1. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
Web semantic
Dr. SabinCorneliu Buraga
Facultatea de Informatica
Universitatea “A.I.Cuza” – Iasi, Romania
http://www.infoiasi.ro/~busaco/
Dr. Sabin Buraga http://www.purl.org/net/busaco
3. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
“Toate erau laolalta – dupa aceea a venit mintea
si le‐a pus in ordine.”
Anaxagoras
Dr. Sabin Buraga http://www.purl.org/net/busaco
4. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
constatare
Declaratiile RDF se situeaza la nivel de
instante (indivizi)
Dr. Sabin Buraga http://www.purl.org/net/busaco
5. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
constatare
Lipseste un mecanism de declarare
a unui vocabular
Dr. Sabin Buraga http://www.purl.org/net/busaco
6. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
constatare
<rdf:Description rdf:about=http://www.apple.com/macbook>
<s:Produs>MacBook</s:Produs>
</rdf:Description>
In loc de produs putem folosi laptop ori marfa?
Conceptul produs este definit in relatie cu altele?
Resursa descrisa poate fi modelata diferit?
Ce proprietati sunt asociate unui produs?
Dr. Sabin Buraga http://www.purl.org/net/busaco
7. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
necesitati
Un mecanism de specificare
a unui model de cunostinte privitor la un web
specificarea unei taxonomii a resurselor
Dr. Sabin Buraga http://www.purl.org/net/busaco
8. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
necesitati
O modalitate de a specifica
relatiile dintre (clase de) resurse
RDF este un model care permite specificarea de relatii
intre doua obiecte
Dr. Sabin Buraga http://www.purl.org/net/busaco
9. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
necesitati
Ne‐ar fi util un model ce permite definirea
unei taxonomii, in termeni de clase, superclase
si subclase de resurse
Dr. Sabin Buraga http://www.purl.org/net/busaco
10. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii
Taxonomia reprezintă studiul principiilor
generale de clasificare ştiințifică,
i.e. clasificarea sistematică
detalii in (Daum et al., 2003)
Dr. Sabin Buraga http://www.purl.org/net/busaco
11. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii
Resursele pot fi clasificate sub forma unei ierarhii,
conform unor relații în prealabil fixate stabilite
între entitățile pe care le reprezintă în lumea reală
Dr. Sabin Buraga http://www.purl.org/net/busaco
12. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii
Taxonomie ≡ arbore:
noduri – concepte (clase)
relații dintre noduri – relații de sub‐/supra‐clasificare
(generalizare/specializare)
Dr. Sabin Buraga http://www.purl.org/net/busaco
13. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii
Fiecare nod (entitate) poseda
o proprietate specifica, proprietate caracteristica
sub‐clasei din care face parte
Dr. Sabin Buraga http://www.purl.org/net/busaco
14. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
Conform (Alan Rector et al., 2004)
taxonomii: exemplu
Dr. Sabin Buraga http://www.purl.org/net/busaco
15. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii: exemplu
Conform (Christian Ricci, 2004)
Dr. Sabin Buraga http://www.purl.org/net/busaco
17. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii: utilizari
Clasificarea resurselor
model simplu de clasificare
taxonomie = ontologie simpla
Dr. Sabin Buraga http://www.purl.org/net/busaco
18. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii: utilizari
exemplu mentionat de (Bouquet, Serafini & Zanobini, 2005)
Dr. Sabin Buraga http://www.purl.org/net/busaco
19. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii: utilizari
Structuri de directoare de fisiere
Categorii de situri Web – cataloage, directories
Open Directory: dmoz.org
Comert electronic
Universal Standard Products and Services Classification:
www.eccma.org
Dr. Sabin Buraga http://www.purl.org/net/busaco
20. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii: utilizari
Clasificarea serviciilor Web
se realizeaza via tModel,
folosindu‐se North American Industry Classification System
Dr. Sabin Buraga http://www.purl.org/net/busaco
21. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
taxonomii: model
Modelarea poate fi realizata via scheme RDF
Dr. Sabin Buraga http://www.purl.org/net/busaco
22. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Permite definirea de taxonomii
în termeni de clase, super‐clase şi sub‐clase de resurse
(Brickley & Guha, 2004)
Dr. Sabin Buraga http://www.purl.org/net/busaco
23. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Recomandare a Consortiului Web
www.w3.org/TR/rdfschema/
Dr. Sabin Buraga http://www.purl.org/net/busaco
24. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Ofera o modalitate de specificare
a unui vocabular de termeni si
de relatii intre acesti termeni
precizeaza contructiile – conceptele – ce pot fi utilizate
intr‐un domeniu dat
poate descrie relatiile dintre elementele de vocabular
apartinind unor vocabulare diferite
Dr. Sabin Buraga http://www.purl.org/net/busaco
25. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Adauga semantica predicatelor si resurselor RDF
poate defini maniera in care un termen trebuie interpretat,
specificindu‐i proprietatile sale si stabilind ce tipuri
de “lucruri” pot fi valorile acestor proprietati
Dr. Sabin Buraga http://www.purl.org/net/busaco
26. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Contine definitii si restrictii de utilizare
a proprietatilor
Fiecare predicat e identificat printr‐o schema unica
Pune la dispozitie maniere de specificare
a claselor si proprietatilor obiectelor
in contextul utilizarii unui vocabular
Dr. Sabin Buraga http://www.purl.org/net/busaco
27. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: terminologie
Clasa (Class) & proprietatea (Property)
Persoana, type, Class
areIdentitate, type, Property
Aplicatie, type, Class
ruleazaPe, type, Property
Dr. Sabin Buraga http://www.purl.org/net/busaco
29. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: terminologie
O schema RDF fiind exprimata prin triple RDF,
pot fi efectuate interogari SPARQL:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?clasa
WHERE {
?clasa rdf:type rdfs:Class
}
ORDER BY ?clasa
Dr. Sabin Buraga http://www.purl.org/net/busaco
30. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: model
Clase fundamentale:
rdfs:Resource – clasa resurselor
rdf:Property – clasa proprietatilor resurselor
rdfs:Class – corespunde conceptului de tip sau categorie
rdfs:Container – clasa generica privind
containerele de date RDF
rdfs:Datatypes – clasa tipurilor de date
Dr. Sabin Buraga http://www.purl.org/net/busaco
31. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: model
Clasele specifica resurse Web (identificate de URI):
pagini
tipuri de documente
baze de date
persoane
…
Dr. Sabin Buraga http://www.purl.org/net/busaco
32. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: model
Resursele apartinind unei clase = instante
clase specificate via RDF Schema
instantele sunt exprimate prin RDF
Dr. Sabin Buraga http://www.purl.org/net/busaco
33. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: model
Proprietati fundamentale:
rdf:type – indica faptul ca o resursa
este membra a unei clase
rdfs:subClassOf – relatia de mostenire
a claselor (tranzitiva)
rdfs:subPropertyOf – relatia de mostenire a proprietatilor
Dr. Sabin Buraga http://www.purl.org/net/busaco
34. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Clasa Multimedia include subclasele Audio si Video
<rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns#
xmlns:rdfs=http://www.w3.org/2000/01/rdf-schema#>
<rdf:Description rdf:ID=Multimedia>
<rdf:type rdf:resource=
http://www.w3.org/2000/01/rdf-schema#Class />
</rdf:Description>
