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

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.

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
>
>
>

-- 
Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600

Received on Monday, 9 February 2015 00:04:43 UTC