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[p4-feedback] RE : Use of inverseFunctional for data properties

Timothy Redmond tredmond at stanford.edu
Wed Sep 22 07:46:44 PDT 2010


On 09/22/2010 01:21 AM, Evain, Jean-Pierre wrote:
> Hi Timothy,
>
> I appreciate the nature of the technical problem on punning and OWL versions.
>
> On the other hand, I have a non-technical issue, which is that W3C considers FOAF as the coolest possible way of describing persons and organisations (when I personally question the rdf and value of the geek profile that it really is .-).
>    

It is unfortunate that the foaf has this problem.  We will have to see 
how it goes.  The OWL api does the best that it can to parse any 
ontology.  The good thing is that this is an issue that permits a 
mapping to the functional owl syntax, even if it is prohibited.  Also 
maybe there will be a foaf-dl at some point if this becomes a serious 
problem.

> When you mention a problem with OWL API tools, you mean that most of them don't implement OWL FULL (yet, if ever?)
>    

I suspect that the only reasonable way to get complete support for OWL 
Full is to base your tool on RDF.  Not all constructs in OWL Full can be 
mapped to the structural specification of the language given in [1].

But this is not the only issue.  In this case another problem is the 
ambiguity of the mapping from RDF to OWL.  In particular, in my quick 
experiment yesterday to see how the OWL API dealt with an 
object/datatype property pun, after parsing the ontology the 
topDatatypeProperty was also punned as an object property.  I think that 
this happened somehow because in RDF the rdfs:subPropertyOf statement 
can be ambiguous without knowing the type of the resources.

I think that the OWL api and Protege 4 OWL will provide only limited 
support for OWL full.  Jena will probably provide this support as will 
other triple stores.  Also there is the seed of a plan to make a true 
Protege 4 RDF editor.  (Neither of the Protege 3 RDF editors are quite 
true to RDF specifications).

-Timothy

[1] http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/


> Regards,
>
> jean-pierre
>
> ________________________________
> De : p4-feedback-bounces at lists.stanford.edu [p4-feedback-bounces at lists.stanford.edu] de la part de Timothy Redmond [tredmond at stanford.edu]
> Date d'envoi : mercredi, 22. septembre 2010 10:03
> À : p4-feedback at lists.stanford.edu
> Objet : Re: [p4-feedback] Use of inverseFunctional for data properties
>
>
> Then could the described behaviour be a parsing problem?
>
> It is not clear that there is a good choice here.
>
> The foaf ontology seems to have a clear pun of an object property with a data property:
>
>
>    <rdf:Property rdf:about="http://xmlns.com/foaf/0.1/mbox_sha1sum"<http://xmlns.com/foaf/0.1/mbox_sha1sum>  vs:term_status="testing" rdfs:label="sha1sum of a personal mailbox URI name" rdfs:comment="The sha1sum of the URI of an Internet mailbox associated with exactly one owner, the  first owner of the mailbox.">
>      <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#InverseFunctionalProperty"<http://www.w3.org/2002/07/owl#InverseFunctionalProperty>/>
>          ... some discussion of inverse functional properties here ...
>      <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#DatatypeProperty"<http://www.w3.org/2002/07/owl#DatatypeProperty>/>
>
>
>
> Given this and the observation that
>
>
> Object and Data properties can not be punned.
> http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Typing_Constraints_of_OWL_2_DL
>
>
> it would seem that the obvious conclusion is that, strictly speaking, foaf is an OWL Full ontology that may give trouble to OWL API based tools.
>
> -Timothy
>
>
> On 09/22/2010 12:33 AM, Thomas Schneider wrote:
>
> On 22 Sep 2010, at 03:52, Alan Ruttenberg wrote:
>
> On Tue, Sep 21, 2010 at 4:04 AM, Thomas Schneider<schneidt at cs.man.ac.uk><mailto:schneidt at cs.man.ac.uk>  wrote:
>
> On 21 Sep 2010, at 08:43, Evain, Jean-Pierre wrote:
>
> Good morning.
>
> While looking at the FOAF ontology on Protégé 4.0, different properties,
> although declared as data properties, would be displayed as data and object
> properties.
>
> Would you confirm that this results from the fact that these properties
> are also declared as inverseFunctional, which would seem to make them look
> like object properties to Protégé?
>
> I don't know the FOAF ontology, but I suspect that the described behaviour
> is due to punning, which is allowed in OWL 2: two entities of different type
> (e.g. an object property and a data property) can have the same name.
>
> Object and Data properties can not be punned.
> http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Typing_Constraints_of_OWL_2_DL
>
> Hmmm, sorry for overlooking this ...
>
> Then could the described behaviour be a parsing problem? It might be worth trying to open the same ontology with the recent Protégé version (4.1 beta), where conformance with the OWL specification has been improved.
>
> But maybe someone from the Protégé team should comment on this.
>
> Cheers
>
> Thomas
>
>
> It is
> possible that, if the parser reads an InverseFunctional statement, that the
> property is punned and treated as an object property for this particular
> statement and as a data property otherwise.
>
> However, I can't say for sure that this is the actual reason.
>
> It also seems, still on Protégé 4.0 that it is not proposed to declare
> data properties as being inverseFunctional. Any reason?
>
> Neither in 4.0 nor in 4.1 can you declare data properties as inverse
> functional. The reason is that the OWL specification doesn't allow this. If
> it were allowed, reasoning would become an undecidable problem.
>
> Interesting to note that reasoners accept all this.
>
> I'm not sure what exactly you mean. If you invoked the reasoner within
> Protégé, it worked on the representation of the ontology created by Protégé
> (or the underlying OWL API). Since the properties in question had been
> punned during parsing as described above, the reasoner got the
> InverseFunctional statements for object properties. However, if you invoked
> a reasoner directly, e.g., Pellet on the command line, then they might
> simply have used punning too.
>
> Cheers
>
> Thomas
>
>
> What do you think?
>
> Regards,
>
> Jean-pierre
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> |  Dr Thomas Schneider                    schneider (at) cs.man.ac.uk  |
> |  School of Computer Science       http://www.cs.man.ac.uk/~schneidt  |
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> |  University of Manchester                                            |
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> +----------------------------------------------------------------------+
> |  Dr Thomas Schneider                    schneider (at) cs.man.ac.uk  |
> |  School of Computer Science       http://www.cs.man.ac.uk/~schneidt  |
> |  Kilburn Building, Room 2.114                 phone +44 161 2756136  |
> |  University of Manchester                                            |
> |  Oxford Road                                             _///_       |
> |  Manchester M13 9PL                                      (o~o)       |
> +-----------------------------------------------------oOOO--(_)--OOOo--+
>
> Fremantle (vb.)
>    To steal things not worth the bother of stealing. One steals cars,
>    money and silver. Book matches, airline eyepatches and individual
>    pots of Trust House Forte apricot jam are merely fremantled.
>
>                    Douglas Adams, John Lloyd: The Deeper Meaning of Liff
>
>
>
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