<rdf:Description rdf:ID=Video>
<rdf:type rdf:resource=
http://www.w3.org/2000/01/rdf-schema#Class />
<rdfs:subClassOf rdf:resource=#Multimedia />
</rdf:Description>
Dr. Sabin Buraga http://www.purl.org/net/busaco
35. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Clasa Multimedia include subclasele Audio si Video
(continuare)
<rdf:Description rdf:ID=Audio>
<rdf:type rdf:resource=
http://www.w3.org/2000/01/rdf-schema#Class />
<rdfs:subClassOf rdf:resource=#Multimedia />
</rdf:Description>
</rdf:RDF>
Dr. Sabin Buraga http://www.purl.org/net/busaco
36. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: model
Restrictii:
impuse asupra claselor si/sau proprietatilor
rdfs:range – restrictioneaza valorile unei proprietati
rdfs:domain – specifica o clasa care poate fi asignata
ca valoare a unei proprietati
Dr. Sabin Buraga http://www.purl.org/net/busaco
37. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Clasei Multimedia ii asociem proprietatea duration
cu valori din multimea numerelor intregi
<rdfs:Property rdf:ID=duration>
<rdfs:domain rdf:resource=#Multimedia />
<rdfs:range rdf:resource=#Integer />
</rdf:Description>
Dr. Sabin Buraga http://www.purl.org/net/busaco
39. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: model
Remarca:
nu e obligatoriu sa definim conceptul Integer
ipoteza lumilor deschise
contrast cu modelul bazelor de date clasice
Dr. Sabin Buraga http://www.purl.org/net/busaco
41. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu (Ide, 2003)
Parte de vorbire
subClassOf of
sub-class of sub-class
subClassOf
Substantiv Verb
SubiectAl subClassOf
domain
domain
sub-class of sub-class of
range
Subst. comun Verb reflexiv
Nivelul ontologic
Nivelul datelor
type type
SubiectAl
Crocodilii se joaca
Dr. Sabin Buraga http://www.purl.org/net/busaco
42. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Definirea claselor:
<rdfs:Class rdf:about=
http://www.linguistics.org/schema.rdf#PartOfSpeech>
<rdfs:label>POS</rdfs:label>
<rdfs:comment xml:lang=ro>Clasa desemnind categoria generala
“parte de vorbire”</rdfs:comment>
</rdfs:Class>
<rdfs:Class rdf:about=http://www.linguistics.org/schema.rdf#Noun>
<rdfs:label>Noun</rdfs:label>
<rdfs:comment xml:lang=ro>Clasa substantivelor</rdfs:comment>
<rdfs:subClassOf rdfs:resource=
http://www.linguistics.org/schema.rdf#PartOfSpeech/>
</rdfs:Class>
Dr. Sabin Buraga http://www.purl.org/net/busaco
43. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Definirea proprietatilor:
<rdfs:Property rdf:about=
http://www.linguistics.org/schema.rdf#number>
<rdfs:domain rdf:resource=
http://www.linguistics.org/schema.rdf#PartOfSpeech />
<rdfs:range rdf:resource=
http://www.w3.org/2000/01/rdf-schema#Literal />
</rdfs:Property>
Dr. Sabin Buraga http://www.purl.org/net/busaco
44. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Folosirea – la nivel de instante – a schemei RDF specificate:
<rdf:RDF
xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns#
xmlns:pos=http://www.linguistics.org/schema.rdf#>
<s:Stiri xmlns:s=http://www.stiri.ro/crocodili>
<pos:Noun rdf:ID=crocodilii>
<pos:number rdf:value=Plural />
</pos:Noun>
<pos:Verb rdf:ID=se_joaca>
<pos:number rdf:value=Plural />
</pos:Verb>
</s:Stiri>
</rdf:RDF>
Dr. Sabin Buraga http://www.purl.org/net/busaco
46. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Modelarea calendarelor de evenimente
inspirat de (Manjunath et al., 2008):
cal:Vevent a rdfs:Class .
cal:attendee a rdf:Property ;
:RoCHI08 rdf:type cal:Vevent ;
rdfs:domain cal:Vevent ;
cal:location [ :city Iasi ] ;
rdfs:range foaf:Person .
cal:dtstart 2008-09-18T09:00:00 ;
cal:location a rdf:Property .
cal:dtend 2008-09-19T18:00:00 ;
cal:dtstart a rdf:Property .
cal:relatedTo :RoCHI07 .
cal:dtend a rdf:Property .
cal:relatedTo a rdf:Property ;
o posibila instanta
rdfs:domain cal:Vevent ;
de eveniment
rdfs:range cal:Vevent .
