ERIC EJ1135021: The Role of E-Vocabularies in the Description and Retrieval of Digital Educational Resources

2017·11.4 MB·English

by  ERIC

education
sciences
Review
The Role of E-Vocabularies in the Description and
Retrieval of Digital Educational Resources
AnaM.Fernández-Pampillón
FacultaddeFilología,UniversidadComplutensedeMadrid,Av.Séneca,2,28040Madrid,Spain;
apampi@filol.ucm.es
AcademicEditor:JamesAlbright
Received:21November2016;Accepted:4February2017;Published:1March2017
Abstract: Vocabulariesarelinguisticresourcesthatmakeitpossibletoaccessknowledgethrough
words. They can constitute a mechanism to identify, describe, explore, and access all the digital
resources with informational content pertaining to a specific knowledge domain. In this regard,
theyplayakeyroleassystemsfortherepresentationandorganizationofknowledgeinenvironments
in which content is created and used in a collaborative and free manner, as is the case of social
wikisandblogsontheInternetoreducationalcontentine-learningenvironments. Ine-learning
environments, electronic vocabularies (e-vocabularies) constitute a mechanism for conceptual
representation of digital educational resources. They enable human and software agents either
to locate and interpret resource content in large digital repositories, including the web, or to use
them(vocabularies)asaneducationalresourcebyitselftolearnadisciplineterminology. Thisreview
article describes what e-vocabularies are, what they are like, how they are used, how they work,
andwhattheycontributetotheretrievalofdigitaleducationalresources. Thegoalistocontributeto
aclearerviewoftheconceptswhichweregardascrucialtounderstande-vocabulariesandtheiruse
inthefieldofe-learningtodescribeandretrievedigitaleducationalresources.
Keywords: vocabularies;e-vocabularies;digitaleducationalresources;digitalresourcesretrieval;
informationretrieval;e-learning;lexicography
1. Introduction
Vocabulariesarelinguisticresourcesthatmakeitpossibletoaccessknowledgethroughwords[1].
In this regard, they can constitute, in their digital format, a mechanism to identify, describe,
access, andexploreallthedigitalresourceswithinformationalcontent(e.g., documents, websites,
and educational software) pertaining to a specific knowledge domain [2,3]. Thus, they play a key
roleassystemsfortherepresentationandorganizationofknowledgeinworkenvironmentsinwhich
informationiscreatedandusedinacollaborativeorfreemanner,asisthecaseindigitalteachingand
learningenvironments,e-learningenvironments,ortheweb[4].
E-learningenvironmentsarespacescreatedontheInternetwhichintegratedigitaleducational
resourcesasafundamentaldidacticcomponent. E-learningenvironmentscurrentlyconstituteone
ofthebasicelementsineducationalinstitutionsandinprofessionaltrainingandupdatingservices.
Bydigitaleducationalresources,alsoknownaslearningobjects,weunderstanddigitalentities(filesor
filegroups)whichhaveatleastonedefinedlearningobjective. Someexamplesofdigitaleducational
resourcesarevideolessons,e-books,presentations,notes,exercises,andassessments. OntheInternet,
digitaleducationalresourcesareusuallylocatedineducationaldigitalrepositories(alsoknownas
LearningObjectRepositories). Aneducationaldigitalrepositoryisanonlinesystemtostore,publish,
retrieve,andreuseeducationalresources[5]. TwogoodexamplesareMERLOT[6]andARIADNE[7].
Themainadvantageoftheserepositoriesisthattheyfacilitatetothemaximumlocationandselection
Educ.Sci.2017,7,33;doi:10.3390/educsci7010033 www.mdpi.com/journal/education
Educ.Sci.2017,7,33 2of38
oftheresourcessoughtaswellastheirintegrationine-learningenvironments,suchasvirtualcourses
invirtualcampuses. Tofacilitatethelocationandselectionofresources,mechanismsforidentification
anddescriptionareused—mainlymetadataande-vocabularies.
Thisreviewarticlefocusesononeoftheaforementionedmechanisms: e-vocabularies. Thearticle
describes,usingasemasiologicalapproach,whatvocabulariesare,howtheyareused,howtheywork,
and what they contribute to retrieve digital educational resources. The final goal is to answer the
mainquestion—whatisthepositionandpurposeofe-vocabulariesinthedescription,organization,
andretrievalofdigitaleducationalresourcesusedine-learningenvironments?
Toanswerthisquestion,adeductive–inductivemethodbasedonsuccessiverefinementshasbeen
applied. Starting from a theoretical core and a data sample, a double analysis is conducted going
(1)fromtheorytothesampleand(2)fromthesampletothetheory,comparingandtryingtofitthe
theoretical proposals with the sample items. The theoretical core comprises the works presented
in[8–10],andthesamplecomprisestherelevantexamplesofopeneducationalrepositories[6,7,11,12],
picture[13–16],andvocabularies[17–26]).
When a fit is found, that is, when a theoretical proposal used in any of the sample items is
foundorviceversa,theanswerisrefinedbysearchingintheliteratureforinformationthatmakesit
possibleto(a)godeeperintothetheoreticalproposal;and(b)verifythatithasbeenappliedtoother
relevantexamples.
Finally,theresultsarepresentedinthearticlefollowingthesamedeductive–inductiveformat
as in the analysis: the theory and the actual examples that support it. The article is structured to
answerthemainquestionincrementally,bysteps:Section2providesadiscussionofwhatavocabulary
is; Section 3 discusses what a vocabulary is like; Section 4 focuses on how vocabularies work in
InformationRetrieval;Section5specializesSection4todigitaleducativeresourcescomingincreasingly
closetothemainquestion: howvocabulariesareusedtodescribeandretrievedigitaleducational
resources; Section 6 answers how to describe digital educational resources albeit refining in each
possible e-vocabulary type. Finally, Section 7—the summary and conclusions—answers the main
questionandprovidestheviewfromtheauthoraboutwhattheroleofe-vocabulariesinthedescription
andretrievalofdigitaleducationalresourcesis.
2. WhatIsaVocabulary?
The term vocabulary is ambiguous, and its meaning depends on the discipline of which it is
part and the context in which it is applied. For example, in the general knowledge domain of
alanguagesuchasSpanish,“vocabulario”hassevenmeanings(Figure1): “(1)thesetofwordsin
a language; (2) a dictionary (book); (3) the set of words used in a region, a profession, a writer’s
semanticfield,etc.”,orsimply“(4)thebookinwhichtheyareincluded;... ”[27]. Inmorespecialized
domains,vocabularieshaveamoreprecisemeaning,form,andapplication. Insuchdomains,aword
(or collection of words in several languages) designates a single concept which is called a term
and the set of terms is called a terminology [28,29]. Although vocabulary is not synonymous with
terminology,vocabularywillbeusedinthisarticletocovernotonlywordsingenericlanguagealso
butdomain-specificwords(e.g.,theInternationalStandardizationOrganization,ISO,usestheterm
vocabularytodenotesomeoftheirterminologystandardssuchasISO472:2013-Plastics—Vocabulary).
Additionally,ifvocabulariesarebuiltandusedinelectronicformat,theyarereferredase-vocabularies.
Sincethemajorityofvocabulariesarenowbuiltinelectronicformat,throughouttherestofthearticle
“vocabularies”and“e-vocabularies”areusedinterchangeably.
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Educ. Sci. 2017, 7, 33 3 of 39

FFiigguurree 11.. SSeevveenn mmeeaanniinnggss ooff tthhee wwoorrdd ““vvooccaabbuullaarryy””,, ““vvooccaabbuullaarriioo”” iinn SSppaanniisshh ((ssoouurrccee:: [[2277]]))..
