W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > June 2001

Re: draft partitioning of the issues

From: Aaron Swartz <me@aaronsw.com>
Date: Tue, 26 Jun 2001 11:28:27 -0500
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: rdf core <w3c-rdfcore-wg@w3.org>
Message-Id: <20010627014303.JVIT26850.femail19.sdc1.sfba.home.com@localhost>
On Tuesday, June 26, 2001, at 08:33  AM, Brian McBride wrote:

>>> Is there any doubt that as far as m&s is concerned:
>>>
>>>   o literals are not allowed as subjects
>>>   o literals are not resources
>> I do not see either of these stated in the spec.
> Yes, I think you are right that it does not state explicitly that they
> are disjoint.  In reading the spec I ascribe some information to the
> fact that m&s calls out that an object can be either a resource or a
> literal and says only that subject is a member of resources.  
> Whilst this
> may not be a mathematically precise statement that resources and
> literals are disjoint, it seems pretty clear that it was the intent
> that they are and that subjects may not therefore be literals.

Really? I've always interpreted this to mean that Literals are a 
subset of resources -- I'm not the only one, TimBL seems to have 
too:

<q cite="http://www.w3.org/2000/10/swap/cwm.py">
class Literal(Thing):
     """ A Literal is a data resource to make it clean

     really, data:application/n3;%22hello%22 == "hello" but who
     wants to store it that way?  Maybe we do... at least in 
theory and maybe
     practice but, for now, we keep them in separate subclases of Thing.
     """
</q>

Looking at the code he also seems to store them this way, 
although it's not exactly clear.

> I would agree with you that this could be made more clear.  But I'm
> not sure this is what you are suggesting.

No, I'm suggesting that we make Literals a subset of Resources.

>>> Which is maybe not how some folks would like it to be.  If we
>>> considered introducing this change, do you think we would need 
>>> a syntax change to represent it?  Of course, anyone can now 
>>> use data uri's now if
>>> they want to. We don't have to do anything to support that.
>> No, I do not think a syntax change is necessary. This is simply
>> a change to the abstract syntax.
> Could you give an example of using the current RDF/XML syntax to
> represent a literal as a subject.

Well, it depends on how we define the abstract syntax. I'd 
suggest something like:

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
xmlns="http://rdf.example.org/#">
<rdf:Description rdf:about="data:text/plain;Chicago">
   <startsWith>C</startsWith>
</rdf:Description>
</rdf:RDF>

become:

<data:text/plain;Chicago> <http://rdf.example.org/#startsWith> 
<data:text/plain;C> .

The XML syntax need not change for this.
--
       "Aaron Swartz"      | ...schoolyard subversion...
  <mailto:me@aaronsw.com>  |  <http://aaronsw.com/school/>
<http://www.aaronsw.com/> | because school makes kids dumb
Received on Tuesday, 26 June 2001 21:43:06 EDT

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