Research Activity including Geographical Ontology Modules for Efficient Semantic Web Reuse

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Research ActivityincludingGeographical
Ontology Modules forEfficient Semantic Web Reuse

• David George, University of Central Lancashire

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Research Activities

• Semantic Heterogeneity
• Structural and Semantic discrepancies in database
  conceptualisation and development
• Data and Information Integration
• Federated Databases
• Mediators Global-as-View, Local-as-View
• Information Brokering Systems and use of Ontology
• Semantic Web and Ontology
• Practical interaction with Semantic Web
  Technologies
• Protégé, FaCT, SWOOP, and Jena API Toolkit

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Research Activities

• Development of Jena-based Java Browser Interface
  inc
• Reading OWL and querying SPARQL
• RDF storage in MySQL
• Foundation Ontology SUMO, DOLCE, CyC, BFO (Snap
  and Span)
• Design Best-Practice Modularity in Ontology
  development (Rector, 2003)
• Experimentation with small-scale OWL ontologies
• Formal Concept Analysis - using Concept Explorer

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Structural Semantic Heterogeneity

• Abstraction Level Conflicts
• generalisation/specialisation/aggregation
• Schematic Discrepancies
• Objects represented differently
• Data, attributes, entity
• Entity Definition Conflicts
• naming conflicts (synonyms and homonyms)
• database identifier conflicts e.g. id v. name
• Data Value Conflicts
• temporal Inconsistency (last update)
• data representation (integer v.
  string/precision/scale)

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Data Integration
Global Domain Agreements
Knowledge
Digital media Visual/Spatial/Temporal
Data Kiosk/Geographic/Flights/Forecasting
Focus Semantics Domain-specific
Information
Structured, Semi-structured Text repositories
Data
Structured DBs, Files
Focus Systems Communications
System
Virtual Integration Single Ontologies
Multiple ontologies, Inter-ontological
Schema Integration Common Data Models
Local Task Schemas
Federated DBS
Federated IS (inc Mediators)
Information Brokering
1985
1995
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Jena Toolkit OWL interface
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SPARQL Query Interface
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MySQL interface
Persistence in RDF triple storage
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Ontology Specification Best Practice

• Ontology elements can be described as

• Primitives self-standing entities
  (objects/forms) e.g. Structure, Process, System,
  Organisation

• Relations concept-linking properties e.g. X
  hasForm Y, hasRole

• Roles functions e.g. RailTransportRole

• and
• Definables dependent concepts defined by
  combining Primitives, Relations, and Roles

RailwayBridge Bridge ? (hasForm ? Structure ?
hasRole ? RailTransportRole)
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Formal Concept Analysis

• Using Concept Explorer
• Examined how Concept Analysis may be useful in
  identifying Classes and Instances in database
  tables
• Considered structural heterogeneity
• Classes represented by single entity (table)
• Classes represented by table joins
• Classes as subset of table records
• Instances represented by entity, attribute, data
  (record)

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Formal Concept Analysis
Example Classes represented by table joins
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Formal Concept Analysis
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Creating Geographical Ontology Modules
forEfficient Semantic Web Reuse
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Role of Semantic Web Ontology

• Conceptualise and convey a domain of interest.
• Agree and provide a vocabulary of terms to
  portray the hierarchical or taxonomic structure
  and the relationships and constraints.
• Serve as a vehicle to semantically link, or
  integrate, information across the Web.
• Facilitate information reuse by consistency of
  terms and fitness-for-purpose.

suitable for how it is going to be used
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Ontology and Integration

• Ontology Reuse is a key Integration benefit (Noy
  and Hafner, 1997 ).
• Ontology development still at a stage where
  little interchange between organisations?
• Merger, Alignment and Mapping complexity issues
  with Integration.
• Developer reluctance easier to re-invent own
  local ontology than reuse.
• Reuse of an external ontology will likely result
  in descriptive and structural irrelevances.
• Smaller component ontology modules improvised as
  required may encourage wider usage/take-up

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Ontology Integration

• Possible Ontology On Objectives
• Merger OA OB ? OC
• Alignment OA OB OC
• Mapping a virtual integration where OA, OB and
  OC concepts are semantically related.
• Methods
• 1 and 2 are achieved by rewriting
  (reformulation).
• Original ontologies are subsumed or made
  consistent (respectively).
• 3 is achieved by mappings between concepts of
  imported ontologies. A, B and C endure
  autonomously.
• Ontology Reuse, in this presentation, refers to
  3 Mapping.

(Pinto et al., 1999, Noy and Musen, 1999, de
Bruijn et al., 2004, Visser and Tamma, 1999,
Kalfoglou and Schorlemmer, 2003, Ding et al.,
2002)
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Reuse through Ontology Mapping
(Ding and Foo, 2002)

• Concept mappings achieved through various syntax
  options

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1 - Informal specific Class Reuse

• Using namespace declaration to explicitly specify
  a single external concept, e.g.

ltrdfRDF xmlns"http//www.livewiredg.myby.co.uk/
rdf/geo-layers/rail.owl" xmlnscyc"http//w
ww.cyc.com/2003/04/01/cyc" gt ltowlClass
rdfabout"cycTransportationCompany"/gt
ltowlClass rdfID"RailOperator"gt
ltrdfssubClassOf rdfresource"RailwayComponent"/
gt ltrdfssubClassOf rdfresource"cycTran
sportationCompany"/gt lt/owlClassgt ..