In the domain of Library and Information Science, a vocabulary is called term vocabulary and it is
In the domain of Library and Information Science, a vocabulary is called term vocabulary and
defined as a set of terms of conventional syntactic procedures used to represent the contents of a
itisdefinedasasetoftermsofconventionalsyntacticproceduresusedtorepresentthecontentsof
document in order to retrieve it [30,31]. They are also known as documentary languages and provide a
adocumentinordertoretrieveit[30,31]. Theyarealsoknownasdocumentarylanguagesandprovide
common, universal system for classification of bibliographic works and documents [31].
acommon,universalsystemforclassificationofbibliographicworksanddocuments[31].
This concept is also shared by the vocabularies used for Information Retrieval (hereinafter, IR).
ThisconceptisalsosharedbythevocabulariesusedforInformationRetrieval(hereinafter,IR).
In this domain, vocabularies are used as components of the IR software systems to prevent linguistic
Inthisdomain,vocabulariesareusedascomponentsoftheIRsoftwaresystemstopreventlinguistic
ambiguity and polysemy [8]. These are controlled vocabularies that are defined as lists of terms,
ambiguityandpolysemy[8]. Thesearecontrolledvocabulariesthataredefinedaslistsofterms,explicitly
explicitly listed, unambiguous, and non-redundant which contribute a conceptual description and a
listed,unambiguous,andnon-redundantwhichcontributeaconceptualdescriptionandapragmatic
pragmatic and empirical dimension to the information domain.
andempiricaldimensiontotheinformationdomain.
In the field of Computational Linguistics, Natural Language Processing, and Linguistic
In the field of Computational Linguistics, Natural Language Processing, and Linguistic
Technology, vocabularies are also called computational lexicons or lexical databases. They are conceived
Technology,vocabulariesarealsocalledcomputationallexiconsorlexicaldatabases. Theyareconceived
as databases and lexical knowledge bases designed for automatic processing of natural languages
asdatabasesandlexicalknowledgebasesdesignedforautomaticprocessingofnaturallanguages[32].
[32]. In these vocabularies, lexical knowledge—at the phonetic and phonological, morphological,
Inthesevocabularies,lexicalknowledge—atthephoneticandphonological,morphological,syntactic,
syntactic, semantic, pragmatic, discourse, and world levels—becomes explicit and is organized with
semantic, pragmatic, discourse, and world levels—becomes explicit and is organized with formal
formal data models that are suitable for automatic natural language processing [33–35]. A widely
data models that are suitable for automatic natural language processing [33–35]. A widely used
used example of a computational lexicon is WordNet [17]. Vocabularies constitute a basic
exampleofacomputationallexiconisWordNet[17]. Vocabulariesconstituteabasiccomponentin
component in the architecture of Natural Language Processing Systems: they are necessary for the
thearchitectureofNaturalLanguageProcessingSystems: theyarenecessaryforthedevelopmentof
development of linguistic applications such as spelling and style correctors, retrieval of textual
linguisticapplicationssuchasspellingandstylecorrectors,retrievaloftextualinformation,andthe
information, and the indexing and description of documents and textual resources. Two sources of
indexinganddescriptionofdocumentsandtextualresources. Twosourcesofcomputationallexicon
computational lexicon distribution are, for example, the European agency ELRA [36] and the US
distributionare,forexample,theEuropeanagencyELRA[36]andtheUSconsortiumLDC[37].
consortium LDC [37].
Finally, in the field of e-learning, vocabularies are a mechanism for semantic representation
Finally, in the field of e-learning, vocabularies are a mechanism for semantic representation that
that allows human agents or software to locate, interpret, and retrieve educational content or to
allows human agents or software to locate, interpret, and retrieve educational content or to process it
processitfordidacticpurposes. Vocabulariesarecurrentlymainlyappliedtosolvetwoquestions:
for didactic purposes. Vocabularies are currently mainly applied to solve two questions: (1) the
(1) the representation and retrieval of digital educational resources; and (2) the interoperability
representation and retrieval of digital educational resources; and (2) the interoperability between
between e-learning tools and content [9,10,38]. In the former case, the main type of vocabularies
e-learning tools and content [9,10,38]. In the former case, the main type of vocabularies used are
used are taxonomies and thesauri [10], that is, vocabularies of terms organized into categories
taxonomies and thesauri [10], that is, vocabularies of terms organized into categories and/or
and/or interconnected by hypernymy–hyponymy and other semantic relations. In the latter case,
interconnected by hypernymy–hyponymy and other semantic relations. In the latter case, the type of
thetypeofvocabulariesusedarethesauriandontologiesthatconceptuallyrepresentthedimensions
vocabularies used are thesauri and ontologies that conceptually represent the dimensions of an
ofane-learningsystem: theagents,tools,domainofknowledge,methodologies,andteachingmodels,
e-learning system: the agents, tools, domain of knowledge, methodologies, and teaching models, etc.
etc.[39]. Inthefollowingsections,vocabularytypesandexamplesofeachofthesetypeswillbeseen.
[39]. In the following sections, vocabulary types and examples of each of these types will be seen.
Educ.Sci.2017,7,33 4of38
Educ. Sci. 2017, 7, 33 4 of 39
33.. WWhhaatt aa VVooccaabbuullaarryy IIss LLiikkee
AA vvooccaabbuullaarryy,, iinn aannyy ooff iittss iinntteerrpprreettaattiioonnss,, ccoommpprriisseess aatt lleeaasstt aa lleexxiiccaall uunniitt wwhhiicchh ccaann bbee ggeenneerraall
oorr ssppeecciifificc ttoo aa ddoommaaiinn [[4400]].. TThhee wwoorrddss oorr wwoorrdd ggrroouuppss tthhaatt ccoonnssttiittuuttee iitt aarree pprreesseenntteedd iinn aa ssttaannddaarrdd
ffoorrmm ((ii..ee..,, ccaannoonniiccaall ffoorrmm)) iiff tthheeyy aarree iinnfflleecctteedd wwoorrddss aanndd ccaann bbee oorrggaanniizzeedd iinnttoo ccllaasssseess oorr ccaatteeggoorriieess..
TThhee oovveerraallll oorrggaanniizzaattiioonn ooff tthhee vvooccaabbuullaarryy iiss ccaalllleedd iittss mmaaccrroossttrruuccttuurree.. TThhee ddeessccrriippttiioonn ooff eeaacchh wwoorrdd
iiss ggiivveenn iinn wwhhaatt iiss kknnoowwnn aass aann eennttrryy ((FFiigguurreess 11 aanndd 22)).. TThhee ccoonntteennttss ooff eennttrriieess,, kknnoowwnn aass tthheeiirr
mmiiccrroossttrruuccttuurree,, ddeeppeenndd oonn tthhee ppuurrppoossee ooff tthhee vvooccaabbuullaarryy [[4411]] bbuutt ccaann iinncclluuddee,, iinn aaddddiittiioonn ttoo tthheeiirr
mmeeaanniinnggss,, ggrraammmmaattiiccaall,, uussaaggee,, pphhoonneettiicc,, aanndd eettyymmoollooggiiccaall iinnffoorrmmaattiioonn,, aanndd rreellaattiioonnss wwiitthh ootthheerr
vvooccaabbuullaarryy tteerrmmss..

FFiigguurree 22.. LLeexxiiccaall eennttrryy ooff tthhee wwoorrdd ““lleessssoonn”” iinn WWoorrddNNeett..
