Analyzing Theme, Space and Time: An Ontology- based Approach Matthew Perry, Farshad Hakimpour, Amit Sheth 14 th International Symposium on Advances in Geographic Information Systems, Arlington, VA, Nov. 10 – 11, 2006 knowledgement: NSF-ITR-IDM Award #0325464 ‘SemDIS: Discovering Complex Relationships in the Semantic Web’
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Analyzing Theme, Space and Time: An Ontology-based Approach Matthew Perry, Farshad Hakimpour, Amit Sheth 14 th International Symposium on Advances in Geographic.
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Analyzing Theme, Space and Time: An Ontology-based
ApproachMatthew Perry, Farshad Hakimpour, Amit Sheth
14th International Symposium on Advances in Geographic Information Systems, Arlington, VA, Nov. 10 – 11, 2006
Acknowledgement: NSF-ITR-IDM Award #0325464 ‘SemDIS: Discovering Complex Relationships in the Semantic Web’
• What is an ontology?– Agreed-upon formalization (or conceptual model) of
concepts and relationships in the real world
• Types of ontologies?– General-purpose vs. Domain ontologies
• Parts of an ontology– Classes – types or logical groups of objects– Relationships – how objects relate to each other– Attributes –features and characteristics of objects– Instances – members of Classes who have Attributes and
participate in Relationships
Background (ontologies and RDF/S)
Schema e.g. Student attends University
Data e.g. ‘Matt’ attends ‘University of Georgia’
Representing ontologies and instance data• W3C standards
– Resource Description Framework (RDF)• Language for representing information about
resources• Resources are identified by Uniform Resource
Identifiers (URIs) – globally-unique• Common framework for expressing information
From thematic analytics to spatio-temporal, thematic (STT) analytics (Ex: Bioterrorism)
E5:Terrorist
E6:Attack
E4:Chemical
E10:Doctor
E9:Base
E8:Soldier
E7:Platoon
E1:Soldier
E3:Disease
E2:Symptom
E14:Battle
E12:Platoon
E13:Soldier
E11:Location
assigned_to
participated_in
member_of
carried_out
spotted_at
stationed_at
member_of
sign_ofparticipated_in
causes
member_of
used_in
exhibits
Near in Space
After the Battle [4, 6]
[8, 10]
[0, 10]
[3, 5]
[0, 2]
[0, 2]
Spotted Before and Close in Time
Goals and Assumptions
Goals and Contributions of this work• Define a Domain-independent Ontology which
integrates Spatial and Thematic Knowledge– Allows exploiting the flexibility and extensibility of
Semantic Web data models– Can deal with incompleteness of information on the web
• Incorporate temporal metadata into this model• Identify and formalize basic spatial and temporal
relationship-based query operators which complement current thematic operators of SemDis
Assumptions / Design Decisions• Interested in Relationship Analysis• Do not address issues of scale and
granularity at this time• Exact serialization/representation of
spatial geometry is not a primary concern– RDF XML Literal Type (GML)– Ontology mirroring GML/OGC specification
Our Approach
Upper-level Ontology modeling Theme and Space
OccurrentContinuant
Named_PlaceSpatial_OccurrentDynamic_Entity
Spatial_Region
Occurrent: Events – happen and then don’t existContinuant: Concrete and Abstract Entities – persist over timeNamed_Place: Those entities with static spatial behavior (e.g. building)Dynamic_Entity: Those entities with dynamic spatial behavior (e.g. person)Spatial_Occurrent: Events with concrete spatial locations (e.g. a speech)Spatial_Region: Records exact spatial location (geometry objects,
coordinate system info)
occurred_at located_at
occurred_at: Links Spatial_Occurents to their geographic locationslocated_at: Links Named_Places to their geographic locations
rdfs:subClassOfpropertyFinal Classification of Domain
Classes depends upon the intendedapplication
OccurrentContinuant
Named_Place
Spatial_OccurrentDynamic_Entity
PersonCity
Politician
Soldier
Military_Unit
BattleVehicle
Bombing
Speech
Military_Eventassigned_to
on_crew_of
used_in
gives
participates_in
trains_at
Spatial_Region
located_at occurred_at
Upper-level Ontology
Domain Ontology
rdfs:subClassOf used for integrationrdfs:subClassOfrelationship type
Incorporation of Temporal Information• Use Temporal RDF Graphs defined by
Gutiérrez, et al1
• Focuses on absolute time and considers time as a discrete, linearly-ordered domain
• Associate time intervals with statements which represent the valid-time of the statement– Essentially a quad instead of a triple
1. Claudio Gutiérrez, Carlos A. Hurtado, Alejandro A. Vaisman: Temporal RDF. ESWC 2005: 93-107
Example Temporal Graph: Platoon Membership
E1:Soldier
E3:Platoon E5:Soldier
E2:Platoon
E4:Soldier
assigned_to [1, 10]
assigned_to [11, 20]
assigned_to [5, 15]
assigned_to [5, 15]
Querying in the STT dimensions• Path Query in the thematic dimension
– Thematic Context
• Associate spatial region with a path• Associate temporal interval with a path• Query operators based on properties and
relationships between associated spatial regions and temporal intervals
Thematic Context• Specifies a type of connection between resources in the thematic
ANS ρ-temporal_intersect (ρ-spatial_eval (S1, S2, distance (S1, S2) 10 miles)
Spatiotemporal Relationship QueriesExample: When did the 101st Airborne Division come within 10 miles of the 1st Armored Division in the context of Battle participation
Conclusions• Defined Basic Domain-independent ontology
integrating Theme and Space and showed how to incorporate temporal information with temporal RDF graphs
• Novelty centers on utilization of named relationships in the thematic dimension
• Link non-spatial entities with spatial entities at the thematic level in order to analyze their spatial properties
• Allows us to take advantage of the flexibility and extensibility of RDF and helps cope with incompleteness of information on the Web