the results regardg otology evoluto or more precsely otology erchmet. Hece, we propose a ew approach whch ca be preseted as a obectve to choose the best way to erch the otology. Let us cosder two otologes O1 ad O2 where O2 s a evoluto of O1 after erchmet of ths oe. N stads for the cardalty of O1. We compute the smlarty of the commo set of cocepts betwee O1 ad O2 order to fd the sematc ad structural stablty of cocepts followg evoluto. Ths smlarty s computed usg the average of the smlartes betwee the cocepts of dfferet otologes. Sm_commo( O, O ) 1 2 O1 O1 sm( c, c ) sm( c where s the cardalty or the umber of cocepts cotaed O2, c O 1 ad O 2 s the erchmet result of O 1 O ) O2 ( 1 O2 ) (1) O C 1 represets the cocept C otology O 1 ad Sm_commo s the sematc smlarty measure betwee two cocepts. I our cotext, to evaluate the qualty of the otology after erchmet, we must rely o a set of queres to evaluate ther results regardg the tal otology ad ts erchmet. The queres are maly based o research cocepts usg sematc smlarty measures. To be geerc over queres submtted by the user, we make a exhaustve ad smplfed comparso of requests by smlarty betwee cocepts. Ideed, ay query s a combato of a smple query search of a sgle cocept. Applyg the sematc smlarty measure based o the formato cotet PSS (Proporto of shared specfcty) [28], descrbed above, to both otologes koala (v) ad koala.owl we obta two tables cotag the values of smlarty measures betwee pars of cocepts belogg to the same otology. Tables 1 ad 2 represet part of the smlarty measures of commo pars of otology s cocepts before erchmet koala(v).owl ad after erchmet koala.owl. Iterestgly eough, there are pars of cocepts whose smlarty values has chaged after erchmet. For example, the par of cocepts (Paret, Marsupals), the smlarty value Table 1 s equal to.721, ths value becomes.62 the secod table, whch makes a dfferece of.11. Fg1:Ital otology Koala(v).owl. Fg2: Erchmet otology Koala.owl. The value of Sm_commo belogs to [,1]. Wheever ths value teds to, ths meas that the cocepts of the otology mata almost the same sematc values after evoluto. We take a llustratve example of a smple otology amed koala.owl [29] defed by Kublauch the referece ste of Protege-OWL. The otology Koala.owl cludes 2 cocepts except the cocept of the vrtual root (owl: Thg). It descrbes the cocepts related to humas ad marsupals (subclasses of mammals). We have removed radomly from ths otology seve cocepts order to obta a tal otology koala (v) that cludes 13 cocepts whch we erch wth 7 cocepts that we have removed to fally reach our prste otology koala.owl. The fal otology s the erchmet result wth the sub trees of cocepts Perso ad Forest (c.f. Fgure 1ad 2). 25

4 .. Iteratoal Joural of Computer Applcatos ( ) Table 1.Smlarty measure of cocepts pars of otology Koala(v).owl. Koala Marsupals Uversty Paret Amal. Habtat Koala 1,819,591,667. Marsupals,819 1,721, Uversty 1 1 Paret,591,721 1,883 Amal,667,838, Habtat 1. 1 Table 2. Smlarty measure of cocepts pars of otology Koala.owl after erchmet. Koala Marsupals Uversty Paret Amal. Habtat Koala 1,84,521,62. Marsupals,84 1,62, Uversty 1,838 Paret,521,62 1,765 Amal,62,765, Habtat, Whereas the par of cocepts (Koala, Marsupals) the dfferece of both measuremets before ad after erchmet s equal to.21 (= ). These varatos ca be explaed by the fact that the measure used PSS s based o the formato cotet usg the P s hypothess whch depeds o the umber of brothers of the subsumg cocepts ad the erchmet affected ths structure. I order to check the smlarty measures dfferece of commo pars of cocepts betwee two otologes, we calculated the average smlarty measure prevously show formula 1 by Sm_commo, the result s: Sm_commo(Koala(v),Koala) =,13. The varato of Sm_commo value depeds essetally o the sematc smlarty measure used. There s some measures whch are more sestve to some types of chages the otology structure durg erchmet. I our example, the sematc smlarty measure used dd ot really affect the value of Sm_commo, sce the erchmet dd ot touch sgfcatly the structural relatoshps o whch depeds the smlarty measure PSS. Therefore, we evaluated