Several types of vocabulary, on the one hand, can be distinguished concerning macrostructure
Severaltypesofvocabulary,ontheonehand,canbedistinguishedconcerningmacrostructure
and microstructure [9]: (i) lists of terms; (ii) glossaries; (iii) classifications and taxonomies;
andmicrostructure[9]: (i)listsofterms;(ii)glossaries;(iii)classificationsandtaxonomies;(iv)thesauri;
(iv) thesauri; (v) ontologies; (vi) dictionaries; and (vii) lexicons [10]. In Section 6, the way in which
(v)ontologies;(vi)dictionaries;and(vii)lexicons[10]. InSection6,thewayinwhicheachofthese
each of these vocabulary types is configured will be shown in more detail, as well as some examples
vocabularytypesisconfiguredwillbeshowninmoredetail,aswellassomeexamplesusedinthe
used in the retrieval of digital educational resources.
retrievalofdigitaleducationalresources.
On the other hand, based on the procedural criterion of the output of a lookup strategy using
Ontheotherhand,basedontheproceduralcriterionoftheoutputofalookupstrategyusing
vocabularies, two fundamental vocabulary types can be considered [40]:
vocabularies,twofundamentalvocabularytypescanbeconsidered[40]:
• Semasiological vocabulary: the lookup key is the word (form) and the information required is
• Semasiologicalvocabulary: thelookupkeyistheword(form)andtheinformationrequiredis
semantic. Usually different meanings of a word can be considered as well as interrelations
semantic.Usuallydifferentmeaningsofawordcanbeconsideredaswellasinterrelations(mainly
(mainly semantic) between words.
semantic)betweenwords.
• Onomasiological vocabulary: the lookup key is a concept and the information required is the
• Onomasiologicalvocabulary: thelookupkeyisaconceptandtheinformationrequiredisthe
word form or, more precisely, the term that designates the concept (and, if necessary, different
wordformor,moreprecisely,thetermthatdesignatestheconcept(and,ifnecessary,different
terms correlated with it).
termscorrelatedwithit).
On that bases, this section and the rest of the article are mainly following a semasiological
approOancht,h aaltthboausgesh, wthitishosuect tiigonnorainndg tthhee orneostmoafsitohleogairctaicl laenagrlee. mIna tihnilsy rfeoslploecwt,i nthge atesremm “atseiromlo”g wicialll
abpe pursoeadc hto, adltehnoouteg ha wwiothrdo uthtaigt niso raisnsgigtnheedo ntoo ma caosinocleopgti cuasleadn ginle s.pInectihails larensgpueacgt,etsh tehtaetr mocc“uterr “m…” wini lal
bdeomusaeidn otor dsuebnjoetcet, aanwdo rcdhatrhaactteisriazsesdig bnye tdheto uasec oonf cseppetciufisce ldinignusipsteicci amlelaanngs uoaf geexsprthesastiooncc…ur” “[4.2.].. i n
adomainorsubject,andcharacterizedbytheuseofspecificlinguisticmeansofexpression... ”[42].
AA vvooccaabbuullaarryy ccaann aallssoo bbee ccoonncceeiivveedd aass aann iinnddeexx tthhaatt eessttaabblliisshheess aa ccoorrrreessppoonnddeennccee bbeettwweeeenn tthhee
oorrtthhooggrraapphhiicc ffoorrmm ooff aa wwoorrdd aanndd tthhee iinnffoorrmmaattioionn aabboouut tththaat twwoordrd [4[400].] .HHowoweveevre, ri,t imt maya ynonto bteb ea
aonoen-teo-t-oo-noen ceocrorersrepsopnodnednecne,c ea,s aisn itnhothseo sceasceass eins iwnhwichhi cah waowrdo rhdash adsifdfeirffeenrte nsytnstyancttaicc tciactceagtoergieosr,i eins,
ihnohmoomgoragprahpsh, as,nadn idn ipnoplyoslyesmemy,y a, asisnignlgel ewworodrd foformrm cacann hhaavvee ddififffeerreenntt eennttrriieess.. TThhiiss wwoouulldd bbee mmaaiinnllyy
tthhee ccaassee ooff ddiiccttiioonnaarriieessa annddl elexxicicoonnss..I nIno oththeerrc acsaesse,sa, ab ibuinuinviovcoaclawl worodr-din-ifnofromrmataiotinocno crorersrpesopnodnednecnecies
nise nceescseassrya,rya,s aisn icno ncotnrotlrloeldlevdo vcoacbaubluarlaiersiefso froIrR IRa nanddr ertertireivevaallo offd digigitiatallo obbjejeccttss.. CCoonnttrroolllleedd vvooccaabbuullaarriieess
try to ensure a biunivocal correspondence by a control process that disambiguates homograph terms
using qualifiers to specify, in the case of synonymy, a single term as the preferred term, also known
Educ.Sci.2017,7,33 5of38
tEErddyuucct..o SScceii.n. 22s00u117r7e,, 77a,, 33b33 i u nivocalcorrespondencebyacontrolprocessthatdisambiguateshomographt55e roomff 33s99
usingqualifierstospecify,inthecaseofsynonymy,asingletermasthepreferredterm,alsoknown
aaasss ttthhheee dddeeessscccrrriiippptttooorrr (((FFFiiiggguuurrreee 333))),,, aaannnddd,,, iiinnn ttthhheee cccaaassseee ooofff pppooollyylyssseeemmmooouuusss tteeterrmmrmss,,s ,bbbyyy rreerssettsrrtiirccittciitnningg gmmmeeaaennaiinnniggn gtthhtrrhooruuogguhhg haa
addoodmmomaaiianni nnnoonttoeet e[[99[]]9.. ].

FFFiiiggguuurrreee 333... QQQuuuaaallliiifffiiieeerrrsss,,, iiinnn pppaaarrreeennnttthhheeessseeesss,,, tttooo dddiiissstttiiinnnggguuuiiissshhh hhhooommmooogggrrraaappphhhsss (((sssooouuurrrccceee::: [[[999]]])))...
TThhee mmeeaanniinngg ooff aa lleexxiiccaall eennttrryy iiss eexxpprreesssseedd iinn iittss ddeeffiinniittiioonn.. AA ddeeffiinniittiioonn iiss ““aa ddeessccrriippttiivvee
The meaning of a lexical entry is expressed in its definition. A definition is “a descriptive
rreepprreesseennttaattiioonn ooff aa ccoonncceepptt wwhhiicchh sseerrvveess ttoo ddiiffffeerreennttiiaattee iitt ffrroomm rreellaatteedd ccoonncceeppttss”” [[2299]].. TThhee
representationofaconceptwhichservestodifferentiateitfromrelatedconcepts”[29]. Thedefinition
ddeeffiinniittiioonn ccaann ttaakkee mmaannyy ffoorrmmss,, ffrroomm aa ssiimmppllee ssttaatteemmeenntt ttoo rreeffeerreenncceess bbaasseedd oonn tthhee eessttaabblliisshhmmeenntt ooff
cantakemanyforms,fromasimplestatementtoreferencesbasedontheestablishmentofsemantic
sseemmaannttiicc rreellaattiioonnss bbeettwweeeenn tthhee lleexxiiccaall uunniittss ((oorr tteerrmmss iinn ssppeecciiffiicc llaanngguuaaggeess)) iinn tthhee vvooccaabbuullaarryy.. TThhiiss
relations between the lexical units (or terms in specific languages) in the vocabulary. This latter
llaatttteerr aapppprrooaacchh——tthhee ddeeffiinniittiioonn ooff mmeeaanniinngg bbaasseedd oonn sseemmaannttiicc rreellaattiioonnss——iiss pprreeffeerrrreedd iinn vvooccaabbuullaarriieess
approach—thedefinitionofmeaningbasedonsemanticrelations—ispreferredinvocabulariesaimed
aaiimmeedd aatt iinnffoorrmmaattiioonn rreettrriieevvaall ((IIRR)) ((FFiigguurree 44))..
atinformationretrieval(IR)(Figure4).

