Web07 Semantic Web: Ontologii -- Logicile Descrierii
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Transcript of Web07 Semantic Web: Ontologii -- Logicile Descrierii
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
Web semantic
Dr. Sabin-Corneliu BuragaFacultatea de InformaticaUniversitatea “A.I.Cuza” – Iasi, Romaniahttp://www.infoiasi.ro/~busaco/
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
Ontologii
formalizare: logicile descrierii
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
“O harta nu inseamna teritoriul.”Alfred Korzybski
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
realitati
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
realitati
Ontologiile au drept scopmodelarea unei (parti a unei) lumitermenii limbajului de modelare folositcorespund entitatilor din cadrul lumii
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
realitati
Tipic, ontologiile prezinta 2 componente distincte:nume privind conceptele importanteElefant este clasa ai carei membri sunt animaleIerbivor este conceptul desemnind animalele ce consuma doarplante ori parti dintr-o plantacunostinte anterioare/constringeri ale lumii modelateelefantii sunt africani sau indieniun individ nu poate fi simultan ierbivor si carnivoro persoana e adulta, atunci cind are virsta de minim 18 ani
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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intrebare
In ce maniera exprimam – formal – intelesul(meaning) constructiilor modelate?
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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raspuns
Intelesul (meaning) e dat de asocierea unui formalisme.g., logica de ordin I (FOL – First Order Logic)
un model teoretic ofera un mecanism de asocierede relatii intre sintaxa si interpretari
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logici
Pentru o constructie sintactica, pot exista mai multe sensuri (interpretari, modele)termenul “toc” ≠ termenul “toc”Modelele se presupune ca sunt analoageunei (parti a unei) lumielementele modelului corespund obiectelor lumii
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logiciTrebuie data o relatie formalaintre sintaxa si modelestructura modelelor reflecta relatiile specificatein cadrul sintaxeiutilizarea unei/unor logici
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logici
Logicilimbaje formalizate menite a reprezenta informatiicu scopul de a putea fi deduse concluziisintaxa defineste propozitiile (sentences)in cadrul limbajului folositsemantica defineste intelesul (formal) al propozitiilor– i.e., specifica adevarul (truth) unei propozitieiin cadrul lumii modelate
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logiciExemplu: limbajul aritmeticx + 33 > y este o propozitie; x33 + y > nu e propozitie
x + 33 > y este adevarata (true) iffnumarul x + 33 nu e mai mic decat numarul y
x + 33 > y este true intr-o lume in care x = 1 si y = 7x + 33 > y este false intr-o lume in care x = 1 si y = 69
x + 33 > x este true in orice lume (tautologie)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logiciLogicile sunt caracterizate de ceea ce exprima (commit)ca “primitive”declaratii ontologice – exprima ce anume exista:fapte (facts), lucruri (things), timp (time), credinte (beliefs)declaratii epistemologice – exprima care este stareacunoasterii acumulate
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logici
Limbaj (logic) Declaratii ontologice(Ce anume exista) Declaratii epistemologice (Ce cunoaste o entitate/agent)Logica prop. fapte (facts) true/false/unknownLogica de ordin I (FOL) fapte, obiecte, relatii true/false/unknownLogica temporala fapte, obiecte, relatii, timp true/false/unknownTeoria probab. fapte grade de cunoastere (belief) 0..1Logica fuzzy grade de adevar grade de cunoastere (belief) 0..1conform (Enrico Franconi, 2003)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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necesitatea folosirii unei/unor logici
Modelelumi avand o anumita structurain care adevarul poate fi evaluat (dedus)m este model pentru o propozitie pdaca p este true in cadrul modelului m
M (p) reprezinta multimea tuturor modelelor lui p
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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necesitatea folosirii unei/unor logici
Baza de cunostinte (KB – knowledge base)multime de propozitii descrise intr-un limbaj formalizat= teorie logicacontine cunostintele privitoare la lumea modelatacare pot fi manipulate via algoritmi deductivi(inclusi intr-un motor de inferenta – inference engine)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logici
Baza de cunostinte KB determina, implica, satisface(entails) propozitia p – adica KB ² p – daca si numai dacap este true in toate lumile in care KB este truedat fiind modelul M (p), KB ² p daca si numai daca M (KB) ⊆M (p)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
necesitatea folosirii unei/unor logici
Baza de cunostinte KB deduce, infera (infer)propozitia p folosind procedura i – adica KB `i p –daca si numai daca p poate fi dedusa (derivata) din KBde catre procedura (algoritmul) iSoundness: i este sound daca avand KB `i patunci e adevarat ca KB ² pCompleteness: i este complete daca KB ² pimplica faptul ca KB `i p
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
formalizareDomeniul modelat – partea lumii modelate de ontologie – este interpretat ca o multime (set) Δ
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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formalizareObiectele (entitatile, things) lumii sunt interpretateca elemente ale lui Δ:clasele/conceptele (predicate unare)sunt submultimi ale lui Δproprietatile/rolurile (predicate binare)sunt submultimi ale lui Δ × Δ = Δ2predicatele ternare sunt submultimi ale lui Δ3s.a.m.d.
