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

RDF specification clearly says that there are 3 types of RDF nodes: IRI, blank node and literal. Each has its own unique/different characteristics including, for example, that literal can only be an object of a triple and blank node can't be a predicate of a triple.

I believe the specification makes it clear that these  three node types are disjoint. Thus, ex:two can not be a literal node as it is an IRI. I also thought we were discussing here RDF nodes, not abstract concepts of literals.

I remember hearing that there were some discussions in the RDF working group about letting literals be subjects, but this proposal was rejected, wasn't it?

Irene

Sent from my iPhone

> On Dec 22, 2014, at 8:49 AM, "Peter F. Patel-Schneider" <pfpschneider@gmail.com> wrote:
> 
> 
> 
>> On 12/22/2014 01:45 AM, ☮ elf Pavlik ☮ wrote:
>>> On 12/21/2014 01:38 AM, Peter F. Patel-Schneider wrote:
>>> In RDF all resources can have property values, even literal values.
>>> 
>>> peter
>> Hi Peter :)
>> 
>> Could you please explain it little more and if possible share links to
>> relevant references?
>> 
>> Thanks!
> 
> The original version of RDF, as described in the RDF Model and Syntax Specification http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/, talks about Resources and Literals, but does not indicate directly whether they are disjoint.  However, there is already the idea that anything is a resource and that anything can described by a URI.  See Section 2
> http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#basic and Section 5 http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/#model for more information.
> 
> The original version of RDFS, http://www.w3.org/TR/1998/WD-rdf-schema/, which never became a full W3C recommendation, has the initial class hierarchy, including rdfs:Resource, rdfs:Literal, rdfs:Class, and rdf:Property in Figure 2.   In this figure, rdfs:Resource is the universal class, with rdfs:Class, rdf:Property, and rdfs:Literal all as subclasses.  Here is the first direct requirement that literal values are resources.
> 
> The first formal treatment of RDF is in RDF Semantics http://www.w3.org/TR/2004/REC-rdf-mt-20040210/.  Here interpretations for RDF are first defined, in Section 1.3 http://www.w3.org/TR/2004/REC-rdf-mt-20040210/#interp, with the domain of an interpretation being the set of resources and a subset of the resources being literal values, as in the original version of RDFS.  Properties are another subset of the resources, which are linked to their extent, which is a set of pairs over the resources.  There is no requirement here that literals cannot be the first element of a property pair.
> 
> 
> One might argue that the formal treatment is a misreading of the informal 1999 description of RDF, but the ability for literals to have property values has definitely been in RDF since at least 2004.  This stance is also consistent with the dictum that URIs can identify anything, which includes literal values.
> 
> For example, one can say in RDF
> 
> ex:two rdf:type xsd:Integer .
> ex:two ex:prime xsd:true .
> 
> 
> Peter F. Patel-Schneider
> Nuance Communications
>

Received on Monday, 22 December 2014 14:40:16 UTC