the sematc stablty for commo cocepts betwee otology Koala (v) ad ts erchmet Koala. I ths dvdual measure based approach, the ew cocepts added (lke the cocept Perso or Forest) the otology Koala, ca be evaluated oly after a ew evoluto. Ths costrat s the maor lmtato to use dvdual measures of smlartes (Sm_commo) to evaluate the otology sematc stablty. Lookg for a alteratve maer to evaluate sematc stablty eve for ew added cocepts, would be a good challege. I the case where these ew cocepts mata almost the same sematc ad structural aspects of the otology, the otology wll be cosdered as stable. I the opposte case, otology chages the appearace of ts structure ad therefore the erchmet causes a loss of otology stablty. For ths requremet, we defe a ew global smlarty measure of stablty stead of the dvdual oe based o the commo cocept set. Fgure 3 shows a example of otology O 1, cosstg of four cocepts C 1, C 2, C 3 ad C 4, whch has bee a erchmet of 3 other cocepts C 5, C 6 ad C 7 ad obta a ew otology O 2. The stablty evaluato usg dvdual smlarty measure cosder oly the set of commo cocepts C 1,C 2,C 3 ad C 4, whle the use of a global smlarty measure should deal, addto, wth ew cocepts added C 5, C 6 ad C 7. O 1 C 1 C 2 C 3 C 4 Fg 3: Lmt of dvdual smlartes measures 4. GLOBAL STABILITY MEASURE I ths secto, we preset a ovel measure called global smlarty measure. It s based o the oto of sematc smlarty measures frequecy of otology. We cosder dvdual smlarty measure for each both cocepts of otology. Ther values ca descrbe the otology stablty. To be depedet to the umber of cocepts, we defe a global measure based o the frequecy of dvdual smlarty measure. Those frequeces are computed by tervals. Thus, each terval of smlarty, we compute the umber of cocepts smlarty measure values. Ths ew measure s terpreted by the oto of frequecy measures that defes the spectrum of otology. The frequecy oto cossts of coutg the umber of smlarty measures values belogg sample terval, wth sze Δs, cluded [..1]. We take the example of Koala otology [29]. Usg the sematc smlarty measure PSS [28] ad cosderg tervals of sze Δs =.5, we get the table of values (c.f. Table 3) ad the hstogram show Fgure 4. C 7 C 5 C 6 O 2 26

5 ],,5] ],,5] ],5,,1] ],5,,1] ],1,,15] ],1,,15] ],15,,2] ],2,,25] ],15,,2] ],25,,3] ],2,,25] ],3,,35] ],25,,3] ],35,,4] ],3,,35] ],4,,45] ],35,,4] ],45,,5] ],4,,45] ],5,,55] ],55,,6] ],45,,5] ],6,,65] ],5,,55] ],65,,7] ],55,,6] ],7,,75] ],6,,65] ],75,,8] ],65,,7] ],8,,85] ],85,,9] ],7,,75] ],9,,95] ],75,,8] ],95, 1] ],95, 1] ],9,,95] ],85,,9] ],8,,85] Iteratoal Joural of Computer Applcatos ( ) Table 3. Smlarty values frequecy. Iterval frequecy Fg 4: Spectrum of otology Koala.owl. For the smlarty terval ].5,.55], there are 12 measures of cocepts pars belogg ths terval. We also ote a sgfcat umber (146) of measures set to, ths reflects that may cocepts have o sematc relatoshp wth the smlarty measure used. Each otology ca be characterzed as a spectrum of smlarty measure (see fgure 4). I order to measure stablty, we compare otology spectrum features before ad after erchmet. If we keep the same pace of spectrum, the we ca estmate that the otology remas stable, because smlartes proportos betwee cocepts are mataed. I order to have a smplfed measure of smlarty measures frequecy spectrum, we rely o the formalsm descrbed the ext subsecto. 4.1 Stablty measure formalsm Frequecy spectrum of otology Spect O (S) compute the umber of smlarty values betwee all cocepts sm C, C ) terval of sze s. For a gve value of O( smlarty s, the followg expresso s used to calculate the umber of cocepts wth a smlarty measure cludg the terval s s. * s, 1 * s s s s[,1], Spect ( s) 1 1 O s s ( smo ( C, C ) * s)* (( 1)* s smo ( C, C )) s (2) s Where Sm O s the smlarty fucto betwee cocepts, t ca be computed by usg the smlarty measure PSS. For example, for the smlarty value s =,12 ad s =,5, we have the lower boud of the terval: s,12 * s *,5 2*,5,1,5 s ad the upper boud: s,12 ( 1)* s ( 1)*,5 3*,5,15,5 s Thus, the value s =,12 belogs to the terval ].1,.15]. The fucto δ havg the value 1, allows to cosder the smlartes the specfed terval. I fact, we have s s ( smo ( C, C ) s smo C C s s * ) 1f (, ) s * Otherwse, the value of δ wll be equal to. The spectrum computes smlarty values frequeces that deped o the umber of cocepts cludg otology. I order to make ths fucto depedet of the otology sze, we gve ts ormalzed expresso: Spect O ( s) s[,1], SpectN O ( s) 2 (3) where s the umber of cocepts for a gve otology O ad s s a sematc smlarty measure. Wth ( x) 1s x ( x) s x 27