Figure 4. Definition based on semantic relations (source: European Education Thesaurus
FFiigguurree 44.. DDeeffiinniittiioonn bbaasseedd oonn sseemmaannttiicc rreellaattiioonnss ((ssoouurrccee:: EEuurrooppeeaann EEdduuccaattiioonn TThheessaauurruuss
http://vocabularyserver.com/tee/en/index.php).
hhttttpp::////vvooccaabbuullaarryysseerrvveerr..ccoomm//tteeee//eenn//iinnddeexx..pphhpp))..
CCClllaaassssssiiiccc lexlleeixcxaiicclaarlle lartrieeollnaattsiioobnnetssw ebbeeenttwwweeoeernnd mwweaoonrrddin gmmsaeeraaenneiinnqggussi vaaalrreeen ceee,qqouupiivvpaaollseeinnticcoeen,,, inoocpplppuosoissoiinttii,oocnno,,- hiiynnpccolluunssyiimoonny,,,
accnoo-d-hhpyyapprootn–nayylmml[yy1,,3 aa].nnTddh ppeaamrrtte––aaanlllli n[[11g33e]]..q TTuhhiveea mmleneeaacnneiirnneggla eetiqqouuniivvisaaslleeynnnccoeen yrrmeellyaa.ttiiToownn oiisso ssryymnnooonnryyemmwyyo.. rTTdwwsooa rooerrs mmynooorrnee ywwmooorruddsss
iaafrrteeh sseyyynncooannnyybmmeooruuepss liiaff cttehhdeeyyin ccaaannn y bbeceo rrneetppellxaatcceweddi tiihnno aaunntyyc hccaoonnngtteeinxxgtt wwmiietthhaonouuinttg cc.hhTaahnniggsiincnoggn mmdieetaaionnniinnoggf.. eTTqhhuiiass l ccitooynniddniittaiiloolnnth ooeff
meeqqeuuaaanlliiinttyyg siinno aafllall ttwhheeo rmmdeeeaaxnnpiinnlaggissn sooffw aah wwyooarrbdds oeelxxupptlleaaiisnnyssn wwonhhyyym aasbbssaoorlleuusttecea ssryycnneooannnyydmm,fsso aarrrpee rssacccaatrriccceea laapnnuddr,, pffooorrs eppsrr,aaaccttliieccsaasll
spptuurirrcpptoodsseeefiss,,n iaat iolleenssssi ssspttrrriieccftte rddreeeffdiinn,iisttoiiootnnh aiitss tppwrroeeffoeerrrrrmeeddo,,r essoow ttohhraadtts ttawwreoo sooyrrn ommnooyrrmee owwuoosrrwddssit haarrreee ssspyyenncootnntoyymmaoomuuessa nwwiniittghh
irrfeetsshppeeeyccttc ttaoon aab mmeeeeaaxnnchiinnaggn giiffe ttdhheeinyy tcchaaannt bbseep eeecxxiccfihhcaancnoggneetdde xiinnt. ttFhhiaagttu ssrppeee2cciiffsiihcc o ccwoonnsttteehxxett.. sFFyiinggouunrreey m22 ssehhxooawwmssp ttlhheee, dssyyennteoornnreyynmmt
eeexxxaaammmpppllleee,,, lddeeesttseeorrnrr,eenanntt deexxoaabmmjeppcllteel,,e llseesssossnoonnw,, aiatnnhddr eoosbbpjjeeecccttt llteeossssthooenn swweciittohhn rrdeessmppeeeaccntt titnoo g tthhoeef ssaeelcceoosnnsoddn mm. eeaanniinngg ooff aa lleessssoonn..
TThhee ooppppoossiittee rreellaattiioonn ttoo ssyynnoonnyymmyy iiss aannttoonnyymmyy ((FFiigguurree 55)).. IInn tthhee lleexxiiccooggrraapphhiicc ttrraaddiittiioonn,,
aannttoonnyymmss aarree ddeeffiinneedd aass wwoorrddss wwiitthh ooppppoossiittee mmeeaanniinnggss aanndd,, aass ssuucchh,, aass ooppppoosseedd ttoo ssyynnoonnyymmss..
HHoowweevveerr,, tthhiiss ddeeffiinniittiioonn ooff aannttoonnyymmyy iiss ttoooo vvaagguuee.. IInn [[4433]],, tthhee nnoottiioonn iiss rreeffiinneedd,, ttaakkiinngg iinnttoo aaccccoouunntt
tthhee ffaacctt tthhaatt aannttoonnyymmyy eennttaaiillss ssiimmiillaarriittyy bbeettwweeeenn tthhee tteerrmmss.. AAnnttoonnyymmoouuss tteerrmmss aarree aallwwaayyss
Educ.Sci.2017,7,33 6of38
Theoppositerelationtosynonymyisantonymy(Figure5).Inthelexicographictradition,antonyms
aErdeucd. Secfii. n20e1d7, a7,s 33w ords with opposite meanings and, as such, as opposed to synonyms. How6e ovfe 3r9,
thisdefinitionofantonymyistoovague. In[43],thenotionisrefined,takingintoaccountthefactthat
composed by common semes, i.e., semantic features: thus, brother and sister share the semes
antonymyentailssimilaritybetweentheterms. Antonymoustermsarealwayscomposedbycommon
/human being/ and /born from the same parents/, and are opposed by the seme /pertaining to sex/.
semes,i.e.,semanticfeatures: thus,brotherandsistersharethesemes/humanbeing/and/bornfrom
Consequently, the antonymy relation can be defined as the relation that binds two words in the same
thesameparents/,andareopposedbytheseme/pertainingtosex/. Consequently,theantonymy
grammatical category that share part of their semes and that have an opposing counterpart.
relationcanbedefinedastherelationthatbindstwowordsinthesamegrammaticalcategorythat
Antonymy is also composed of different types of oppositions, mainly binary ones. Three types of
share part of their semes and that have an opposing counterpart. Antonymy is also composed of
antonyms are usually distinguished: (1) Contradictory or complementary antonyms, which express
differenttypesofoppositions,mainlybinaryones. Threetypesofantonymsareusuallydistinguished:
an exclusive disjunction relation, that is, the negation of either one of the words implies the
(1)Contradictoryorcomplementaryantonyms,whichexpressanexclusivedisjunctionrelation,thatis,
affirmation of the other one and the two terms cannot be simultaneously denied, e.g., man/woman,
thenegationofeitheroneofthewordsimpliestheaffirmationoftheotheroneandthetwoterms
present/past. (2) Contrary or gradable antonyms, which define the poles in an implicit gradation
cannotbesimultaneouslydenied,e.g.,man/woman,present/past. (2)Contraryorgradableantonyms,
scale and allow the existence of intermediate degrees. Big/small, heat/cold, love/hatred.
whichdefinethepolesinanimplicitgradationscaleandallowtheexistenceofintermediatedegrees.
