Context sensitivity for networked ontologies

1
Context sensitivity for networked ontologies

• Igor Mozetic, Marko Grobelnik, Damjan Bojadijev
• Jozef Stefan Institute
• Slovenia

2
text
text
context
explicit
implicit
global
local
Im here
who, where
context_1

3
Overview

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

4
McCarthy 1993

• AI modelling of context and use in automated
  reasoning
• implicit -gt explicit
• ist( context, proposition )
• context collection of assumptions
  (generalization of, partially known)
• entering and exiting,
• nesting, lifting, transcending,

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

6
Cyc (example)

• ist( NaiveStateChangeMt,
• isa( ?X, Freezing )
• outputsCreated( ?X, ?Obj )
• gt
• stateOfMatter( ?Obj, SolidStateMatter ))
• NaiveStateChangeMt domainAssumptions
• forAll ?U
• isa( ?U, StateOfMatterChangeEvent )
• gt
• isa( ?U, CreationOrDestructionEvent )

7
Context for Semantic Web Guha et al

• Aggregation from different sources. Issues
• class differences
• property type differences
• point of view
• implicit time
• approximations

8
C-OWL Giunchiglia et alContextualizing
ontologies
9
OWL Global semantics for multiple (networked)
ontologies
shared model
10
OWL Global semantics for multiple (networked)
ontologies
shared model
import
11
C-OWL Local model semantics
local models
12
C-OWL Mappings
context
context
contextualized ontology
13
C-OWL ontology is a pair

• OWL ontology (target)
• concepts
• individuals
• roles
• mappings (bridge rules)
• ? equivalence
• ? onto
• ? into
• ? compatible
• ? incompatible

14
C-OWL example

• OWL ontology (target) mappings (bridge rules)

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 ?

16
JSI related work

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

17
Temporal ontology

• Temporal algebra Allen
• event temporal interval
• relations before, meets, starts, finishes,

week(now)
starts
finishes
day(sun)
day(mon)
meets
meets
18
Temporal ontology

• Temporal algebra Allen
• event temporal interval
• relations before, meets, starts, finishes,

week(now)
week(now1)
meets
starts
finishes
day(sun)
day(mon)
meets
meets
19
Temporal ontology

• Temporal algebra Allen
• event temporal interval
• relations before, meets, starts, finishes,

week(now)
week(now1)
meets
starts
finishes
day(sun)
day(mon)
meets
meets
day(now-1)
day(now1)
meets
day(now)
meets
20
Temporal reasoning

• Temporal algebra Allen
• event temporal interval
• relations before, meets, starts, finishes,

week(now)
week(now1)
meets
starts
finishes
day(sun)
day(mon)
meets
meets
?
equals
day(now-1)
day(now1)
meets
day(now)
meets
21
Temporal reasoning

• Temporal algebra Allen
• event temporal interval
• relations before, meets, starts, finishes,

week(now)
week(now1)
meets
starts
finishes
starts
day(sun)
day(mon)
meets
meets
day(mon)
equals
day(now-1)
day(now1)
meets
day(now)
meets
22
Temporal reasoning

• Temporal algebra Allen
• event temporal interval
• relations before, meets, starts, finishes,

week(now)
week(now1)
meets
starts
finishes
starts
day(sun)
day(mon)
meets
meets
meets
day(mon)
equals
day(now-1)
day(now1)
meets
day(now)
meets
23
Temporal reasoning

• Temporal algebra Allen
• event temporal interval
• relations before, meets, starts, finishes,

week(now)
week(now1)
meets
starts
finishes
starts
day(sun)
day(mon)
meets
meets
meets
day(mon)
equals
equals
day(now-1)
day(now1)
meets
day(now)
meets
24
Parameterized temporal ontology

• Parameters
• now
• order of magnitude
• past - future

now ?
day week month year decade
context
now-1 now now1 now2
25
News analysis
News stream
the same?
yet another one?
26
A temporal model Tsunami

Search Rescue
Rebuilding
Earthquake
days
months
minutes
Tsunami
hours
E
T
SR
25.dec 26.dec 27.dec 28.dec 29.dec
30.dec 31.dec 1.jan 2.jan 3.jan
27
News analysis Temporal model Context
News stream
provides context for subsequent events
model of tsunami
28
Summary

• Parameterized ontology
• Context determines parameters
• when?
• how long?
• order of magnitude
• Temporal model
• selected by events
• provides context