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

 URIs can be used to identify and describe any *thing* - the distinction of
RWO is not important. Shapes are things that can and should be
representable using RDF.

m.

Michel Dumontier, PhD
Associate Professor of Medicine (Biomedical Informatics)
Stanford University
http://dumontierlab.com

On Fri, Feb 20, 2015 at 3:04 PM, Holger Knublauch <holger@topquadrant.com>
wrote:

>
> On 2/21/15 1:15 AM, Arthur Ryman wrote:
>
>> Holger Knublauch <holger@topquadrant.com> wrote on 02/08/2015 05:36:32
>> PM:
>>
>>  ... 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).
>>>
>>
> My above statement was in response to a previous statement in the thread
> that
>
> > 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.
>
> To highlight why this distinction is problematic, look no further than
> SHACL itself.
>
>     sh:Shape rdf:type rdfs:Class .
>
>     ex:MyShape rdf:type sh:Shape .
>
> Shapes are not RWOs. There are similar examples everywhere.
>
> Should it instead be
>
>     ex:MyShape sh:nodeShape sh:Shape ?
>
> Then, what would sh:Shape be?
>
>     sh:Shape sh:nodeShape sh:Shape ?
>
> Welcome to a parallel semantic web that may become an even smaller niche
> than the current semantic web, and meanwhile confuses newcomers to the
> class-based semantic web even more.
>
> Regards,
> Holger
>
>
>
>  Holger,
>>
>> The distinction is important in some cases because if you fail to make the
>> distinction, then when you read the RDF, it sounds like nonsense. The
>> classic example is the distinction between a person and a user account
>> owned by that person. A person is a RWO and should have a URI that is
>> different that the user account, which is an information resource (a web
>> document).
>>
>> A web document can have properties such as creator (a person), creation
>> date, modification date, etc. It makes sense to say that a user account
>> document has a modification date, but it is nonsense to say that the
>> person who owns the user account has that modification date (barring
>> coincidental plastic surgery on that date). FOAF makes this clear. This
>> whole topic is nicely discussed in [1], which is co-authored by your
>> newest colleague.
>>
>> [1] http://www.w3.org/TR/cooluris/
>>
>>
>>
>
>