Re: New Proposal (6.1) for GRAPHS

On Apr 2, 2012, at 22:22 , Pat Hayes wrote:

> (Sorry about delay in responding) 
> 
> On Mar 30, 2012, at 3:41 AM, Ivan Herman wrote:
> 
>> Pat,
>> 
>> just wondering...
>> 
>> On Mar 29, 2012, at 17:47 , Pat Hayes wrote:
>> 
>>> 
>>> Contrary to what I said in the telecon yesterday, I now don't think there is any way out of this within the current RDF framework. Basically, you want to talk about the naming relation between a URI and a denotation, and you can't do that in a conventional  rdf-2004-style model theory. You need a small amount of referential opacity to make this work. We will have to change something to get that.
>>> 
>> 
>> My disagreement[1] with Sandro on his approach has been on his usage of the rdf:hasGraph relationship and his approach of describing things through these terms. Ie, to try to explain things in terms of the RDF semantics.
> 
> I dont really follow your reasoning about this being "in terms of the RDF semantics", but whatever.
> 
>> 
>> My approach was much looser; we do define RDF classes for the various relationships (say, rdf:GraphLabel and rdf:Graph) but only as some sort of categorization for applications that require that, but the exact, hm, behaviour (I did not want to use the word 'semantics') of what
>> 
>> <a> { a b c }
>> 
>> means in term of loose labeling, equality, or strict HTTP retrieval, would be left to English prose, _not_ part of the RDF semantics per se. Is this what you mean?
> 
> No, I was just noting a technical flaw in Sandro's machinery. I am sure it could be fixed, but to do so does require some tweaking of the 2004 model theory (or at least extending it to quads in a particular way)
> 
>> Would that be a way out at least for the coming years?
> 
> Well, it IS a way out, yes. I have already suggested (and I was being serious) that we officially abandon (or make "informative") any formal model theory for RDF, and say explicitly that it can be used in any way one wants, which takes the same viewpoint even further. But I guess that my position would be that we either do one or the other. If RDF has a normative model theory, then it should all have it. And if part of it doesn't have one, then there really isn't much point in the rest of it having one, IMO. 

Well (obviously) I would not go that far. But there may be part of the RDF behaviour that cannot completely described with the current Semantics. For example, although I know that Sandro used that as an optional feature, if we want to be able to say

<a> { p q r . }
<a> rdf:type rdf:GetSemanticsGraph .

and what we mean by that is that 'if we issue an HTTP GET on <a> we would get back an RDF Graph in some standard serialization, and that graph would consist of (p q r)', well, I guess we could describe the whole semantics through some formal means that would involve providing a formalism for HTTP but, well, I do not think we would/should go there. Ie, in this case, the fact of <u> belonging to a particular class has some consequences that are described in English prose. That would not invalidate RDF 2004 at all, just having a clear idea of its boundaries.

I believe that the current approach of Sandro could be handled this way; that would provide with interoperable RDF environments which, after all, is what we want, and we can hope to do that within a foreseeable time.

Ivan

> 
> Pat
> 
>> 
>> Ivan
>> 
>> 
>> [1] http://lists.w3.org/Archives/Public/public-rdf-wg/2012Mar/0126.html
>> 
>>> Pat
>>> 
>>> 
>>> 
>>>> 
>>>> That page includes answers to all the current GRAPHS issues, including
>>>> ISSUE-5, ISSUE-14, etc.
>>>> 
>>>> Eric has started going through Why Graphs and adding the examples as
>>>> addressed by Proposal 6.1:
>>>> http://www.w3.org/2011/rdf-wg/wiki/Why_Graphs_6.1
>>>> 
>>>>  -- Sandro (with Eric nearby)
>>>> 
>>>> 
>>>> 
>>> 
>>> ------------------------------------------------------------
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>>> 
>>> 
>>> 
>>> 
>>> 
>> 
>> 
>> ----
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>> 
>> 
>> 
>> 
>> 
> 
> ------------------------------------------------------------
> IHMC                                     (850)434 8903 or (650)494 3973   
> 40 South Alcaniz St.           (850)202 4416   office
> Pensacola                            (850)202 4440   fax
> FL 32502                              (850)291 0667   mobile
> phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
> 
> 
> 
> 
> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
FOAF: http://www.ivan-herman.net/foaf.rdf