6 To evaluate otology stablty durg erchmet process, we determe the dfferece betwee spectrums before ad after erchmet respectvely defed by O 1 ad O 2. The followg expresso computes the average dffereces betwee ormalzed spectrums of two otologes O 1 ad O 2. SmGlob( O, O ) s 1 Wth s * s et s [,1]. SpectN O1 ( s ) SpectN 1 s O2 ( s ) (4) We ote that f SmGlob coverges to, we ca deduce that we have two smlar spectrums represetatve of two otologes, ad therefore the otology O1 mataes the same varato of sematc smlarty measures eve after erchmet to the otology O2. Ths ca be resulted a stablty of otology regardg erchmet. 5. SIMULATION AND VALIDATION Our ew global evaluato approach s evaluated wth varous smulatos to compare wth the classcal dvdual oe as [1, 12]. We realzed automatc geerator of vrtual otology reduced taxoomes based o structural propertes. The geerator creates radom taxoomc structures of cocepts, bult based o a subsumpto herarchy (tree structure), ad export the results to otologes descrbed wth OWL laguage. The geerator takes as put a umber of structural crtera that must be followed durg the costructo of radom otologes. The crtera chose are : - The umber of odes or cocept of the otology; - The umber of leaves of the tree represetg the otology; - The depth of the tree; - The Average sos per ode ; - The rato R= Max ( umber sos by cocept (ot cludg leaves) M( umber sos by cocept (ot cludg leaves) - The varace E: t s a dfferece betwee the depth of the tree bult ad the mmum depth of a leaf. The geerator wll be used to radomly geerate a tal otology ad also erchmet by addg radom cocepts. I all smulatos, we rely o two types of erchmet: poor ad mportat. For poor erchmet, the sze of the tal otology s 5 cocepts, ad the fve erchmets are performed each tme wth a addto of a sgle cocept. Cocerg mportat erchmet, we start wth otology cludg 15 cocepts ad the we erched t fve tmes wth addg successvely a mportat umber of cocepts: 3, 5, 9, 12 ad 15. We frst compare our proposed approach o the otology stablty, based o global smlarty wth the dvdual approach smlar to several research such as descrbed [1]. Next, we study the mpact of erchmet volume o the stablty of global smlarty value. 5.1 Comparso betwee global smlarty ad dvdual smlarty I the followg, we wll look for the correlato terpretg the dfferece betwee global ad dvdual smlarty relato to the mportace of cocepts umbers erched wth. To crease the umber of smulato samples for a more sgfcat study of correlato, we start wth three tal otologes radomly costructed, for each oe we made fve erchmets whch gve a total of 15 samples. I the case of poor erchmet, the correlato value of Peterso s,94 close to 1 (fgure 5). Ths dcates that the global ad dvdual smlarty measure have the same sematc terpretato. However, global smlarty presets a addtoal advatage over the dvdual oe the ablty to evaluate addto the qualty of ew erched cocepts. Idvdual smlarty evaluates the qualty the pot of vew of stablty by computg smlarty betwee two otologes wth same sze. That s why, t s appled to the commo set of cocepts betwee otology ad ts erchmet. Whereas, the global smlarty s depedet of the cocepts umber otology, ad ca be appled geeral case. For mportat erchmet, there wll be a more sgfcat dfferece betwee otology ad ts erchmet. Because global smlarty processes all cocepts ad dvdual smlarty deals oly wth the commo set of cocepts betwee otologes, the correlato value has decled sgfcatly ad s equal to.756 (fgure 6) compared to.941 the prevous fgure (fgure 5) for poor erchmet R² =.94 Fg 5: Correlato betwee dvdual ad global smlarty measure for poor erchmet dvdual ad global smlarty Lear (dvdual ad global smlarty) dvdual ad global smlarty Lear (dvdual ad global smlarty) R² = Fg 6: Correlato betwee dvdual ad global smlarty measure for mportat erchmet. 28