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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formalizare
De exemplu, relatia subClassOf dintre clasepoate fi interpretata ca o incluziune de multimi
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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Lumea Interpretarea
Tux isA PinguinPinguin kindOf AnimalCaty isA PersoanaPersoana kindOf Animal
BMW33 isA Auto
Δ
{ha, bi,…} ⊆ Δ × Δ
a
b
Modelul
Caty drives BMW33
formalizare (Sean Bechhofer, 2004)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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Un vocabular este o multime de nume utilizatein cadrul lumii modelate{ Tux, Pinguin, Animal, Caty, Persoana, Auto, drives,... }
formalizare
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
formalizareIntelesul constringerilor (Enrico Franconi, 2003):
relatia de tip isA: AreaManager⊆ Managerdisjunctia claselor: AreaManager ∩ TopManager = ∅Manager⊆ AreaManager ∪ TopManager
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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formalizareIntelesul relatiilor (Enrico Franconi, 2003):
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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formalizareIntelesul cardinalitatilor (Enrico Franconi, 2003):
multimea tuturorinstantelor
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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O interpretare I a vocabularului e un tuplu h Δ, ·I idomeniul e reprezentat de multimea Δasocierea dintre sintaxa si semantica este data de ·I numele obiectelor asociate elementelor lui Δnumele predicatelor unare (clase/concepte) asociate submultimilor lui Δnumele predicatelor binare (proprietati/roluri) asociate submultimilor Δ × Δsimilar, pentru aritati superioare – daca exista
formalizare
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
formalizare
Ontologiile modeleaza in special claseformeaza terminologiace trebuie sa fie adevarat in legatura cufiecare concept din cadrul ontologieiformal, TBox – terminology box (schema)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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formalizare
Ontologiile ofera un mecanism limitat deexprimare a indivizilor (instante ale claselor)descrierea indivizilor se poate faceprin baze de date, triple (RDF) etc.formal, ABox (datele)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
formalizare
Din punct de vedere computational,rationamentele privitoare la indivizisunt intractabile in generalin ipoteza lumilor inchise (closed worlds),negatia reprezinta esec – cazul bazelor de date
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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formalizare
Semantica formala este data de logicile descrierii(description logics) – detalii in (F. Baader et al., 2003)parti decidabile din logica de ordin I (FOL)constructori pentru definirea de concepte si roluri(eventual, pe baza celor deja existente)pot fi exprimate axiome specificind fapte despre concepte(clase), roluri (proprietati) si indivizi (instante)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
formalizare: reasoning
Pun la dispozitie sisteme de inferenta (reasoners)proceduri sound & complete pentru luarea deciziilorprivind anumite problemepot fi deduse constringeri suplimentaree.g., o entitate e sub-entitate a alteia, in cazul in carecea de a doua reprezinta o submultime a primei entitati