Dr. Sabin Buraga http://www.purl.org/net/busaco
47. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Clasele si proprietatile sunt modelate separat
Spre deosebire de paradigma orientata‐obiect,
proprietatile (atributele) nu fac parte din clasa
Nu se pot exprima relatii complexe intre clase
(reuniune, disjunctie,...),
nici cardinalitatea – e.g., “cel putin una”
Dr. Sabin Buraga http://www.purl.org/net/busaco
48. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Se ofera suport pentru modelarea
clasificarilor de resurse
Dr. Sabin Buraga http://www.purl.org/net/busaco
49. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Strategii privind organizarea continutului (Ricci, 2004):
ierarhie unica – strategia de navigare intre concepte
reprezinta insasi taxonomia adoptata
Dr. Sabin Buraga http://www.purl.org/net/busaco
50. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Strategii privind organizarea continutului (Ricci, 2004):
asocieri de continut (content mapping) – managementul
continutului e independent de modul de navigare;
pot fi folosite mai multe criterii de clasificare,
eventual pe baza meta‐datelor aferente
identificarea relatiilor de baza: sub/supra‐clase, elemente
aflate pe acelasi nivel al arborelui taxonomic (peers)
Dr. Sabin Buraga http://www.purl.org/net/busaco
51. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Strategii privind organizarea continutului (Ricci, 2004):
Dr. Sabin Buraga http://www.purl.org/net/busaco
52. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Modelarea datelor pentru o aplicatie de ascultat
CD‐uri: cdream (Victor Grigoriu, 2003)
Clase:
CD – http://cdream.ro/CD
Piesa – http://cdream.ro/Piesa
Dr. Sabin Buraga http://www.purl.org/net/busaco
53. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Aplicatia cdream (Victor Grigoriu, 2003)
Proprietati:
Durata piesei (min:sec) – http://cdream.ro/Lung
Interpret/compozitor – http://cdream.ro/Artist
Titlul (piesei/albumului) – http://cdream.ro/Titlu
Lista pieselor de pe album – http://cdream.ro/Contine
(are ca obiect un rdf:Seq)
Genul muzical – http://cdream.ro/GenMuzical
Numele artistului – http://cdream.ro/Nume
Dr. Sabin Buraga http://www.purl.org/net/busaco
54. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Aplicatia cdream (Victor Grigoriu, 2003)
Restrictii:
Proprietatea Contine se aplica numai clasei CD
Proprietatea Lung este specifica doar clasei Piesa
Proprietatea Nume se asociaza autorilor,
reprezentati ca resurse (noduri blanc)
Dr. Sabin Buraga http://www.purl.org/net/busaco
57. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Aplicatia cdream (Victor Grigoriu, 2003)
implementare in limbajul C++,
folosind biblioteca Redland – sub Linux
procesarea datelor RDF a recurs la analizorul Raptor
interfata cu utilizatorul bazata pe Qt
Dr. Sabin Buraga http://www.purl.org/net/busaco
58. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Reprezinta un model de specificare explicita
a relatiilor dintre clase de “lucruri” de interes
Dr. Sabin Buraga http://www.purl.org/net/busaco
59. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Pune bazele efectuarii automate de inferente
e.g., “descoperirea” relatiilor intre resurse – contrast cu
OOP unde relatiile de dependenta sunt specificate apriori
Dr. Sabin Buraga http://www.purl.org/net/busaco
60. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Pune bazele efectuarii automate de inferente
Pentru subclase, avind triple de forma:
A rdfs:subclassOf B .
r rdf:type A .
putem deduce:
r rdf:type B .
triplu dedus
(inferred triple)
Dr. Sabin Buraga http://www.purl.org/net/busaco
61. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Pune bazele efectuarii automate de inferente
Pentru subproprietati, avind triple de forma:
P rdfs:subPropertyOf R .
APB.
putem deduce:
ARB.
triplu dedus
(inferred triple)
Dr. Sabin Buraga http://www.purl.org/net/busaco
62. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Pune bazele efectuarii automate de inferente
In cazul specificarii domeniului, avind triple de forma:
P rdfs:domain D .
xPy.
putem deduce:
x rdf:type D .
triplu dedus
(inferred triple)
Dr. Sabin Buraga http://www.purl.org/net/busaco
63. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Pune bazele efectuarii automate de inferente
In cazul specificarii intervalului, avind triple de forma:
P rdfs:range R .
xPy.
putem deduce:
y rdf:type R .
triplu dedus
(inferred triple)
Dr. Sabin Buraga http://www.purl.org/net/busaco
64. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Modelarea unui web privitor la familii de persoane:
:FemeieMaritata rdfs:subClassOf :Femeie .
:numeDeFata rdfs:domain :FemeieMaritata .
La nivel de instante, avem specificat:
:Raluca :numeDeFata Morosan .
Putem deduce automat ca
:Raluca rdf:type :Femeie .
Dr. Sabin Buraga http://www.purl.org/net/busaco
65. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: exemplu
Modelarea unui web privitor la familii de persoane:
Dr. Sabin Buraga http://www.purl.org/net/busaco
66. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema
Generalizind, avind disponibile triplele:
P rdfs:domain D .
