Re: Mapping to RDF Graphs and reification

On Dec 4, 2008, at 3:11 AM, Bijan Parsia wrote:

>
> On Dec 4, 2008, at 2:55 AM, Jeff Thompson wrote:
>
>> Thanks everyone for the comments.  Note that the message from Tim I  
>> quoted was
>> about provenance.
>> http://lists.w3.org/Archives/Public/semantic-web/2007Jan/0088.html
>> This issue is confusing because a first instinct for annotations is  
>> to use them
>> to give the provenance of a triple.
>
> In OWL, we focus on Axioms, but the point remains.
>
>>  Indeed the first annotation example in
>> the OWL 2 primer appears to be
>
> does address.
>
>> addressing this:
>>
>> Individual f:John
>>  Facts: Annotations: dc:author Individual(f:peter)
>>                      dc:creationDate "2008-01-10"^^xsd:date
>>                      rdfs:comment "A simple fact about John"
>>  f:hasWife f:Mary
>>
>> The confusion is that this is arguably NOT provenance data
>
> It definitely is provenance data.
>
>> about who is being quoted
>
> It is not a quotation. I definitely wouldn't conflate the two notions.
>
>> to say that f:John f:hasWife f:Mary, but rather an assertion that  
>> peter put
>
> I.e., the provenance of that axiom.
>
>> this
>> triple into THIS ontology according to the semantics that peter  
>> knew that
>> this ontology has for f:John, etc.  This is OK, and within the  
>> intended semantics
>> of OWL 2 annotations.
>>
>> If however there is someone else, such as Bob, out there in the  
>> world who is the
>> provenance source and is being quoted as saying that John hasWife  
>> Mary, then it
>> matters to quote how Bob said this.
>
> Annotations are not about quoting, for sure.
>
>>  If the ontology includes f:Mary sameAs f:SecretAgent99,
>> then Bob may never have said that John hasWife SecretAgent99, so it  
>> is not correct
>> to use an OWL 2 style annotation to *quote* what Bob originally  
>> said, because the
>> semantics of OWL 2 annotations absorb all the sameAs and other  
>> inferences in the ontology.
>
> I don't know what you mean by "absorb", but I suspect that it's not  
> quite as true as you'd like. Annotations do not follow entailments.
>
>> The problem is that many people will see OWL 2 annotations and leap  
>> on them to solve
>> the desperate need for provenance data in RDF/OWL, but they  
>> shouldn't.
>
> They solve a great deal of provenance issues people have (like  
> tracking who did what to which axiom) in building ontologies. They  
> do not, nor are they meant, to deal with quotation. However, they  
> can be used for things like tracking down whether it was two  
> separate people who added contradictory axioms, which of the  
> contradictory axioms came first, etc. You don't need (or want)  
> quotation for that.

Right. What you need is the ability to refer to the particular axiom  
(triple), and RDF reification does give you that. The re/dicto issue  
is all about the three URIs in the reified triple (in the reification,  
do they still refer to the same things?- yes in RDF) not about the  
triple itself.

Pat

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