(3) Reciprocal antonyms are those that force the replacement of one by the other in a given statement
Big/small,heat/cold,love/hatred. (3)Reciprocalantonymsarethosethatforcethereplacementof
to preserve the relation, e.g., doctor/patient, parent/child.
onebytheotherinagivenstatementtopreservetherelation,e.g.,doctor/patient,parent/child.

FFiigguurree 5.A5n. tonyAmnstoonfytmhes worodf “leatrhne” (Sowuorcred: The“slaeuarrnu”s. com(Swouebrcseit:e httTph:/es/awuwruws..cthoemsa uruws.ecbosmit/e
bhrtotpw:/s/ew/wlewar.nth/e).saurus.com/browse/learn/).
TThhee mmaianinin cilnucsliuosniorenl atrieolnatiisogne nise ragleiznaetrioanlizoarthioynp eronry mhyy,paenrndyimtsyi,n vaenrdse rietsla tiinovneirsssep erceilaaltizioanti oins
osprehcyipaolinzyamtiyo.nA onr ehxyapmonpylmeyo. fAhny peexranmymplye –ohfy hpyopneyrmnyymreyl–ahtiyopnosniysmshyo wrenlaitnioFnisg iusr esh4o.wThne inh yFpigeurnrye m4.
aTphpee hayrspemrnayrkme dapapsetahres Bmroarakdeedr aTse rtmhe (BBrTo)a,daenrd Ttehremh (yBpTo),n aynmds tharee hmypaorkneydmass aNrea mrraorwkeTde rams Ns(aNrrTosw).
HTeyrpmersn (yNmTys–).h yHpyopneyrmnyymreyl–ahtiyopnosnayremays yrmelmatieotrnisc aanred atrsaynmsimtiveetrisco athnedy t“raarnrsaintigvee” swoo trhdesyi n“taorsriamngpele”
owromrdusl tiinptloe hsiimerpalrec hoire smfuroltmiplme ohrieergaerncherieasl tforommo mreosrpee gciefincermale aton imngosr.eS stprueccitfuicre msaeraeniunsgusa. lSlytrluactttiucreess,
bauret tuhseutaelrlmy lhaitetricaercsh, ybuist utsheed tteormem hpihearasirzcehyth eisc uonsecdep ttou aelmdeppheansdizeen ctheeo fchoynpceopntyumals doenpheynpdeernncyem osf.
hypoCnoy-mhys poonn hyympyerwnyitmhisn. thesamehierarchyisestablishedbetweenthewordsrelatedtothesame
hyperCoon-yhmypy,oen.gy.m,iyn Fwigituhrien 4t,h“ea sltaemrnea htiiveerasrcchhoyo li”s aensdta“bbliosahreddi nbgetswcheoeonl ”thaer ewcoor-hdys proenlaytmeds toof t“hsech soaoml”e.
Chyo-pheyrpononyymmys, aer.ge.d, iisnt inFgiguuisrhee d4, b“yaoltneernoartimveo rsecdheoloiml”i tainngd c“hbaoraacrtdeirnisgt icssc.hAoodl”e liamrei ticnog-hcyhparoancytemriss toicf
i“sscah“onoel”c.e sCsoa-rhyycphoanryamctes raisrtei cdtihstaitngduisitsihnegdu ibsyh eosnae coor nmceoprte fdroelmimrietilnatge dchcaornaccteeprtisst”ic[s2.9 A]. dUenlilmikietining
acnhtaornayctmeryisbtiacs eisd ao n“naebceinssaarryyo cphpaorsaictitoerni,stthice tnheagt adtiisotninogfuoinsheeosf at hceoncoc-ehpyt pforonmym resldatoeeds ncoontcneepctess”s a[r2i9ly].
iUmnplliyket hine aafnfitromnyatmioyn boafstehde oonth ae rbcinoa-hryy poopnpyomsi,tibount, tthhee cnheogicaetiorenm oafi nonseo poef nth:eif cxoi-shnyoptoannym“asl tderoneast nivoet
sncehcoeossl”a,riiltyc aimnpbley ath“eb aofafridrminagtisocnh oofo tl”heo ortah“edr acon-chinygposnchyomo,l ”b.uCt toh-eh ychpooincye mresmaarienms ouptuenal: liyf xe xisc lnuosti vaen:
a“a“lstechrnoaotli”veis sacnho“oallt”e, rnita tciavne sbceh oao l“”boorarad“inboga rsdchinogols”c hooro la” o“draan“cdinagn csinchgosoclh”.o oCl”o,-heytcp.oMnyomreso vaerre,
cmo-uhtyupalolny yemxcslcuasnivhea: vae “syscnhoonoylm” yiso arna n“taolnteyrmnaytirveela tsicohnosobl”e twore ean “ebaocharodtihnegr .sFcohroeoxl”a mopr lae ,““dcoalnlecgineg”
asnchdo“ouln”,i veetrcs.i tMy”ocraenovbeerr, ecgoa-rhdyepdoansycmo-sh ycpaonn yhmavseo fsy“sncohnoyoml”ya nodr caanntopnasysmfoyr sryelnaotinoynms sb;ecotwntereanri weaisceh,
other. For example, “college” and “university” can be regarded as co-hyponyms of “school” and can
“virtuallearning”and“face-to-facelearning”,co-hyponymsof“learning”,areantonymous[43].
pass Tfhoer psyanrto-anlylmors;h ocloonntyrmaryi/wmiesreo, n“yvmiryturealla lteioanrniisnagl”s oaandh ie“rfaacrceh-tioc-afla,caen tleisayrmnimnge”t,r icco,-ahnydptornaynmsitsi voef
“learning”, are antonymous [43].
relation in which one of the terms denotes a part and the other the whole pertaining to that part
The part-all or holonymy/meronymy relation is also a hierarchical, antisymmetric, and transitive
(Figure6). Thedifferencewithrespecttothehyponymy–hypernymyrelationisthatitisarelationof
relation in which one of the terms denotes a part and the other the whole pertaining to that part
belongingratherthaninclusion,someronymsdonotinheritthehomonyms’attributes. Meronymic
(Figure 6). The difference with respect to the hyponymy–hypernymy relation is that it is a relation of
dependencerelationsarevariedandcomplex: member/set(teacher/faculty),component/assembly
belonging rather than inclusion, so meronyms do not inherit the homonyms’ attributes. Meronymic
dependence relations are varied and complex: member/set (teacher/faculty), component/assembly
(leg/chair), portion/mass (slice/cake), material/object (steel/bicycle) [43]. In the WordNet vocabulary,
three types of holonymic relations are used: member, substance, and part [14].
Educ.Sci.2017,7,33 7of38
(leg/chair),portion/mass(slice/cake),material/object(steel/bicycle)[43]. IntheWordNetvocabulary,
threetypesofholonymicrelationsareused: member,substance,andpart[14].
Educ. Sci. 2017, 7, 33 7 of 39

FFiigguurree 66.. MMeerroonnyymmss aanndd hhoololonnyymmss wwitihth rreessppeecctt ttoo tthhee sseeccoonndd mmeeaanniinngg ooff ““sscchhooooll”” ((ssoouurrccee::
WWoorrddNNeett [[1177]]))..
In addition to “classic” lexical relations, vocabularies can include many other semantic
Inadditionto“classic”lexicalrelations,vocabulariescanincludemanyothersemanticassociative
associative relations, such as family (fire/fireman), agent (student/learning agent), instrument
relations,suchasfamily(fire/fireman),agent(student/learningagent),instrument(exercise/practice
(exercise/practice instrument), or location (school/student location).
instrument),orlocation(school/studentlocation).