• How would an agent understand the Cyc context of
  the superclass of cycTransportationCompany

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2 - Formalised specific Class Reuse
ltrdfRDF xmlnsglobal"http//www.livewiredg
.myby.co.uk/rdf/geo-layers/global.owl"
xmlnshttp//www.owl-ontologies.com/flight.owl
..gt ltowlClass rdfaboutglobalArtifact"/gt
ltowlClass rdfID"Helicopter"gt
ltrdfssubClassOfgt ltowlRestrictiongt
ltowlonPropertygt ltowlLinkProperty
rdfabout"hasForm"/gt lt/owlonPropertygt
ltowlsomeValuesFrom rdfresource"globalA
rtifact"/gt lt/owlRestrictiongt
lt/rdfssubClassOfgt lt/owlClassgt
ltowlLinkProperty rdfID"hasForm"gt
ltowlforeignOntology rdfresource"global"/gt
ltrdfsdomain rdfresource"Helicopter"/gt
ltrdfsrangegt ltowlforeignClass
rdfabout"globalArtifact"gt
ltowlforeignOntology rdfresource"global "/gt
lt/owlforeignClassgt lt/rdfsrangegt
lt/owlLinkPropertygt

• E-Connections
• Representation and reasoning with foreign
  ontologies (Grau et al, 2006)
• Allows specific concept linking. Few tools
  available e.g. SWOOP (OWL Ontology Editor)

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3 - Modularity by sub-domain separation

• SWOOP permits ontology partitioning (module
  extraction)

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4 - Class reuse by Ontology Import
Objective Map Rail Ontology class
RailOperator to Cyc Ontology class
TransportationCompany
Action Import Opencyc into Rail gt
6.8MB Effect Adds 2843 classes 1256
properties load time 1.5 to 7.5 mins Protégé out
of memory
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Alternative Reuse approach?

• Consider the way Ontologies conceptualised and
  developed?
• Break down domain ontologies into sub-domains
  (modules)
• Try to achieve disjoint structures minimise
  redundancy
• Can be demonstrated using Geographical context
• Geographical concepts interface with virtually
  every aspect of daily life and feature
  prominently in information management systems.
• Geographical ontologies offer a logical vehicle,
  to examine how modules can be specified
  efficiently and effectively.

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Efficient and Effective Context

• Efficient
• Minimise rework
• i.e. having to update a specification whereas
  stability contributes to reusability.
• Developing durable ontologies focus on
  permanence of terms and essentiality.
• Minimise redundancy
• avoiding duplication of terms reduce mappings.
• Minimise query complexity and processing
  overhead.
• Effective
• Using a consistent best practice approach
• Accurately and meaningfully describing concepts
  their relationships and constraints (Rector et
  al, 2003).
• Create small building blocks small ontological
  components serving as utility pieces.

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PC and Ontology Analogy

• Adding a component to a PC
• To enhance our own PC, we would not buy a
  complete PC with all components specified,
• It would require dismantling and refitting some
  parts may not be compatible
• Result additional, unnecessary and costly extra
  work.
• Accepted Protocol
• Build our requirement from small, interchangeable
  components
• Preferably with multiple PC compatibility.

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Ontological Inefficiency

• Potential redundancy
• Vulnerability to change
• How relevant are they?

• Ontology Reuse - Imports
• E.g. if OTN 1 is imported what do we see?
• Ontology much smaller than Cyc, but still
  multiple sub-domains

• Only for an application that uses ALL concepts

1 OTN - Ontology of Transportation Networks
(Lorenz et al, 2005)
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How could we quantify Import issues?

• Possible Import Inefficiency Metrics
• Filesize OA OB
• Classes OA OB
• Relevance OA OB
• Load Time OA (OA OB)
• Ontology Durability (or Permanence) OB
• How well specified is it, in terms of quality of
  constraints / definition?

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Ontology Permanence
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Ontology Permanence
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Geographic Ontology Modules

• How might we approach developing a modular
  ontology set?
• Previously discussed considering map layers
• No scientific justification for this - but offers
  a conceptual discipline that could be exploited
  for our purposes
• Example consider a LandTransport ontology ..

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Transport Ontology

• Applications
• Passenger services
• Freight services
• Tourism
• Strategic route planning and development
• Infrastructure planning and disaster management
• Environment and Energy waste, pollution, traffic
  volumes, resource consumption.

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Ontology Geo-Modules
Geo-Modules
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Land Transport
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Transport Interchange

• multimodal road-rail
• within a town, service facility

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Visualising Our Transportation Domain
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Rail Transport Ontology
Q rename LevelCrossing ? RoadCrossing? But we
dont do Roads in Rail!
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Road Transport Ontology
Q reclassify ChannelTunnelTerminal ? Road
Concept? But we dont do Rail in Roads!
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PopulationGroup Ontology
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LandTransport Ontology
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LandTransport Import Consequences

• We would need to import Road, Rail,
  PopGroups into LandTransport
• For just Road and Rail it results in
  duplications and redundancy

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Revisualisation Transportation Layers
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How do we develop Geo-Modules

• Need to de-integrate to allow low-cost
  integration
• Aim towards effectively disjoint domains
• Deliver by removing concept duplication between
  modules redundancy
• Need to promote/relegate multi or single-context
  concepts and relations

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Transportation Domain Layers
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Development Issues

• Document scope of ontology purpose and
  requirements
• Consider how to visualise for Conceptual Design
• Document concept and relation definitions
• Develop/specify to conceptual design and
  definitions
• Iteration does it meet requirements
• Incorporate context parameters for ontology
• Elevation and Relegation to reduce redundancy in
  reuse

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Modular Ontology ve/-ve

• Advantages
• Small is manageable
• Select only required building block modules
• Independent therefore less vulnerable to change
• Change is isolated to the module and subsuming
  domain?
• Disadvantages
• Increased mappings?
• Needs to be examined

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References
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