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Ontology Modules by Layering. Facilitating Reuse in a Geographical Semantic Web Context. Ontology and Integration. A Semantic Web lift-off requires critical mass and/via wider acceptance. Ontology development still at a stage where little interchange between organisations?

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Ontology modules by layering

Ontology Modules by Layering

Facilitating Reuse in a Geographical Semantic Web Context

Ontology and integration
Ontology and Integration

  • A Semantic Web lift-off requires critical mass and/via wider acceptance.

  • Ontology development still at a stage where little interchange between organisations?

  • Ontology Reuse is a key Integration benefit.

  • Merger, Alignment and Mapping complexity issues when considering Integration.

Ontology and integration1
Ontology and Integration

  • Developer reluctance – easier to re-invent own dedicated local ontology specification than reuse.

  • Reuse of an external ontology will likely result in descriptive and structural irrelevances.

  • A move towards smaller component ontology modules – that can then be improvised as required – may encourage wider usage/take-up

Ontology integration
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.


  • 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.

Informal specific class reuse
“Informal” specific Class Reuse

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

<rdf:RDF xmlns="http://www.livewiredg.myby.co.uk/rdf/geo-layers/rail.owl#"

xmlns:cyc="http://www.cyc.com/2003/04/01/cyc#" >

<owl:Class rdf:about="&cyc;TransportationCompany"/>

<owl:Class rdf:ID="RailOperator">

<rdfs:subClassOf rdf:resource="#RailwayComponent"/>

<rdfs:subClassOf rdf:resource="&cyc;TransportationCompany"/>

</owl:Class> ……..

  • Is this acceptable? How would an agent understand the Cyc context of the superclass of “cyc:TransportationCompany”

Formalised specific class reuse
“Formalised” specific Class Reuse


  • Representation and reasoning with foreign ontologies (Grau et al, 2005)

  • Allows specific concept linking. Few tools available e.g. SWOOP (OWL Ontology Editor)



xmlns=http://www.owl-ontologies.com/flight.owl# ……..>

<owl:Class rdf:about=“&global;Artifact"/>

<owl:Class rdf:ID="Helicopter">




<owl:LinkProperty rdf:about="#hasForm"/>


<owl:someValuesFrom rdf:resource="&global;Artifact"/>




<owl:LinkProperty rdf:ID="hasForm">

<owl:foreignOntology rdf:resource="&global;"/>

<rdfs:domain rdf:resource="#Helicopter"/>


<owl:foreignClass rdf:about="&global;Artifact">

<owl:foreignOntology rdf:resource="&global; "/>




Formalised specific class reuse1
“Formalised” specific Class Reuse

  • SWOOP permits ontology partitioning (module extraction)

  • partitioning generates same syntax as “informal reuse” example

Class reuse by ontology import
Class reuse by Ontology Import


Map Rail Ontology class “RailOperator” to Cyc Ontology class “TransportationCompany”


Import Opencyc into Rail > 6.8MB


adds 2843 classes

1256 properties

6331 instances

Protégé “out of memory”

load time 1.5 to 7.5 mins

Alternative reuse approach
Alternative Reuse approach?

  • Consider the way Ontologies structured?

  • Break down domain ontologies into sub-components: effectively domain “sub-classes” (Layers / modules)

  • How to demonstrate?

  • Can be demonstrated using Geographical context

Why consider geography context
Why consider Geography Context?

  • Geographical concepts interact with virtually every aspect of daily life.

  • Geographical elements form a major part of information management systems.

  • Geographical ontologies offer a logical vehicle, to examine how Web semantics can be specified efficiently and effectively.

Pc and ontology analogy
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.

Ontological comparison
Ontological Comparison

  • Multiple sub-domains

    • potential redundancy

    • vulnerability to change

  • How relevant are they?

  • Ontology Reuse - Imports

    • should there be a similar approach?

    • E.g. if OTN 1 is imported: what do we see?

    • Ontology much smaller than Cyc, but …

  • Only for an application that uses ALL concepts

1OTN - Ontology of Transportation Networks (Lorenz et al, 2005)

Ontology permanence

Fixed Concepts

Variable Concepts

Ontology Permanence

Ontology permanence1

Fixed Classes

Variable Classes

Ontology Permanence

Transport ontology
Transport Ontology

  • 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 …..

Land transport


single-mode ?

Land Transport

Our transportation domain




Our Transportation Domain

Transportation domain layers




Transportation Domain Layers

Railway sub domain conceptualisation
Railway sub-domain Conceptualisation

Developing layers
Developing Layers

  • Need to “de-integrate” to allow low-cost integration

  • We are aiming towards “effectively” disjoint domains

  • Achieved by removing concept redundancy – potential duplication

  • Need to promote/relegate concepts and relations

  • Represents a separation of Form and Function both within and between ontology modules

  • e.g. see …… TransportInterchange, LevelCrossing

Rail transport ontology

Road domain

Rail Transport Ontology

Q: rename LevelCrossing → RoadCrossing?

But we don’t do roads in rail!

Road transport ontology

Rail domain

Road Transport Ontology

Q: rename LevelCrossing → RailCrossing?

But we don’t do rail in roads!

Road rail ontology multimodal

ChannelTunnel Terminal




Road-Rail Ontology: Multimodal

Benefits and issues
Benefits and Issues

  • 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