RE: Proposal to resolve ISSUE-86

Hi Alan and Mike!

I think the core of the problem is the RDF mapping of PropertyAssertionS: A functional syntax expression of the form

  ObjectPropertyAssertion(p s o)

is mapped to the RDF triple

  s p o

And if p is anonymous, then there will simply exist no mapping. 

InversePropertyExpressionS only bring this problem to our attention, they are not the problem themselves. If there were any other way to create anonymous properties, then this problem would arise again in principle. So IMO it is the wrong way to think about the interplay between object property assertions and inverse property expressions. In order to solve the problem, only the RDF mapping for property assertions should be considered, independent on inverse property expressions.

My preferred solution would also be to only allow named properties in property assertion axioms, but for a different reason: There would then be an exact correspondence between syntactically valid property assertion expressions in functional syntax, and syntacticaly valid triples in RDF.

But I recognize that there are people who dislike this restrictive suggestion. So an alternative might be for them to have a conditional RDF mapping:

  ObjectPropertyAssertion(p s o) --->

    IF "p" is a name 
        s p o
    ELSE
        s rdf:type owl11:ObjectRestriction 
        s owl:onProperty _:p 
        s owl:hasValue o

And analogue for DataPropertyAssertionS.

Not nice at all, I admit, but the RDF weakness (no bNodes in predicate position) has to be circumvented somehow. And it seems to me that this would at least be a technical solution. 

Of course, if the mapping would instead only allow named properties, the author of an ontology would still be free to do such a complex encoding of a property assertion himself manually.

Cheers,
Michael

>-----Original Message-----
>From: public-owl-wg-request@w3.org 
>[mailto:public-owl-wg-request@w3.org] On Behalf Of Michael Smith
>Sent: Wednesday, March 26, 2008 2:46 PM
>To: Alan Ruttenberg
>Cc: public-owl-wg@w3.org
>Subject: Re: Proposal to resolve ISSUE-86
>
>
>On Sun, 2008-03-16 at 21:30 -0400, Alan Ruttenberg wrote:
>> RDF/XML serialization for anonymous inverse properties
>
>> I think it is beneficial to allow for anonymous inverses in  
>> ObjectPropertyAssertion.
>
>Can you elaborate this?  If we don't have a real requirement for this,
>the simplest resolution* to ISSUE-86 is to require named object
>properties in object property assertions.
>
>I.e., change
>
>objectPropertyAssertion := 'ObjectPropertyAssertion' '(' { 
>annotation } objectPropertyExpression sourceIndividualURI 
>targetIndividualURI ')'
>
>to
>
>objectPropertyAssertion := 'ObjectPropertyAssertion' '(' { 
>annotation } objectPropertyURI sourceIndividualURI 
>targetIndividualURI ')'
>
>Regards,
>-- 
>Mike Smith
>
>Clark & Parsia
>
>* Thanks to Evren for reporting this issue and suggesting this simple
>resolution to me.
>
>
>

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
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Email: Michael.Schneider@fzi.de
Web  : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555

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