[Pellet-users] Inferred Subsumption

[Evren Sirin]

On 3/4/08 5:09 PM, JPQ wrote:
> Thanks for your reply.
>
> Let me phrase it a bit differently.
>
> First, we have the following OWL class, which is contained within an OWL-DL
> ontology. In fact this ontology only contains this one class and no
> properties. Additionally, it imports a second ontology, which I have called
> "Another_Ontology".
>
> <owl:Class rdf:ID="LatLon">
>    <owl:unionOf rdf:parseType="Collection">
>       <rdf:Description rdf:about="Another_Ontology.owl#Lat"/>
>       <rdf:Description rdf:about="Another_Ontology.owl#Lon"/>
>    </owl:unionOf>
> </owl:Class>
> The named OWL class, "LatLon", is equivalent to the nested anonymous class
> that is formed by the "unionOf" set operator. For example, suppose the class
> extension of "Lat" is represent by the set {1, 2, 3}, and the class
> extension of "Lon" is represented by the set {4, 5, 6}. Then the class
> extension of "LatLon" is exactly the same as the union of those two sets -
> namely, {1,, 2, 3, 4, 5, 6}.
>
> Yet, when run through Pellet, it is inferred that "Another_Ontology.owl#Lat"
> & "Another_Ontology.owl#Lon" are subclasses of "LatLon".
>
> My question is what is the basis of these inferences?
>   

This inference follows from the definition of owl:unionOf. If a class is 
the union of other classes those classes are necessarily subclasses of 
the union class. Your example above shows this, too. All the instances 
of classes Lat and Lon should be instances of LatLon class meaning both 
those classes are subclasses of LatLon.

Cheers,
Evren
> Thanks.
>
> On 3/4/08, Evren Sirin <evren at clarkparsia.com> wrote:
>   
>> On 3/4/08 11:51 AM, JPQ wrote:
>>     
>>> I'm running the Pellet inferencing engine in TopBraid Composer on a
>>>       
>> valid
>>     
>>> OWL-DL document. Here are the details.
>>>
>>> An OWL-DL ontology contains the following class.
>>> <owl:Class rdf:ID="LatLon">
>>>    <owl:unionOf rdf:parseType="Collection">
>>>       <rdf:Description rdf:about="Another_Ontology.owl#Lat"/>
>>>       <rdf:Description rdf:about="Another_Ontology.owl#Lon"/>
>>>    </owl:unionOf>
>>> </owl:Class>
>>>
>>> The anonymous class formed by the "unionOf" set operation is equivalent
>>>       
>> to
>>     
>>> the named class, "LatLon".
>>>
>>> This ontology imports a second ontology.
>>>
>>> The second OWL-DL ontology ("Another_Ontology") has the following
>>>       
>> features:
>>     
>>> 1. The "Lat" & "Lon" classes are Type-1 OWL classes (ie, they are simply
>>> identified as RDF nodes using the rdf:ID construct)
>>> 2. There exist "lat" & "lon" datatype properties
>>>     a. The "lat" property domain is "Lat"; its range is "xsd:double".
>>>       
>> The
>>     
>>> same applies with "lon",
>>>         except its domain is "Lon".
>>>         (I've also tried an alternate version where the "lat" & "lon"
>>> datatype properties only define
>>>         ranges and not domains.)
>>>
>>>     b. Both the "lat" & "lon" datatype properties are also typed with
>>> <owl:FunctionalProperty>
>>>
>>>  Running the Pellet inference engine on the first ontology results in
>>>       
>> the
>>     
>>> following inferences.
>>>       Another_Ontology:Lat rdfs:subClassOf LatLon
>>>       Another_Ontology:Lon rdfs:subClassOf LatLon
>>>
>>> The "LatLon" class subsumes "Lat" & "Lon".
>>>
>>>       
>> Ok, everything sounds right until now.
>>
>>     
>>> Why does Pellet infer these subsumptions when the "LatLon" class
>>>       
>> description
>>     
>>> defines an equivalency?
>>>
>>>       
>> I don't understand the question or the problem. Are you saying that the
>> subclass relations do not hold when you change the definition of LatLon?
>> If so, what is the changed definition? Providing complete, minimal
>> ontologies would help us understand what is wron.
>>
>> Cheers,
>> Evren
>>     
>>> Thanks for your help.
>>>
>>>
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>>>       
>>     
>
>