As will be seen in the following sections, semantic relations, particularly those of synonymy
As will be seen in the following sections, semantic relations, particularly those of synonymy
and hyponymy–hypernymy, are basic for building vocabularies for the classification and indexing
andhyponymy–hypernymy,arebasicforbuildingvocabulariesfortheclassificationandindexingof
of information and of digital educational resources.
informationandofdigitaleducationalresources.
4. How Vocabularies Work in Information Retrieval
4. HowVocabulariesWorkinInformationRetrieval
Information retrieval (IR) is a field of Artificial Intelligence whose object is the search for
Information retrieval (IR) is a field of Artificial Intelligence whose object is the search for
information in documents, document search, the search for metadata that describe documents, and
informationindocuments,documentsearch,thesearchformetadatathatdescribedocuments,andthe
the search for data in databases, be it via the Internet, an intranet, for texts, images, sound, or other
searchfordataindatabases,beitviatheInternet,anintranet,fortexts,images,sound,orotherdata,
data, in a pertinent and relevant manner [15]. Retrieval of digital educational resources is thus a
inapertinentandrelevantmanner[15]. Retrievalofdigitaleducationalresourcesisthusaparticular
particular case of IR. In this section, the basic IR mechanisms that are also shared by retrieval of digital
caseofIR.Inthissection,thebasicIRmechanismsthatarealsosharedbyretrievalofdigitaleducational
educational resources are reviewed.
resourcesarereviewed.
In the context of IR, vocabularies are information organization systems whose purpose is to
InthecontextofIR,vocabulariesareinformationorganizationsystemswhosepurposeistoincrease
increase the effectiveness of the processes of indexing, search, or navigation of collections of digital
theeffectivenessoftheprocessesofindexing,search,ornavigationofcollectionsofdigitalresources
resources with informational content (hereinafter, simply resources). They constitute a “bridge”
with informational content (hereinafter, simply resources). They constitute a “bridge” between
between information representation at a high level of abstraction and representation at the level of
informationrepresentationatahighlevelofabstractionandrepresentationatthelevelofcomputer
computer information system, as well as between the natural language in which people make a
informationsystem,aswellasbetweenthenaturallanguageinwhichpeoplemakeasearchqueryand
search query and the formal query languages used by machines [8,10,16]. The idea is to use the terms
theformalquerylanguagesusedbymachines[8,10,16]. Theideaistousethetermstorepresentthe
to represent the contents of resources and relations between the terms in the vocabularies to improve
contentsofresourcesandrelationsbetweenthetermsinthevocabulariestoimprovetheexhaustiveness
the exhaustiveness and precision of the indexing results and the search for resources, as well as the
and precision of the indexing results and the search for resources, as well as the usability of the
usability of the user interface.
userinterface.
In this regard, exhaustiveness in search processes improves if the terms employed by the user in
Inthisregard,exhaustivenessinsearchprocessesimprovesifthetermsemployedbytheuserin
their request (i.e., “dog”) are expanded by using all the possible terms related either
theirrequest(i.e.,“dog”)areexpandedbyusingallthepossibletermsrelatedeitherorthographically
orthographically (i.e., “dog”, “doggie”), in what is known as the form control, or else by their
(i.e.,“dog”,“doggie”),inwhatisknownastheformcontrol,orelsebytheirmeaning,throughsynonym
meaning, through synonym control (e.g., “pooch”, “canine”, “cur”), quasi-synonyms,
control(e.g.,“pooch”,“canine”,“cur”),quasi-synonyms,hyponyms/hypernyms(e.g.,“quadruped”,
hyponyms/hypernyms (e.g., “quadruped”, holonyms/meronyms (e.g., “pack”) and other associated
holonyms/meronyms (e.g., “pack”) and other associated terms. Regarding the improvement in
terms. Regarding the improvement in precision, vocabularies make it possible to combine terms to
precision, vocabularies make it possible to combine terms to fine-tune the user’s query, what is
fine-tune the user’s query, what is known as coordination. They make it possible to distinguish
knownascoordination. Theymakeitpossibletodistinguishbetweenhomographs,usedefinitionsto
between homographs, use definitions to disambiguate, restrict, or clarify the meanings of the query,
disambiguate,restrict,orclarifythemeaningsofthequery,andthefrequencyofuseofthetermsto
and the frequency of use of the terms to statistically differentiate the most likely terms on the basis of
statisticallydifferentiatethemostlikelytermsonthebasisofuse,context,orevenuserprofile. Finally,
use, context, or even user profile. Finally, as regards interface usability, vocabularies offer users an
asregardsinterfaceusability,vocabulariesofferusersanalternativesystemforaccesstoresourcesas
alternative system for access to resources as a terminological-conceptual map of the resource
aterminological-conceptualmapoftheresourcecollections(Figure7).
collections (Figure 7).
Educ. Sci. 2017, 7, 33 8 of 39
Educ.Sci.2017,7,33 8of38
Educ. Sci. 2017, 7, 33 8 of 39

Figure 7. Vocabulary for navigation in the archeological digital repository Coclé in Panama (source:
FFhiitggtupu:rr/ee/o 77d.. aVV-fooecccaa.obbruuglla/acrroyyc flfeoo/rr) .nn aavviiggaattiioonn iinn tthhee aarrcchheeoollooggiiccaall ddiiggiittaall rreeppoossiittoorryy CCoocclléé iinn PPaannaammaa ((ssoouurrccee: :
hhttttpp::///o/doad-afe-fce.oc.rogr/gc/occloec/l)e. /).
The functioning of vocabularies in the indexing, search, and navigation of resources are
discuTTshhseee dffu uinnnc cmttiiooonrneiin ndggeo tafoivfl oivncoa tbchauebl anureliaxertsi teiwns otih nse uitbnhsdeee cxitniinodnge,sx.si en agr,c hs,eaanrcdhn, aavnigda tnioanviogfarteiosonu rocfe sreasroeudricsecsu sasered
discussed in more detail in the next two subsections.
inmoredetailinthenexttwosubsections.
