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

Yes, we may be talking past each other, but most likely I'm not 
correctly reading your examples since I don't speak SPARQL/SPIN code and 
have no idea what a "magic property" is. (Examples illustrated with 
instance data could help.)

In the glossary "shape" is defined as "a set of constraints over RDF 
graphs".

So, with this simple example (and note that there are no classes, either 
explicit or implicit):

http://lccn.loc.gov/75300479
    dct:title "Moby Dick" ;
    dct:creator <http://id.loc.gov/authorities/names/n79006936> ;
    dct:publisher "M. Kennerley" .

Were you suggesting to add the relationship "hasShape" to this graph 
like this:

http://lccn.loc.gov/75300479
    ldom:hasShape ex:bookShape ;
    dct:title "Moby Dick" ;
    dct:creator <http://id.loc.gov/authorities/names/n79006936> ;
    dct:publisher "M. Kennerley" .

If so, this still looks to me to be saying that my book has a 
relationship to a set of constraints.

kc


On 2/8/15 4:10 PM, Holger Knublauch wrote:
> 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
>>>
>>>
>>>
>>
>
>
>

-- 
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 01:23:19 UTC