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
formalizare: reasoning
Implementari optimizate:Cerebra, DLP, FaCT++, Pellet, Racer,…www.cs.man.ac.uk/~sattler/reasoners.html
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logics
Familie de formalisme logicepentru reprezentarea cunostintelorcea mai simpla DL este ALC (inchisa propozitional)Attributive Language with Complements
AL introdus de (Schmidt-Schauß & Smolka, 1991)concepte construite folosind booleeni u, t, ¬plus cuantificatorii ∃, ∀rolurile (proprietatile) pot fi atomice
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Exemplu: “tatii fericiti” (Ian Horrocks, 2004)HappyFather≡Man u
∃ hasChild.Female u ∃ hasChild.Male u ∀ hasChild.(Rich t Happy)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics – extensii
S proprietatile sunt tranzitiveH ierarhia proprietatilor – e.g., hasDaughter v hasChild
O nominali/singletons – e.g., { Tux }I proprietati inverse – e.g., isChildOf≡ hasChild–
N restrictii de cardinalitate – e.g., >2 hasChild, 63 hasChildQ restrictii de cardinalitate calificate – e.g., >2 hasChild.MaleF restrictii de cardinalitate functionale – e.g., 61 hasMotherspecii DL
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
vezi Evgeny Zolin – http://www.cs.man.ac.uk/~ezolin/dl/
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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Knowledge Base
TBox (schema)
ABox (data)
Man ≡ Human u Male
HappyFather ≡ Man u∃ hasChild.Female u …
Radu : HappyFather
hRadu, Andreeai : hasChild
Infe
ren
ce S
yste
m
Inte
rfac
e
description logics
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Se ofera posibilitatea exprimarii:cardinalitatii: >3 hasClient, 61 hasMotherrestrictiilor de numar calificate: 61 hasParent.Malenominalilor (singletons) – constante: { CursSemWeb }domeniilor de valori concrete: areAni.(>18)tipurilor de proprietati – inversa, tranzitiva, compusa:hasMoney ◦ hasFame
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logics
Baza de cunostinte (KB) e compusa din2 multimi de axiome:TBox descrie structura domeniului (schema conceptuala)Elefant v Animal u Ierbivor u GriHappyFather ≡ Man u ∃hasChild.Female u …transitive (rudaCu)ABox descrie o situatie concreta (datele, instantele)Radu: HappyFather<Radu, Andreea>: hasChild
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Remarca:aceasta separatie nu are neaparato semnificatie logica, dar este convenabilaatit din punct de vedere conceptual,cit si din cel al implementarii
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logicsPentru OWL DL, modelul formal este specificatde logica descriptiva SHIQechivalenta cu SHOIN(Dn) OWL DL ≈ SHIQ extinsa cu nominali – i.e., SHOIQOWL Lite≈ SHIQ cu doar restrictii functionale – SHIFa se vedea lucrarile lui Ian Horrocks:www.cs.man.ac.uk/~horrocks/
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logicsPentru OWL, constructorii DL sunt:
Se permite si folosirea tipurilor de date XML Schema: ∃ areAni.byte
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DL versus OWL
OWL Full OWL DL OWL Lite
Se permite“orice”.
DefinitiileRDFS
se pot mixacu celeOWL
Nu se poate folosiowl:cardinality pentru
TransitiveProperty.O ontologie OWL DL
ontology nu poate importauna OWL Full.
Nu se poate defini o clasaca membra a alteia.
FunctionalProperty siInverseFunctionalPropertyse pot utiliza doar pentru
ObjectProperty
Se mentin restrictiile OWL DL plus: owl:minCardinality si
owl:maxCardinality nu se pot utiliza. Pentru owl:cardinalityvalorile permise sunt 0 si 1.