4.1. Vocabulary in Resource Indexing
44..11.. VVooccaabbuullaarryy iinn RReessoouurrccee IInnddeexxiinngg
The first process for IR is resource indexing. In indexing, resources are represented by means of
termTTs hhaeen fdfiir rtsshtt epp rirnoocdceeiscsses sff ootrhr aIIRtR liiissn krree sstoeourumrrccsee iiannndddeex xriinensggo.. uIInrnc ieinnsd daeerxxeii nncgrg,e, arreteessdoou u(rFrcciegesus araerre e8 r)re.e ppArr eesssmeennattlele,dd l ibbmyy imtmedeea asnnesst ooofff
ttteeerrrmmmsss aatnhndadt t thrheeep irninedsdiecinceets stt hhthea tactlo inlnikntektne ttrsem romsf astn haden rrdee ssrooeuusrorcuceers ciaesrs es aeclrreeec atcterededa at(enFdidg (uaFrsiesgo8uc)ri.eaA t8e)ds.m Awa iltsl,hml itamhllii,st e lrdiemssioettuedorcf est.ee trT mohfes
ttteherrammtsrs e tphmraeats yre encptormtehseee ncftor onthmtee ncato snpotrfeent-hetsxe iorseft isntohgue rcrcoeesnoitsruosrelclleee dcis te vsdoelcaeancbtduedlaa srasyno,dc ia aantsedsd oicwti aiittseh dtth hweinsit hrte etsrhomiuser rcdee s.aoTsushrigceent.me Tremhnest
tmienradmyesxc ionmmga ebyy fr caoosmmsigea npfarrtoeiom-en x; aios ttphinreegr-wecoxisinestt,r iinot lgcl eacdno vbneotr ceoaxlblteruadlca trveyod,c afarnbodumliat wriysi,tt hhaiennn dth teietr rmeisse odtuharescnse isgt tenhrmmemeendste liavnsedssie,g xwninmhgaetbn iyts
iaknsndsoeigwxninna gti aobsny ; aeoxststhrigaencrwtaitoiisnoe n,;ii notdtcheaexnrinwbgei see[x,8 ti]rt. a ccTatnhe deb efir enoxdmterxaw ctigethedni nferrotahmtee dwre istcohouiunrlc dteh sebt rehe esmuosuseredclve, se istfh, wesmoh sawetlivissehkse,n dwo, whaanst aisas
ketenxrtomrwaicnnt ioolanosg iniecdxaetlr xmaicnatgpio [fn8o ]r.i unTdsheeerxsiin ntdoge exx[8gp]el.o nreTerh aaetne ddin rcdeoteurxile dvgbeee nthueersa ectdoe,ldlie fccstooiouwnld irs ehsbeoedu ,ruacsseesad (t,F eirigmfu irsneoo 7l)ow.g iischaeldm, aaps foar
tuesremrsiInntoodloeexxgpiinclaoglr emisa anpbda fsorierct aurlisleyev resc atthorre eiecxdopl lloeorcuetti oainnnd r etrsheorterueire cvsetesa gt(heFsei:g cu(o1rle)l e7ca)tn.ioalny rseiss ooufr ctehse ( Fdigoumraei n7) . (collection of
resouIInnrcddeeesxx)i,in nwggh iiisscb hab esanisctiaaclaillylsl yct hacrera ierexrditerodauc ttoiiounnt t hoinrfe tehtshetr aekgeee sys: tta(e1gr)emsa:n s a(i1lny) seiaasncohafl yothsf ietsh deoo frm etashoineu r(dccoeolsml;e (ac2tini)o tnh(ceoo fslelreelecstcoituoionrcn e osof)f ,
rwtehsheoi cumhrcoeesnst) t,ar weilpshrtiehcshee neetnxatttariavilcest ittohener meoxfst trohafec takio ecnyo onteft rrtmohlelse kidne yve oateccrhambousf liatnhr yee artceohs odouef rstcchereisb ;ree( 2sto)hutehr cereessse;o l(ue2cr)tc iteohsne; soaenfldethc te(i3om)n to ohsfet
trcherepe armetisooensnt t oarfte ipvderaettsaee rnsmttrasutoicvftuea rteceosr nm(tcrsao llloleefd d aiv ncodocinactbersuo)ll alterody stvtooodrceea sbtchureliab areysts hoteoci radetseioosnucrsric bbeese ;ttwahneed ern(e3 sr)oetushorecuecrsrce;e asat niaodnn d(o 3ft)e drtamhteas
cs(rFteriuagtcuitoruenr e8os).f ( c daalltead sitnrudcictuesr)esto (csatollreedt hinedaiscseosc)i attoi osntosrbee ttwhee eanssroecsioautirocness abnedtwteeremn sr(eFsioguurrcee8s ).and terms
(Figure 8).

FFiigguurree 88.. IInnddeexxiinngg ooff ddiiggiittaall rreessoouurrcceess wwiitthh vvooccaabbuullaarriieess..
Figure 8. Indexing of digital resources with vocabularies.
The indexing process can be manual, automatic, or semiautomatic [2]. In the first case, an expert (or
Theindexingprocesscanbemanual,automatic,orsemiautomatic[2]. Inthefirstcase,anexpert
expeTrth ceo imndmexititnege) p arnoacleyszse csa tnh be ec omnatneunatsl,, acuotnotmexatti,c a, nodr ssetmruiacututorme aotfi ce a[2c]h. Irne stohue rfcires at ncads aes, saing nesx ptoe ritt (tohre
(orexpertcommittee)analyzesthecontents,context,andstructureofeachresourceandassignsto
esxept eorft ctoermmms itftreoem) a na aclyoznetrso tlhleed c ovnotceanbtsu,l caoryn tethxat,t abneds ts tdruecstcurirbee os f ieta (ccha treegsoourirzcaet iaonnd bayss iagsnsisg tnom ite tnhte).
itthesetoftermsfromacontrolledvocabularythatbestdescribesit(categorizationbyassignment).
sAetn ootfh eterr mopst iforno min at hciso nfitrrsotl lceads ev oisc athbue leaxrytr atchtaiot nb eosft tdhee stcerribmess tiht a(tc aatreeg moroizsat trioepnr ebsye natsastiigvnem oef ntth)e.
Another option in this first case is the extraction of the terms that are most representative of the
Educ.Sci.2017,7,33 9of38
Educ. Sci. 2017, 7, 33 9 of 39
Another option in this first case is the extraction of the terms that are most representative of the
rreessoouurrccee oorri tistsm metaedtaadtaat(ac a(tceagtoergiozraitzioatniobny ebxyt reaxcttiroanct)i.oMn)a. nMuaalniundale xiinndgehxiansgt hheaasd tvhaen taadgveaonfthaagvei nogf
haahviignhgd ae ghreigeho fdpergerceisei oonf inprtehceisdioensc riinp ttiohne odfersecsroiputricoens ,opfa rrteicsuoularrcleysi, npnaornti-ctuelxatrulyal rines onuornc-etsexstuucahl
raessiomuarcgeess sourcsho fatsw iamreagaepsp loirc astoioftnws.arHe oawpepvliecra,tiitoinssq. uHitoewceovsetlry, iatn ids iqnusitoem ceosctalsye sanladc kins csoonmseis tceansceys
liancdkes sccornipstiisotennscdyu ien tdoedscifrfieprteionnces sdiunec troit edriifafearmenocnesg iinn dcreixteerrisa. aTmheondga tianpdreoxverids.e Tdhien d[4a4ta] cparnovsiedrvede ains
[a4s4a] mcapnl es:er“v.e. .asY aa hsaomopulsee:s “2…00Yaemhopol ouyseees s2t0o0 ienmdepxlowyeeebs ptoa ginesdeinx awcecbo rpdaagnecse iwn iatchcoitrsd5a0n0c,e0 0w0i-tthe rimts
5ta0x0o,0n0o0m-tyer;mM EtaDxLoInNoEm(yt;h MenEaDtiLoInNalEm (tehdei cnaaltliiobnraarl ym)e[1d8i]caslp leinbdrasr$y2) [m18il]l isopnepnedrs y$e2a rmoinllitohne pinedr eyxeianrg oonf
tahreti cinledsewxiinthg tohfe aMrtiecSleHs wthietsha tuhreu sM.e.S.H” [t1h9e]s.aurus…” [19].
