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[p4-feedback] Reasonableness of Ontology

Igor Toujilov i.toujilov at
Thu Apr 22 07:10:13 PDT 2010

A good practice of modelling in OWL is first to make it clear what should
be inferred by a reasoner, and then to construct an OWL model that allows
such reasoning. So, if you specify exactly what you want to be inferred,
including examples (test cases), creating a suitable OWL model will be

And another note on modelling optional occurrences in OWL: you do not need
to specify an optionality in your model because any optionality is assumed
by the default, according to the principle of the open world. Any empty
ontology in OWL is already a model of the universe with all possibilities.


> Hello,
> as this is one of the most active user lists on the net i try to post my
> question here and hope someone can answer it. it is a fundamental
> question:
> i am trying to map some XML-Schema to an OWL document and have the
> following issue.. lets take a look at one of the elements in the
> XML-Schema:
> 	<xsd:element name="Dimensions">
> 		<xsd:complexType>
> 			<xsd:choice minOccurs="0" maxOccurs="unbounded">
> 				<xsd:element ref="Height" minOccurs="0"/>
> 				<xsd:element ref="Width" minOccurs="0"/>
> 				<xsd:element ref="Length" minOccurs="0"/>
> 			</xsd:choice>
> 		</xsd:complexType>
> 	</xsd:element>
> so this means in the element Dimensions there can be one or more optional
> elements of type Height,Width and Length.
> This element goes to the following element in OWL (Manchester Syntax
> converter is down, so i have to post the full owl code, sorry):
>    <owl:Class rdf:about="#Dimensions">
>       <rdfs:subClassOf>
>          <owl:Class>
>             <owl:unionOf rdf:parseType="Collection">
>                <owl:Restriction>
>                   <owl:onProperty rdf:resource="#containsHeight"/>
>                   <owl:someValuesFrom rdf:resource="#Height"/>
>                </owl:Restriction>
>                <owl:Restriction>
>                   <owl:onProperty rdf:resource="#containsWidth"/>
>                   <owl:someValuesFrom rdf:resource="#Width"/>
>                </owl:Restriction>
>                <owl:Restriction>
>                   <owl:onProperty rdf:resource="#containsLength"/>
>                   <owl:someValuesFrom rdf:resource="#Length"/>
>                </owl:Restriction>
>             </owl:unionOf>
>          </owl:Class>
>       </rdfs:subClassOf>
>    </owl:Class>
> does this make sense? can the reasoner infer something out of this class?
> especially the "unionOf" connection between the superclasses? in my
> opinion it is not possible to make an "intersectionOf" because the XML
> element does allow optional occurrence of the element. is there another
> possibility to model optional occurrence in owl?
> i am thankful for any tip and explanations on this topic.
> best regards,
> mario
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Dr Igor Toujilov
Senior Research Fellow
Centre for Health Informatics and Multiprofessional Education
University College London
Highgate Hill
London, UK
N19 5LW

Tel: +44 (0)20 7288 3960

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