Re: To embed or combine

Jos de Bruijn wrote:
> 
> Dave Reynolds wrote:
>> Jos de Bruijn wrote:
>>> Dave,
>>>
>>> I'm afraid I don't really see the difference between "accessing RDF
>>> data" and "entailment regimes", so I don't really understand why they
>>> should be treated differently.
>> I'm not suggesting they be treated differently.
>>
>> To write rules that work with the data, or to implement a translator for
>> those rules, the data mapping does have to normatively defined. To me
>> this means that tr and the treatment of bNodes in data (not necessarily
>> queries), literals etc have to all be normative. In the current document
>> almost all of that is covered - literals are in the normative part, tr
>> is implicit in the model theory but the handling of bNodes is not
>> spelled out. Spelling tr out and defining the bNode handling in the
>> normative part would resolve this, and would further increase the
>> clarity of the document, at the trivial cost of moving a very small
>> number of lines of text around.
> 
> I'm not sure what you mean with "spelling out tr". If you mean that we
> need to show how using RDF data with RIF rules can be done, then it is
> indeed something we still need to do, in the "Guide to using RIF with
> the semantic web" document you mentioned.

We want that too but simply defining tr in the normative part is also 
simple and useful.

> The handling of bNodes is indeed not spelled out, because it is implicit
> in the semantics.  They are symbols local to an RDF graph, so a
> combination does not need to, and should not, touch these symbols.  We
> do, however, need more explanatory text about this point.

No, we need to define the mapping so that builtins like isBlankLiteral 
are implementable. It makes a difference whether they are represented by 
undistinguisable URIs (your proposal) or by distinguisable URIs or by a 
datatype (my proposal).

> So, with respect to the handling of blank nodes I think we are fine in
> the normative part; we simply need more explanation in the informative part.


>>> Wouldn't one simply use a combination with the simple entailment regime
>>> in this case?
>> Yes, I pointed this out in the "at first I was concerned" paragraph
>> (since subset semantics includes the trivial subset).
> 
> I did not understand what is meant with "subset semantics".  Also, could
> you send a pointer for rho-df?

It's the ESWC-07 best paper that you yourself referenced. They called 
their reduced RDFS {\rho}df did they not?

Dave
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Received on Tuesday, 11 September 2007 08:45:12 UTC