AAuuttoommaattiicc iinnddeexxiinngg,, iinn tthhee sseeccoonndd ccaassee,, uusseess aallggoorriitthhmmss tthhaatt ssttaattiissttiiccaallllyy aannaallyyzzee tthhee wwoorrddss iinn tthhee
ccoonntteennttss oorr mmeettaaddaattaa ooff tthhee rreessoouurrcceess [[4455]]. .MMeetataddaatata aarere aa seset toof fpproropperetriteise sanandd vavlauleuse sthtahta dtedsecsrcibrieb ae
raerseosuorucrec (eF(iFgiugruer 9e).9 I)n. Iinndinedxeinxgin bgyb ayuatoumtoamtiac teicxterxatcrtaioctni,o pna,tpteartntesr nofs wofowrdo brdehbaevhiaovr iaorrea irdeeindteifnietidfi oedn
tohne tbhaesibsa osifs soufchsu vcahrivaabrlieasb aless faresqfureeqnucye nocfy uosfe,u psela,cpelmaceenmt, eonrtd,eorr, daenrd, apnrdoxpimroixtiym. iItny .thIins twhaisy,w tahye,
wthoerwdso radnsda nredlarteiloantiso tnhsatth baetsbte rsetprerepsreenset nthteth ceocnotnentetns tosfo tfhteh ererseosouurcrece aarere idideennttiiffiieedd [[4466]].. IInn aauuttoommaattiicc
iinnddeexxiinngg bbyy aassssiiggnnmmeenntt,, tthhee wwoorrddsse exxtrtraacctetedda arerec ocmompparaerdedto toth tehete tremrmsos foaf cao cnotrnotlrloeldlevdo vcaobcuablaurlyartyo
tsoe lseecltetcht othseosteh athtaatr earme mosotssti msimilailraar sads edsecsrcirpitpotrosrso offt htheer eresosouurcrcee..T Thhee rreessuulltt aarree cclluusstteerrss ooff rreessoouurrcceess
tthhaatt sshhooww ssiimmiillaarr ccoonntteenntt ppaatttteerrnnss,, ttaaggggeedd bbyy mmeeaannss ooff tthhee sseeqquueennccee ooff tteerrmmss eexxttrraacctteedd ffrroomm tthhee
ccoonnttrroolllleedd vvooccaabbuullaarrieiesso orrw withitihninth tehree sroeusorcuersctehse tmhseemlvseeslv,ews h, icwhhbicehst breepstr erseepnrtetsheenirt ctohneitre nctosn[t8e,4n7ts].
A[8s,4a7]s. aAmsp al esaomfapuleto omf aatuictoimndaetixci ningdseyxsitnegm ssy(ssteeem[s4 8(s–e5e0 ][)48a–n5d0]A) manedri cAamneSroiccaient ySofocireItnyd feoxr iInngdleixstinogf
lsiosft twofa rseof[t5w1]a.reA u[5t1o]m. Aatuictoinmdaetxicin igndisexfainstge ri,sl efsasstceors, tlleys,sa ncdosmtlyo,r eancdon msisotreen tcothnasnistmenatn uthaalni nmdeaxniunagl,
ibnudtetxhiengle, vbeult othfea clecuveral coyf aocfcduersaccryi potfi odnesscirsiplotiwoners aisn ldowuseur aalnlyd ruesquuailrleys raeqcuerirteasin a dceegrtraeien odfehgureme aonf
hinuvmolavne minevnotlvtoemcoernrte ctot tchoerrreecstu tlhtseo rbetsauilntes do.btained.

Figure 9. Use of the UDC in the Dublin Core metadata. The subject attribute (DC.Subject) takes as its
Figure9.UseoftheUDCintheDublinCoremetadata.Thesubjectattribute(DC.Subject)takesasits
values a set of related vocabulary terms (hypernymy).
valuesasetofrelatedvocabularyterms(hypernymy).
In the third case, semiautomatic or hybrid indexing systems combine human involvement to
Inthethirdcase,semiautomaticorhybridindexingsystemscombinehumaninvolvementtoidentify
identify the potential meanings of the resources and the efficiency of automatic indexing [47]. They
thepotentialmeaningsoftheresourcesandtheefficiencyofautomaticindexing[47]. Theyareableto
are able to learn with experience, which makes them increasingly efficient. One example is the Verity
documentary indexing systems used by Oracle [52].
Educ.Sci.2017,7,33 10of38
learnwithexperience,whichmakesthemincreasinglyefficient.OneexampleistheVeritydocumentary
indexingsystemsusedbyOracle[52].
Tocreateindexingvocabularies,threepointsshouldbetakenintoaccount:firstly,inthedesignstage,
it should be verified whether there are standard reference vocabularies for the domain of knowledge
ofthecollectionofresourcesthatcanbeusedtotallyorpartiallybeforecreatinganewoneadhoc.
Thereasonforthisistwofold:notonlydoesitreducecosts,butalsofacilitatesinteroperabilitybetween
repositoriesandIRsystems,forexample,totransferthevocabularytopotentialnewversionsofthe
repositoryortootherinformationsystems. Iftherearenosuchvocabulariesandonemustbecreated
fromscratch,thestandardguidelinesforthecreationofvocabulariesshouldbefollowed,toguarantee
theinteroperabilityofthevocabularyineverycase[9,10,53–56].
Secondly,itshouldbetakenintoaccountwhetherthevocabularywillbeusedincombinationwith
metadatatodescribetheresources. Thisisafrequentoption,whichisdescribedinSection5. Basically,
itconsistsinusingthetermsofoneorseveralvocabulariestoassignvaluestothepropertiesofthe
resource metadata. Figure 9 shows use of the Universal Decimal Classification (UDC) to describe
aresourceinhtmlformat. ThemetadatamodelisDublinCore[57],whichisprobablytheonemost
frequentlyusedontheInternet.
Thirdlyandfinally,whencreatingnewvocabularies,itshouldbeborneinmindwhetherthey
will be also used in the IR system search, navigation, and personalization systems. This option has
the advantages that not only are the costs of creation capitalized, but also the maintenance of the
conceptualanddesignatoryconsistencyofthecollectionresourcesisfacilitated,whichhelpsusers
to have a mental image of what the collection of resources is like, and thus locate more easily the
resourcessought.
4.2. SearchandNavigationVocabulary
Tounderstandtheroleofvocabulariesinsearchandnavigation,thefollowingtypesofIRandonline
resourceretrievalsystemsshouldbedistinguished: browsing,searching,andfilteringsystems[47].
1. Browsingsystemsofferusersanorganizedtermstructure,whichisthevocabulary,whichincludes
the information resources and a mechanism that allows users to browse the vocabulary to
locatetheresourcessought. Thewayinwhichthevocabularyispresentedrangesfromsimple
navigationinanalphabeticallistrestrictedtothevocabularyterms(Figure10)tohybridsystems
thatmakeitpossibletoselecttermswhilebrowsingthroughthevocabularytocombinethemin
anexpressionthatdescribeswhatisbeingsought[58].
2. Searchsystemsofferusersthepossibilityofdefiningtheresource(s)soughtbyenteringtheterms
thatdescribesaidresourceinatextbox(Figure11). Thesesystemsaresuitableifusersareable
toexpressinsufficientdetailwhattheyarelookingfor, thatis, theyknowbeforehandwhich
informationorresourcestheyseek(andconsequentlydonotneedto“browse”asintheprevious
case). Thevocabularyinthiskindofsystembasicallyservesasaterminologicalreferencesystem
foruserstousethesametermsemployedbytheIRsystemtoindextheinformationorresources.
Inthisway,bettersearchresultsareguaranteed(recallandaccuracy). Inbrowsingandretrieval
systems,usersinteractinrealtimewiththeIRsearchmodule.
3. Filteringsystemsallowuserstodefinetheircontentpreferencesintheirprofile. Thesepreferences
(e.g.,SpanishLiterature)areusedbytheIRsystemtofiltertheresourcesandofferusersonly
thoseresourcesinwhichtheyareinterested. Inthiskindofsystem,thevocabularyallowsusers
toselectthetermsthatdefinetheirpreferences,whicharethesametermsusedbytheIRsystem
toindextheresources. Oneexampleofuseofthissystemisthe“MyMERLOT”optioninthe
MERLOTeducationalrepository(Figure12).