Re: "shape" as a relationship, not a class

On 2/9/2015 10:04, Karen Coyle wrote:
> Holger, even if it is a concept, and not a RWO, there still must be 
> only a single IRI for a single thing -- and for sure the subject is 
> not the same thing as the graph.

Sorry then we must have talked about different things. Surely, the IRI 
of a book should not represent the graph that the book is stored in. 
Could you rephrase what you were asking about (maybe with a concrete 
example)?

Thanks
Holger


>
> kc
>
> On 2/8/15 2:36 PM, Holger Knublauch wrote:
>> On 2/9/2015 4:36, Karen Coyle wrote:
>>> I'm trying to understand how the subject of a triple can be either of
>>> type shape or can have a shape.
>>>
>>> Let me make this more concrete. My subject is a book, which is a RWO,
>>
>> For a computer, your subject is not a RWO but a data structure
>> represented by triples. Humans may interpret this as a real-world book,
>> but this is IMHO largely philosophical.
>>
>>> and it has an IRI. I'm going to make various statements about this RWO
>>> (it has a title , it has an author, etc.). It makes little sense to me
>>> to say that this RWO "has a shape/graph." The graph has a shape, but
>>> using the same IRI to represent the RWO and the graph violates a basic
>>> rule that each IRI references one and only one "thing."
>>>
>>> It seems to me that the key difference between shapes and classes is
>>> exactly this: a shape is information about a graph; a class is
>>> information about the RWO. If the class of the RWO  is coincident with
>>> the graph that you wish to validate, then presumably the class can be
>>> used as a target for validation. However, that is making a use of the
>>> class which is not within the definition of class in RDF. I would find
>>> it inconsistent with RDF for us to encourage people to assign classes
>>> to RWO's that represent the graph itself.
>>
>> Could you point me at documents that proof that all classes in RDF must
>> be real-world objects? What about, for example, abstract data structures
>> such as rdf:Lists - rdf:List is also a class. Also please consider that
>> the term "class" is not exclusive to RDF Schema. It was already used by
>> object-oriented systems, for example. I am afraid the distinction
>> between real-world objects and their representation drifts into
>> theoretical realms that nobody outside of the RDF world seems to care
>> about (and rightfully so). I repeat my statement that there is zero
>> practical difference between the following options:
>>
>>      ex:Class
>>          a owl:Class ;
>>          rdfs:subClassOf [
>>              a owl:Restriction ;
>>              owl:onProperty ex:property ;
>>              owl:minCardinality 1 ;
>>          ] .
>>
>>      ex:Class
>>          a owl:Class ;
>>          ldom:property [
>>              a ldom:PropertyConstraint ;
>>              ldom:predicate ex:property ;
>>              ldom:minCount 1 ;
>>          ] .
>>
>> Holger
>>
>>
>>
>

Received on Monday, 9 February 2015 00:11:36 UTC