Nu se pot folosi: owl:hasValue,owl:disjointWith, owl:oneOf,
owl:complementOf si owl:unionOf
ne-decidabila
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Interpretari: I = (ΔI, ·I), unde:ΔI reprezinta domeniul (multime nevida)
·I este functia de interpretare asociind:conceptului (clasei) C → submultimea CI a lui ΔI
rolul (proprietatea) R→ relatia binaraRI peste ΔI
individului (instantei) i→ iI element al lui ΔI
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logicsFunctia de interpretare poate fi extinsala expresii privitoare la concepte:
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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O ontologie OWL se poate asociaunei baze de cunostinte DL notata K = hT , AiT (TBox) multime de axiome de forma:
CvD (incluziunea conceptelor)C≡D (echivalenta conceptelor)Rv S (incluziunea rolurilor)R≡ S (echivalenta rolurilor)R+ v R (tranzitivitatea rolurilor)
A (ABox) multime de axiome de forma:x ∈ C (instantierea unui concept)hx, yi ∈R (instantierea unui rol/proprietati)
description logics
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Exemplu de TBox (Ian Horrocks, 2005):description logics
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Exemplu de ABox (Ian Horrocks, 2005):description logics
O ontologie OWL e echivalenta cu o baza de cunostinte DL (TBox + ABox)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logicsAxiomele TBox sunt de doua tipuri:“Definitii”C v D sau C≡ D, unde C reprezinta un nume de conceptAxiome privitoare la incluziunea conceptelorgenerale (General Concept Inclusion – GCIs)
C v D unde C este un concept arbitrar
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logicsO interpretare I satisface (modeleaza) o axioma A(I ² A) daca:I ²C v D iff CI⊆DI I ²C≡D iff CI = DI
I ²R v S iff RI⊆ SI I ²R≡ S iff RI = SI
I ²R+ v R iff (RI)+⊆RI
I ² x ∈D iff xI ∈DI
I ² hx, yi ∈R iff (xI,yI) ∈RI
TB
oxA
Box
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logicsDefinitii privind satisfiabilitatea:I satisface multimea TBox T (I ² T )
iff I satisface orice axioma A din TI satisface multimea ABox A (I ²A) iff I satisface orice axioma A din A
I satisface baza de cunostinte K (I ²K) iff I satisface si T si A
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Cunostintele sunt semnificative (meaningful)clasele pot avea instante:conceptul C este satisfiabil in ceea ce priveste K iffexista un anumit model I al lui K astfel incit CI ≠ ∅
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Cunostintele sunt corecte – modeleaza intuitiile:C subsumeaza D (C v D) in ceea ce priveste K iffpentru orice model I al lui K, CI⊆DI
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Cunostinele sunt minimal redundante– nu exista sinonime nedorite:C este echivalent cu D (C≡D) in ceea ce priveste K iffpentru orice model I al lui K, CI = DI
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Interogarea cunostintelor:x este o instanta a conceptului C in ceea ce priveste K iffpentru orice model I al lui K, xI ∈CI
hx, yi este o instanta a rolului R in ceea ce priveste K iffpentru orice model I al lui K, (xI, yI) ∈RI
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logics
Aspectele de mai sus sunt reductibile la consistenta bazei de cunostinteo baza de cunostinte K este consistenta iffexista un anumit model I al lui K
consistenta bazei de cunostinte este reductibila laconsistenta conceptelor (concept consistency)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logicsVerificarea formala a consistenta este utila pentruproiectarea & mentenanta de ontologii:semnificative – toate clasele pot avea indivizi
corecte – exprima intuitiile expertilor domeniuluiminimal redundante – nu exista sinonime nedoriteaxiomatizate – exista (suficiente) descrieri detaliateoferirea de raspunsuri privind clasele/indivizii:gasirea claselor mai generale/particulareextragerea de indivizi conform unei interogari date
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Pentru verificarea satisfiabilitatii (consistentei) se utilizeaza algoritmi de tip tablou(tableaux algorithms)Francesco M. Donini & Fabio Massacci, 2000Jan Hladik & Jörg Model, 2004Ian Horrocks & Ulrike Sattler, 2005
