Context sensitivity for networked ontologies Igor Mozetič, Marko Grobelnik, Damjan Bojadžijev Jozef Stefan Institute Slovenia

NeOn, Rome, 21 Mar 2006 JSI 2 text context explicitimplicit globallocal text I’m here who, where textexpl(context) text_1 context_1 +

NeOn, Rome, 21 Mar 2006 JSI 3 Overview Formalizing context Cyc Semantic Web C-OWL Probabilistic approaches JSI related work

NeOn, Rome, 21 Mar 2006 JSI 4 McCarthy [1993] AI: modelling of context and use in automated reasoning implicit -> explicit ist( context, proposition ) context = collection of assumptions (generalization of, partially known) entering and exiting, nesting, lifting, transcending, …

NeOn, Rome, 21 Mar 2006 JSI 5 Cyc [Lenat, Guha] Cyc KB = set of microtheories (Mt) Microtheory = set of axioms  shared assumptions, topic  internally consistent  localized (more efficient) reasoning  preconditions = context in which Mt is applicable

NeOn, Rome, 21 Mar 2006 JSI 6 Cyc (example) ist( NaiveStateChangeMt, isa( ?X, Freezing ) & outputsCreated( ?X, ?Obj ) => stateOfMatter( ?Obj, SolidStateMatter )) NaiveStateChangeMt domainAssumptions: forAll ?U isa( ?U, StateOfMatterChangeEvent ) => isa( ?U, CreationOrDestructionEvent )

NeOn, Rome, 21 Mar 2006 JSI 7 Context for Semantic Web [Guha et al] AISW scope, complexity of phenomena scale (comp. complexity), distributed sources, ease of use Aggregation from different sources. Issues: class differences property type differences point of view implicit time approximations

NeOn, Rome, 21 Mar 2006 JSI 8 C-OWL [Giunchiglia et al]: Contextualizing ontologies OntologiesContexts Global, shared model Encode common view Combining by import Global semantics Local models Encode each party’s view Combining by explicit mappings Local Models Semantics

NeOn, Rome, 21 Mar 2006 JSI 9 OWL: Global semantics for multiple (networked) ontologies shared model

NeOn, Rome, 21 Mar 2006 JSI 10 OWL: Global semantics for multiple (networked) ontologies shared model import

NeOn, Rome, 21 Mar 2006 JSI 11 C-OWL: Local model semantics local models

NeOn, Rome, 21 Mar 2006 JSI 12 C-OWL: Mappings contextualized ontology context

NeOn, Rome, 21 Mar 2006 JSI 13 C-OWL ontology is a pair: OWL ontology (target):  concepts  individuals  roles mappings (bridge rules):   equivalence   onto   into   compatible   incompatible

NeOn, Rome, 21 Mar 2006 JSI 14 C-OWL example OWL ontology (target) + mappings (bridge rules)

NeOn, Rome, 21 Mar 2006 JSI 15 C-OWL of any use? Import ontology vs. define context mappings? (diversity as defect vs. feature) Semantic Web = Web of Semantic links ? (context mappings) Discovering context mappings = core issue in building Semantic Web ?

NeOn, Rome, 21 Mar 2006 JSI 16 JSI related work Parametric temporal ontology Simultaneous ontologies User profiling Implicit document context (links)

NeOn, Rome, 21 Mar 2006 JSI 17 Temporal ontology Temporal algebra [Allen]:  event = temporal interval  relations: before, meets, starts, finishes, … week(now) day(sun)day(mon)meets startsfinishes

NeOn, Rome, 21 Mar 2006 JSI 18 Temporal ontology Temporal algebra [Allen]:  event = temporal interval  relations: before, meets, starts, finishes, … week(now)week(now+1) day(sun)day(mon)meets startsfinishes meets

NeOn, Rome, 21 Mar 2006 JSI 19 Temporal ontology Temporal algebra [Allen]:  event = temporal interval  relations: before, meets, starts, finishes, … week(now)week(now+1) day(sun)day(mon)meets startsfinishes day(now) day(now-1) meets day(now+1)meets

NeOn, Rome, 21 Mar 2006 JSI 20 Temporal reasoning Temporal algebra [Allen]:  event = temporal interval  relations: before, meets, starts, finishes, … week(now)week(now+1) day(sun)day(mon)meets startsfinishes day(now) day(now-1) meets equals day(now+1)meets ?

NeOn, Rome, 21 Mar 2006 JSI 21 Temporal reasoning Temporal algebra [Allen]:  event = temporal interval  relations: before, meets, starts, finishes, … week(now)week(now+1) day(sun)day(mon)meets startsfinishes day(now) day(now-1) meets equals day(now+1)meets day(mon) starts

NeOn, Rome, 21 Mar 2006 JSI 22 Temporal reasoning Temporal algebra [Allen]:  event = temporal interval  relations: before, meets, starts, finishes, … week(now)week(now+1) day(sun)day(mon)meets startsfinishes day(now) day(now-1) meets equals day(now+1)meets day(mon) starts

NeOn, Rome, 21 Mar 2006 JSI 23 Temporal reasoning Temporal algebra [Allen]:  event = temporal interval  relations: before, meets, starts, finishes, … week(now)week(now+1) day(sun)day(mon)meets startsfinishes day(now) day(now-1) meets equals day(now+1)meets day(mon) starts equals

NeOn, Rome, 21 Mar 2006 JSI 24 Parameterized temporal ontology Parameters:  now  order of magnitude  past - future now-1 now now+1 now+2 day week month year decade now = ? context

NeOn, Rome, 21 Mar 2006 JSI 25 News analysis earthquaketsunami News stream: the same?yet another one?

NeOn, Rome, 21 Mar 2006 JSI 26 A temporal model: Tsunami Earthquake Tsunami Search & RescueRebuilding ~minutes ~hours ~days~months ET S&R 25.dec 26.dec 27.dec 28.dec 29.dec 30.dec 31.dec 1.jan 2.jan 3.jan

NeOn, Rome, 21 Mar 2006 JSI 27 News analysis: Temporal model = Context earthquaketsunami News stream: model of tsunami provides context for subsequent events

NeOn, Rome, 21 Mar 2006 JSI 28 Summary Parameterized ontology Context determines parameters  when?  how long?  order of magnitude Temporal model  selected by events  provides context