context sensitivity for networked ontologies igor mozetič, marko grobelnik, damjan bojadžijev...

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

+


JSI 3

Overview

Formalizing context Cyc Semantic Web C-OWL Probabilistic approaches JSI related work


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, …


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


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 )


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


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


JSI 9

OWL: Global semantics for multiple (networked) ontologies

sharedmodel


JSI 10

OWL: Global semantics for multiple (networked) ontologies

sharedmodel

import


JSI 11

C-OWL: Local model semantics

local models


JSI 12

C-OWL: Mappings

contextualizedontology

context

context


JSI 13

C-OWL ontology is a pair:

OWL ontology (target): concepts individuals roles

mappings (bridge rules): equivalence onto into compatible incompatible


JSI 14

C-OWL example

OWL ontology (target) + mappings (bridge rules)


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 ?


JSI 16

JSI related work

Parametric temporal ontology Simultaneous ontologies User profiling Implicit document context (links)


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


JSI 18

Temporal ontology


week(now) week(now+1)


starts finishes

meets


JSI 19

Temporal ontology




starts finishes

day(now)day(now-1) meets

meets

day(now+1)meets


JSI 20

Temporal reasoning




starts finishes


meets

equals

day(now+1)meets

?


JSI 21

Temporal reasoning




starts finishes


meets

equals

day(now+1)meets

day(mon)

starts


JSI 22

Temporal reasoning




starts finishes


meets

equals

day(now+1)meets

meets day(mon)

starts


JSI 23

Temporal reasoning




starts finishes


meets

equals

day(now+1)meets

meets day(mon)

starts

equals


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


JSI 25

News analysis

earthquake tsunami tsunami tsunami tsunami

News stream:

the same? yet another one?


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


JSI 27

News analysis: Temporal model = Context

earthquake tsunami tsunami tsunami tsunami

News stream:

model of tsunami

provides contextfor subsequentevents


JSI 28

Summary

Parameterized ontology Context determines parameters

when? how long? order of magnitude

Temporal model selected by events provides context

context sensitivity for networked ontologies igor mozetič, marko grobelnik, damjan bojadžijev...

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