1 where do spatial context-models end and where do ontologies start? a proposal of a combined...
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Where do spatial context-models end and where do ontologies start?
A proposal of a combined approach
Christian BeckerDistributed Systems
Daniela NicklasApplications of Parallel
and Distributed Systems
Universität Stuttgart, Germany
Center of Excellence 627:Spatial World Models for
Mobile Context-Aware Applications
University of StuttgartCenter of Excellence 627
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ContextManagement
Starting Point
Context-Aware Applications: adapt their behavior depending context need context management
2 approaches of context management: context models:
database-style: applications can select/query context information for adaptation
contextual ontologies: knowledge representation and deduction:
applications can define complex situations
University of StuttgartCenter of Excellence 627
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PhysicalWorld
ContextModel
Context Models
Applications
query (filter)
Update(id, value)
Sen
sors
(Fu
sion
)
Update(id, value)
Ap
pli
cati
on
Sta
te
University of StuttgartCenter of Excellence 627
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Location, identity, and time
properties of each spatial object
location and ID: primary access path for context used for selection:
What is there? (location)
What is John doing? (ID)
time: often implicit ("now") explicit for history and prognosis
combined with location or ID: who was here yesterday? (location + time)
where was I yesterday? (ID + time)
lost key
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Classification of Context Models
dynamics: low to high update rate
stationary vs. mobile objects/sensor values
spatial scope local to global
complexity of abstraction level of detail, #objects
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Shared Context Models
GIS
data integration,schema matching
S
S
SS
sensorfusion
Federation
query
query
Application
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Five tiers of spatial ontologies [Frank 2003]
Ontology Tier 0: Physical RealityOntology Tier 0: Physical Reality
Ontology Tier 1: Observable RealityOntology Tier 1: Observable Reality
Ontology Tier 2: Object WorldOntology Tier 2: Object World
Ontology Tier 3: Social RealityOntology Tier 3: Social Reality
Ontology Tier 4: Cognitive AgentsOntology Tier 4: Cognitive Agents
Inte
rpre
tatio
n
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Context Models and Contextual Ontologies
Ontology Tier 0: Physical RealityOntology Tier 0: Physical Reality
Ontology Tier 1: Observable RealityOntology Tier 1: Observable Reality
Ontology Tier 2: Object WorldOntology Tier 2: Object World
Ontology Tier 3: Social RealityOntology Tier 3: Social Reality
Ontology Tier 4: Cognitive AgentsOntology Tier 4: Cognitive Agents
Con
text M
od
els
Con
textu
al O
nto
log
ies
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Shared Context Models
GIS
data integration,schema matching
S
S
SS
sensorfusion
contextmodellayer
observationlayer
tier 1
tier 2
tier 3
Federation
query
federationlayer
query
Applicationtier 4
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A Combined Approach
Federation
Inference Machine, Reasoning
Rules
query
interpretation
Application
query
Application
GIS
data integration,schema matching
S
S
SS
sensorfusion
contextmodellayer
reasoninglayer
observationlayer
tier 1
tier 2
tier 3
tier 4
federationlayer
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Conclusion
context models: efficient management of large-scale context
contextual ontologies: support for reasoning
combined approach: select context based on context models
add semantic information and reason about selection
open questions how to represent semantic information? (Rules, ...)
consistency, coherence, data quality, trust, ...
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www.nexus.uni-stuttgart.de