D rdfs:subClassOf C .
putem deduce:
P rdfs:domain C .
in RDF Schema, mostenirea inseamna de fapt inferenta
Dr. Sabin Buraga http://www.purl.org/net/busaco
67. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: sabloane
Desi sintactic nu exista suport pentru specificarea
operatiilor cu clase (intersectie, reuniune),
le putem exprima folosind regulile de inferenta
(Allemang & Hendler, 2008)
modelling patterns
Dr. Sabin Buraga http://www.purl.org/net/busaco
68. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: sabloane
Intersectia de multimi (clase):
C rdfs:subClassOf A .
C rdfs:subClassOf B .
avind dat triplul
r rdf:type C .
am realizat
se poate deduce:
inferenta intr‐o
r rdf:type A . singura directie
r rdf:type B .
Dr. Sabin Buraga http://www.purl.org/net/busaco
69. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: sabloane
Intersectia de multimi (clase) – exemplu:
:Masterand rdfs:subClassOf :Student .
:Masterand rdfs:subClassOf :DezvoltatorWeb .
:Ciprian rdf:type :Masterand .
se poate deduce:
:Ciprian rdf:type :Student .
:Ciprian rdf:type :DezvoltatorWeb .
un individ apartinind claselor Student si DezvoltatorWeb
nu e obligatoriu sa fie membru si al clasei Masterand
Dr. Sabin Buraga http://www.purl.org/net/busaco
70. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: sabloane
Similar, se poate modela intersectia de proprietati
Dr. Sabin Buraga http://www.purl.org/net/busaco
71. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: sabloane
Reuniunea de multimi:
A rdfs:subClassOf C .
B rdfs:subClassOf C .
avind r rdf:type A . sau r rdf:type B .
se poate deduce:
r rdf:type C .
Dr. Sabin Buraga http://www.purl.org/net/busaco
72. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: sabloane
Reuniunea de multimi – exemplu:
:Sit rdfs:subClassOf :Produs .
:ServiciuWeb rdfs:subClassOf :Produs .
:SolutieEBanking rdf:type :ServiciuWeb .
(sau :SolutieEBanking rdf:type :Sit .)
se poate deduce:
:SolutieEBanking rdf:type :Produs .
Dr. Sabin Buraga http://www.purl.org/net/busaco
73. <?xml version=“1.0” ?>
Semantic Web <curs desc=“…” />
rdf schema: sabloane
“Transferul” de proprietati:
P rdfs:subPropertyOf Q .
avind triplul
XPY.
se poate deduce:
XQY.
Dr. Sabin Buraga http://www.purl.org/net/busaco
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rdf schema: sabloane
“Transferul” de proprietati:
are utilizari in reconcilierea terminologiilor
:autor rdfs:subPropertyOf dc:creator .
bib:imprumutaCarte rdfs:subPropertyOf :posedaVolum .
lib:borrows rdfs:subPropertyOf :posedaVolum .
Dr. Sabin Buraga http://www.purl.org/net/busaco
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rdf schema: alte constructii
Referinte la alte resurse:
rdfs:seeAlso – proprietate care indica o resursa continind
informatii suplimentare privitoare la resursa asociata
Dr. Sabin Buraga http://www.purl.org/net/busaco
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rdf schema: alte constructii
Referinte la alte resurse:
<rdf:Description rdf:ID=MSD>
<s:nume xml:lang=ro>
Master de Sisteme Distribuite
</s:nume>
<rdfs:seeAlso rdf:resource=http://www.infoiasi.ro/msd />
<!-- informatii suplimentare -->
</rdf:Description>
Dr. Sabin Buraga http://www.purl.org/net/busaco
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rdf schema: alte constructii
Organizarea vocabularelor:
rdfs:isDefinedBy – subproprietate a rdfs:seeAlso
ce desemneaza o legatura spre sursa primara de informatii
despre o resursa data
Dr. Sabin Buraga http://www.purl.org/net/busaco
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rdf schema: alte constructii
Modelul RDF Schema specificat in RDF Schema – fragment:
<rdf:Property
rdf:about=http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<rdfs:isDefinedBy
rdf:resource=http://www.w3.org/1999/02/22-rdf-syntax-ns#/>
<rdfs:label>type</rdfs:label>
<rdfs:comment>The subject is an instance of a class.</rdfs:comment>
<rdfs:range
rdf:resource=http://www.w3.org/2000/01/rdf-schema#Class/>
<rdfs:domain
rdf:resource=http://www.w3.org/2000/01/rdf-schema#Resource/>
</rdf:Property>
Dr. Sabin Buraga http://www.purl.org/net/busaco
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class name comment
rdfs:Resource The class resource, everything.
