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NeOn, Rome, 21 Mar 2006 JSI 3 Overview Formalizing context Cyc Semantic Web C-OWL Probabilistic approaches JSI related work
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Context sensitivity for networked ontologies
Igor Mozetič, Marko Grobelnik, Damjan BojadžijevJozef Stefan InstituteSlovenia
NeOn, Rome, 21 Mar 2006
JSI 2
text context
explicit implicit
global local
text
I’m here who, where
text expl(context)
text_1context_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]
AI SWscope, 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
Ontologies Contexts
Global, shared modelEncode common viewCombining by import
Global semantics
Local modelsEncode each party’s viewCombining by explicit mappingsLocal Models Semantics
NeOn, Rome, 21 Mar 2006
JSI 9
OWL: Global semantics for multiple (networked) ontologies
sharedmodel
NeOn, Rome, 21 Mar 2006
JSI 10
OWL: Global semantics for multiple (networked) ontologies
sharedmodel
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
contextualizedontology
context
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 meets
starts finishes
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 meets
starts finishes
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 meets
starts finishes
day(now)day(now-1) meets
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 meets
starts finishes
day(now)day(now-1) meets
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 meets
starts finishes
day(now)day(now-1) meets
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 meets
starts finishes
day(now)day(now-1) meets
meets
equals
day(now+1)meets
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 meets
starts finishes
day(now)day(now-1) meets
meets
equals
day(now+1)meets
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
wee
k m
onth
ye
ar
deca
de
now = ?
context
NeOn, Rome, 21 Mar 2006
JSI 25
News analysis
earthquake tsunami tsunami tsunami tsunami
News stream:
the same? yet another one?
NeOn, Rome, 21 Mar 2006
JSI 26
A temporal model: Tsunami
Earthquake
Tsunami
Search & Rescue Rebuilding
~minutes
~hours
~days ~months
E T 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
earthquake tsunami tsunami tsunami tsunami
News stream:
model of tsunami
provides contextfor subsequentevents
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