SWSRuLE
Semantic Web Spatial Rule Language and Engine
Cardiff, November 2007
Geographic Ontologies
(Logical)
•
Logical theories (at least in computer science terms).
Exhaustive representation of a domain (Kashyap&shet 97).
Geographic domain in our case. Upper level ontologies
•
Geographic ontologies are a means of encoding geographic
concepts and their structure
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•
Popular representation using a Description Logic (OWLDL or OWL-Lite)
Heritage semantic networks and frame-based systems.
•
•
Object orientated paradigm
Logical semantics and therefore key inference
mechanisms
•
•
•
Subsumption reasoning
Satisfiability checking
Membership checking
Logical and Spatial Integrity
• Maintaining the logical as well as spatial integrity
of geographic ontologies is crucial for maintaining
their soundness and viability, in particularly when
acquiring information from different sources
Directional Inconsistency
Topological inconsistency
C
A
B
(a)
(b)
(a)
A
C
B
(b)
Integrity Example
Geo
names
Repo 2
Wikipedi
a
Integrity Example
Geo
names
Repo 2
Wikipedi
a
Boundary of Wales
Integrity Example
Geo
names
Repo 2
Wikipedi
a
South Glamorgan, longitude, latitude
Boundary of Wales
Integrity Example
Geo
names
Repo 2
Wikipedi
a
South Glamorgan, longitude, latitude
Boundary of Wales
Integrity Example
Geo
names
Repo 2
Wikipedi
a
South Glamorgan, longitude, latitude
Boundary of Wales - therefore South Glamorgan disjoint from Wales
Integrity Example
Geo
names
Repo 2
Wikipedi
a
South Glamorgan, longitude, latitude
Boundary of Wales - therefore South Glamorgan disjoint from Wales
South Glamorgan contains Cardiff
Integrity Example
Geo
names
Repo 2
Wikipedi
a
South Glamorgan, longitude, latitude
Cardiff part of wales (Geonames.org)
Boundary of Wales - therefore South Glamorgan disjoint from Wales
South Glamorgan contains Cardiff
Integrity Example
Geo
names
South Glamorgan, longitude, latitude
Cardiff part of wales (Geonames.org)
Contains and Inside --> {E,I,Cb,Ct,Cv,O}
Repo 2
Wikipedi
a
Boundary of Wales - therefore South Glamorgan disjoint from Wales
South Glamorgan contains Cardiff
•
•
Spatial reasoning rules for
deduction
•
Spatial (and non) integrity rules, to
maintain consistency of geographic
ontology
Rule layer well established alongside
semantic web ontologies (SWRL,
WRL,RuleML, DLP etc)
les
Rule expression over geographic
ontologies, enhance expressive power
of the ontology:
Ru
•
Rules for Geo-ontologies
OWL/RDF and Rules
RDF, sets of triples
<subject,predicate,object>
For example
<NS:Glamorgan, NS:Meets, NS:Gwent)
<NS:Glamorgan, NS:Type, NS:GeoFeature)
Horn rules with extra-logical extensions used to
capture OWL axioms:
(?x rdf:type ?y) and (?y rdf:type ?c) -> (?x rdf:type ?c)
Other rules possible, both deduction and integrity rules
Dealing Effectively with Geographic
Ontology Maintenance
Need to deal with:
• Spatial data types
• Large scale ontologies with many thousand geographical
features
• Maintaining the spatial integrity of the ontology during
transactions
• Error handling
• Error exceptions
• Incomplete spatial information
• Authoring rule sets
• Visualising the ontology, errors etc.
Geo-ontology Framework
• OWL ontology
component
• Location base
• Integrity and deduction
rule component
• Error ontology (base) for
storage and later retrieval
of errors
• Visual management
system
Demo