rdfs:Literal The class of literal values, e.g. textual strings and integers.
rdf:XMLLiteral The class of XML literals values.
rdfs:Class The class of classes.
rdf:Property The class of RDF properties.
rdfs:Datatype The class of RDF datatypes.
rdf:Statement The class of RDF statements.
rdf:Bag The class of unordered containers.
rdf:Seq The class of ordered containers.
rdf:Alt The class of containers of alternatives.
rdfs:Container The class of RDF containers.
rdfs:Container The class of container membership properties,
rdf:_1, rdf:_2, ..., all of which are subproperties of 'member'.
MembershipProperty
rdf:List The class of RDF Lists.
Dr. Sabin Buraga http://www.purl.org/net/busaco
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rdf schema: privire de ansamblu
property name comment domain range
The subject is an instance
rdf:type rdfs:Resource rdfs:Class
of a class.
rdfs:subClassOf The subject is a subclass of a class. rdfs:Class rdfs:Class
rdfs: The subject is a subproperty
rdf:Property rdf:Property
of a property.
subPropertyOf
rdfs:domain A domain of the subject property. rdf:Property rdfs:Class
rdfs:range A range of the subject property. rdf:Property rdfs:Class
A humanreadable name
rdfs:label rdfs:Resource rdfs:Literal
for the subject.
A description of the subject
rdfs:comment rdfs:Resource rdfs:Literal
resource.
rdfs:member A member of the subject resource. rdfs:Resource rdfs:Resource
Dr. Sabin Buraga http://www.purl.org/net/busaco
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property name comment domain range
rdf:first First item in the subject RDF list. rdf:List rdfs:Resource
Rest of the subject RDF list
rdf:rest rdf:List rdf:List
after the first item.
Further information about
rdfs:seeAlso rdfs:Resource rdfs:Resource
the subject resource.
The definition of the subject
rdfs:isDefinedBy resource. rdfs:Resource rdfs:Resource
Idiomatic property used
rdf:value rdfs:Resource rdfs:Resource
for structured values.
The subject of the subject
rdf:subject rdf:Statement rdfs:Resource
RDF statement.
The predicate of the subject
rdf:predicate rdf:Statement rdfs:Resource
RDF statement.
The object of the subject
rdf:object rdf:Statement rdfs:Resource
RDF statement.
Dr. Sabin Buraga http://www.purl.org/net/busaco
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intrebare
Exista posibilitatea folosirii unui model conceptual
mai expresiv?
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure
Thesaurus: a controlled vocabulary arranged
in a known order and structured so that
equivalence, homographic, hierarchical,
and associative relationships among terms
are displayed clearly and identified by standardized
relationship indicators
Conform ANSI/NISO Monolingual Thesaurus Standard
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure
Relatii
Echivalenta
termenul X are (aproape) acelasi inteles cu termenul Y
“Pagina Web” sinonim cu “document Web”
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure
Relatii
Omonimia (omografia)
termenul X se pronunta/scrie la fel ca si Y,
dar are alt inteles
“toc” versus “toc” versus “toc”
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure
Relatii
Ierarhie
termenul X are un inteles mai larg/restrins
decit termenul Y
“patrulater” versus “dreptunghi”
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure
Relatii
Asociere
termenul X este asociat termenului Y
(e.g., exista o relatie nespecificata intre ei)
“cui”/“Pink Floyd” asociat lui “ciocan”
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure
Un tezaur asigura urmatoarele:
conceptele se descriu intr‐un mod consistent
utilizatorii experimentati pot sa‐si rafineze cautarile
pentru localizarea informatiilor dorite din tezaur
utilizatorii nu trebuie sa fie familiarizati
cu terminologia tehnica (particulara) folosita
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: exemple
Center for Army Lessons Learned (CALL) Thesaurus
National Cancer Institute (NCI) Thesaurus
AGROVOC – indexarea multilingva a resurselor privitoare
