Re: shapes and classes: different

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On 02/05/2015 08:19 AM, Richard Cyganiak wrote:
> Hi Peter,
> 
>> On 5 Feb 2015, at 10:38, Peter F. Patel-Schneider
>> <pfpschneider@gmail.com> wrote:
>> 
>> How does one include anything in a class definition in RDF or RDFS?
> 
> Well, one could write it in prose text into the specification that
> defines the class.

Yes, but how does this get used in tools?

> One could also write it into an rdfs:comment or skos:definition in the
> RDFS file that defines the class.

Again, how does this get used in tools?  Also, how is an RDFS file made the
definition of a class?

> Or, if one has appropriate vocabulary, one could say it directly in
> triples in that RDFS file.

OK, so long as the RDFS file can be identified, and one has the appropriate
vocabulary.

>> What is a class definition in RDF or RDFS?
> 
> 
> I’ll answer by giving an example. Here’s the definition of the class
> qb:Dataset:
> 
> http://www.w3.org/TR/void/#dataset
> 
> A pitifully small part of that definition is also written down in the
> associated RDFS file here:
> 
> [[[ void:Dataset a rdfs:Class, owl:Class; rdfs:label "dataset"; 
> rdfs:comment "A set of RDF triples that are published, maintained or
> aggregated by a single provider." . ]]]

So some triples in some RDFS file that have the class as a subject are in
the definition.  But which triples?

>> What does it mean to include a shape in a class definition?
> 
> Here’s what I mean when I use these words:
> 
> 1. The shape is published in the RDFS file that defines the class
> (assuming shapes can be expressed in triples).

Again, this depends on being able to determine which RDFS file defines the
class.

> 2. If an RDF graph G includes a statement that claims a resource X to be
> a member of the class, but the description of X in G doesn’t fit the
> shape, then G is “invalid”, for some to-be-defined notion of “validity”.
> The important thing is that a validator can detect the condition.
[I'm assuming that you mean "includes a triple X rdf:type C" or something
like that.]

So to determine validity one has to find the RDFS file that defines the
class.  How is this done?

> 3. Maybe it also means that G is “shape-inconsistent”.
> 
> Best, Richard

peter

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Received on Thursday, 5 February 2015 17:03:53 UTC