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logicsDat fiind un concept C, se incearca a se construi un model(exemplu concret) arborescent consistent cu axiomeledin baza de cunostinte (faptele de baza din ABox)Conceptul C este descompus la nivel sintactic – se folosescconceptele complexe si axiomele din Tboxse aplica regulile de expandare a tabloului(tableau expansion rules)se infereaza constringerile asupra elementelor modelului
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Regulile de tip tablou corespund constructorilor din logicade exemplu, u, t etc.unele reguli sunt nedeterministe – e.g., t, 6in practica, aceasta inseamna cautare
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
Ne oprim cind nu mai pot fi aplicate reguli oriapare un conflict (clash)conflictul reprezinta o contradictie evidentae.g.: A(x), ¬ A(x)pentru terminare, poate fi necesaraverificarea ciclurilor (blocarea – blocking)
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics
C este satisfiabil iff regulile pot fi aplicate astfel inciteste construit un arbore complet expandat fara conflicte
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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Person u ∀hasChild.(Teacher t ∃hasChild.Teacher)<owl:Class><owl:intersectionOf rdf:parseType="Collection"><owl:Class rdf:about="#Person"/><owl:Restriction><owl:onProperty rdf:resource="#hasChild"/>
<owl:toClass rdf:resource="#TeacherWithChildTeacher"/></owl:Restriction></owl:intersectionOf></owl:Class>
<owl:Class rdf:ID="TeacherWithChildTeacher"><owl:unionOf rdf:parseType="Collection"><owl:Class rdf:about="#Teacher"/>
<owl:Restriction><owl:onProperty rdf:resource="#hasChild"/><owl:hasClass rdf:resource="#Teacher" />
</owl:Restriction></owl:unionOf>
</owl:Class>
description logics – exemplu
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
Person u ∀hasChild.(Teacher t ∃hasChild.Teacher)<owl:Class><owl:intersectionOf rdf:parseType="Collection"><owl:Class rdf:about="#Person"/><owl:Restriction><owl:onProperty rdf:resource="#hasChild"/>
<owl:toClass rdf:resource="#TeacherWithChildTeacher"/></owl:Restriction></owl:intersectionOf></owl:Class>
<owl:Class rdf:ID="TeacherWithChildTeacher"><owl:unionOf rdf:parseType="Collection"><owl:Class rdf:about="#Teacher"/>
<owl:Restriction><owl:onProperty rdf:resource="#hasChild"/><owl:hasClass rdf:resource="#Teacher" />
</owl:Restriction></owl:unionOf>
</owl:Class>
description logics – exemplu
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
Person u ∀hasChild.(Teacher t ∃hasChild.Teacher)<owl:Class><owl:intersectionOf rdf:parseType="Collection"><owl:Class rdf:about="#Person"/><owl:Restriction><owl:onProperty rdf:resource="#hasChild"/>
<owl:toClass rdf:resource="#TeacherWithChildTeacher"/></owl:Restriction></owl:intersectionOf></owl:Class>
<owl:Class rdf:ID="TeacherWithChildTeacher"><owl:unionOf rdf:parseType="Collection"><owl:Class rdf:about="#Teacher"/>
<owl:Restriction><owl:onProperty rdf:resource="#hasChild"/><owl:hasClass rdf:resource="#Teacher" />
</owl:Restriction></owl:unionOf>
</owl:Class>
description logics – exemplu
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logics – exemplu
Reprezentarea grafica (Altova SemanticWorks):
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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description logics – exemplu
Specificarea grafica a unei ontologii (Franconi, 2003):
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Dr. Sabin Buraga http://www.purl.org/net/busaco
Semantic Web <?xml version=“1.0” ?><curs desc=“…” />
description logics – exemplu“Rescrierea” in termeni logici:
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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concluzii
Implementarile actuale bazate pe OWL DL beneficiaza de cercetarile din domeniul logicilor descrierilor:semantici bine-definiteproprietati formale intelese in profunzime(complexitate, decidabilitate)algoritmi de rationament automat eficientisisteme de reasoning avind implementari optimizate
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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Rezumat
Logicile descrierii:fundamente, caracterizare,
baze de cunostinte
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Dr. Sabin Buraga http://www.purl.org/net/busaco
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?