7 SmGlob SmGlob Fg 7: Global smlarty measure betwee tal otology ad after a umber of erchmet. Fg 8: Global smlarty measure betwee two successve otologes before ad after erchmet. Sce the proporto of all commo cocepts becomes less mportat tha the erched cocepts, the dvdual smlarty measure becomes effcet. Ths reflects the weakess of the correlato wth global smlarty measure. So, wheever the umber of erched cocepts teds to, the dvdual measure would be more accurate for evaluatg otology stablty. I ths case, we showed that our global smlarty approach has very strog correlato wth the dvdual measure. I geeral case, whe the erchmet s mportat, the dvdual measure s lmted to terpretg the qualty based o stablty, the correlato becomes lower. Thus, our global smlarty approach s hghlghted. 5.2 Impact of erchmet volume o the stablty of global smlarty measure I ths smulato, we take a tal otology cotag 2 cocepts ad fve erchmets are doe each tme wth the addto of fve cocepts. We focus o the varato of global smlarty measure relato wth erchmet. I Fgure 7, we determe the global smlarty betwee tal otology ad otology after k erchmets; k vares from 1 to 5. The smlarty s gradually creased, but wth a smaller gradet, we ote that the otology become more stable relatve to the crease of ts sze. Fgure 8 presets the overall smlarty betwee two successve otologes regardg erchmet. Ths dfferece becomes smaller, cofrmg the same terpretato as the prevous fgure 7 that the otology s gradually stablzed after successve erchmet. 6. CONCLUSION To evaluate otology stablty wth regard to erchmet, we have proposed two geeral approaches: the dvdual measure as classcal oe ad the global measure. The global oe descrbes otology wth frequecy spectrum of cocepts smlarty measure. Ths ew measure approach reflects smple request query lookg for cocepts of otology. It s cosdered the cotext of usg otology real world applcato. Our spectrum evaluato approach gves a automatc stablty evaluato of otology wth regard to erchmet. We performed the effcecy of global measure approach by smulatos makg radom otology costructo ad erchmet. Our approach has smlar results to classcal oe the case of poor erchmet. However, t overcomes the lmtato of classcal approach to evaluate a hgher erchmet. Moreover, we have here restrcted ourselves to a herarchcal structure deduced from the s-a lk ad the use of oly oe sematc smlarty measure PSS. Although ths structure s kow to be the most structurg of a real-lfe otology. As future work, we wll attempt to geeralze our approach to a graph structure to smultaeously take other lks to accout. I addto we wll try to use other smlarty measure ad combe them order to explot all aspects of otology structure. 7. REFERENCES [1] T. Berers-Lee, J. Hedler ad O. Lassla. The Sematc Web, Scetfc Amerca 284:34 43, 21. [2] MA. Muse. Otologes bomedce. AMIA 28 tutoral T26. Washgto, DC, November 9; 28. [3] AC. Yu. Methods bomedcal otology. Joural Bomed Iform;39:252 66, 26 [4] MA. Muse Scalable software archtectures for decso support. Methods If Med; 38:229 38, [5] DL Rub, SE Lews, CJ Mugall, S. Msra, Westerfeld M Ashburer, et al. Natoal Ceter for Bomedcal Otology: advacg bomedce through structured orgazato of scetfc kowledge. OMICS 26; 1:185 98, 26. [6] A. Burto-Joes, VC. Storey, V. Sugumara, P Ahluwala. A semotc metrcs sute for assessg the qualty of otologes. I proceedg of Data ad Kowledge Egeerg 25; 55(1): 84 12, 25. [7] A. Gagem, C. Cateacc, M. Caramta, J. Lehma, A theoretcal framework for otology evaluato ad valdato. I Proceedgs of the Sematc Web Applcatos ad Perspectves (SWAP), 2d Itala Sematc Web Workshop, Treto, Italy, 25. [8] A.M. Orme, H. Yao, ad L.H. Etzkor, Idcatg otology data qualty, stablty, ad completeess throughout otology evoluto, Joural of Software Mateace, 49-75, 27 [9] G. Beydou, A.A. Lopez-Lorca, F.G. Sáchez, ad R. Martíez-Béar, "How do we measure ad mprove the qualty of a herarchcal otology?", Joural of Systems ad Software, ,

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