Re: Terminology: How to call "IRI or blank node"?

As we are here defining requirements that meet actual needs, don't we 
now have a requirement to include in the shapes or validation solution 
the ability to define an object type that excludes literal values? 
(Assuming others also find this requirement compelling.) Later we can 
determine whether/how that can be done. If it cannot be done with RDF, 
then I would hope that actual user needs are taken into account in RDF 
development, which I assume is not frozen at this point in time. If it 
cannot be done with RDF now or ever, then we are back to "The Model's 
Broken!" which is already one of our stories.

kc

On 12/20/14 7:12 AM, Peter F. Patel-Schneider wrote:
>
>
> On 12/19/2014 11:36 PM, Holger Knublauch wrote:
>>
>> On 12/20/14, 4:33 PM, Eric Prud'hommeaux wrote:
>>>
>>> > We need a URI for that, so that we can say that "every value of a
>>> given
>>> property must be a resource". Basically a way to say "anything that can
>>> appear as a subject in a triple (and therefore can have its own
>>> properties).
>>> We have always used rdfs:Resource for that and it worked well in
>>> practice -
>>> and rdfs:Literal to say "every datatype". rdfs:NonLiteral does not
>>> exist.
>>> OWL had owl:ObjectProperty and owl:DatatypeProperty, and if you left
>>> their
>>> range empty then they had that default interpretation. How was this ever
>>> supposed to work in RDF Schema?
>>>
>>> RDFS never needed to address this distinction (arguably because it's
>>> not s
>>> schema language). It is certainly better to mint a new term than to
>>> confuse
>>> the meaning of an existing term.
>>>
>>
>> I would be OK with a different term but this should then become the
>> superclass
>> of all other classes, so that the inheritance model is consistent.
>> Currently
>> only rdfs:Resource can play this role I think, but that unfortunately
>> includes
>> literals. And owl:Thing would suck in way too much complexity just for
>> this
>> technical detail (and existing models that use rdfs:subClassOf
>> rdfs:Resource
>> would be excluded too).
>>
>> Holger
>>
>>
>
> It appears that you are asking for the class whose instances are all
> resources excluding literal values.  The expressive power required for
> this class goes well beyond the bounds of RDFS.
>
> This new class cannot be the superclass of all classes.  It is not a
> superclass of the class that is the fixed meaning of rdfs:Resource, of
> course, and it is also not a superclass of class that is the fixed
> meaning of rdfs:Literal or of any of the datatype classes.  Making this
> class a superclass of all classes would break RDFS.
>
> It would also not be the case that the meaning of all IRIs and blank
> nodes would belong to this new classes.  In RDF the meaning of an IRI or
> a blank node can be a literal value.
>
>
> peter
>
>

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

Received on Saturday, 20 December 2014 15:51:44 UTC