la agricultura realizata la nivelul Natiunilor Unite
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: exemple
Roget’s Thesaurus – parte din proiectul Gutenberg
www.cix.co.uk/~andie/cogito/roget.shtml
WordNet
www.cogsci.princeton.edu/~wn/
schema RDF disponibila la http://xmlns.com/2001/08/wordnet/
SWAD (Semantic Web Advanced Development) Thesaurus
www.w3c.rl.ac.uk/SWAD/thesaurus.html
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: exemple
(Daconta, Obrst & Smith, 2003)
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Simple Knowledge Organizational System
exprimă cunoştințele în cadrul sistemelor organizaționale,
în general, şi a tezaurelor, în special (Mikhalenko, 2005)
propus de Consortiul Web
model bazat pe RDF şi scheme RDF
http://www.w3.org/TR/skos-primer
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Niveluri de specificare:
SKOS Core – modeleaza in special tezaure
utilizeaza spatiul de nume
http://www.w3.org/2004/02/skos/core
SKOS Mapping – extensie ce permite asocierea
de concepte din tezaure diferite
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Exemplu: definirea conceptului de instrument
<skos:Concept rdf:about=#instrument>
<skos:definition>Obiect utilizat într-un anumit scop</skos:definition>
<!-- specializare a unui alt concept -->
<skos:narrower rdf:resource=#obiect/>
<!-- concepte înrudite -->
<skos:related rdf:resource=#unealta/>
<skos:related rdf:resource=#dispozitiv/>
<skos:related rdf:resource=#mecanism/>
<skos:scopeNote>...</skos:scopeNote>
</skos:Concept>
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Specificarea tezaurului arhivelor nationale britanice
UK Archival Thesaurus (Allemang & Hendler, 2008)
UKAT:EconomicCooperation a skos:Concept ;
skos:altLabel Economic co-operation ;
skos:broader UKAT:EconomicPolicy;
skos:narrower UKAT:IndustrialCooperation,
UKAT:EconomicIntegration ; relatii dintre
concepte:
skos:prefLabel Economic cooperation ; broader, narrower
skos:related UKAT:Interdependence ; si related
skos:scopeNote ... .
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Pot fi specificate si colectii de concepte via skos:Collection
agro:LapteDupaTipulDeAnimal rdf:type skos:Collection ;
skos:member agro:LapteDeVaca ;
skos:member agro:LapteDeCapra ;
skos:member agro:LapteDeOaie .
agro:LapteDeVaca rdf:type skos:Concept ;
skos:prefLabel Lapte de vaca .
agro:Lapte skos:narrower agro:LapteDupaTipulDeAnimal .
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Coordonarea conceptelor (pre‐ si post‐coordonare)
– suport pentru indexarea perechilor de concepte
s:floare skos:prefLabel Floare@ro .
Cum specificam
s:soare skos:prefLabel Soare@ro . “floarea soarelui”?
extindem SKOS cu proprietatea s:coordinationOf astfel:
s:coordinationOf a rdf:Property ;
rdfs:domain skos:Concept ;
rdfs:range rdf:List .
Dr. Sabin Buraga http://www.purl.org/net/busaco
99. <?xml version=“1.0” ?>
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tezaure: skos
Coordonarea conceptelor (pre‐ si post‐coordonare)
s:floareaSoarelui a skos:Concept ;
s:coordinationOf (s:floare s:soare) ;
skos:prefLabel Floarea-soarelui@ro .
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Specificarea de relatii tranzitive intre concepte via
skos:broaderTransitive si skos:narrowerTransitive
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tezaure: skos
Specificarea de relatii tranzitive intre concepte via
skos:broaderTransitive si skos:narrowerTransitive
detalii in Isaac & Summers, SKOS Primer, W3C, 2008
Dr. Sabin Buraga http://www.purl.org/net/busaco
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tema
Specificati in RDF(S) clasele, proprietatile si relatiile
privitoare la tipurile de angajati si artefactele asociate:
(Daconta et al., 2003)
Dr. Sabin Buraga http://www.purl.org/net/busaco
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Rezumat
Modelarea taxonomiilor si tezaurelor prin
RDF Schema si realizarea inferentelor simple
Dr. Sabin Buraga http://www.purl.org/net/busaco