W3C home > Mailing lists > Public > public-rdf-wg@w3.org > December 2011

Re: [GRAPH] graph deadlock?

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 20 Dec 2011 12:54:08 -0600
Cc: public-rdf-wg@w3.org
Message-Id: <1E4FF14D-10C7-4573-8979-76DA28AA9E5F@ihmc.us>
To: Antoine Zimmermann <antoine.zimmermann@emse.fr>

On Dec 20, 2011, at 4:17 AM, Antoine Zimmermann wrote:

> 
> 
> Le 19/12/2011 21:28, Richard Cyganiak a écrit :
>> Pat,
>> 
>> On 17 Dec 2011, at 17:21, Pat Hayes wrote:
>>>> (1) RDF Datasets. It consists of labelled graphs: (G, l), where l
>>>> is an URI. (Some raised the possibility to use literals for 'l',
>>>> but I think there is a consensus to use URI-s). There is no
>>>> semantic relationship between 'G' and 'l', so something like
>>>> (with an ad-hoc syntax here):
>>>> 
>>>> ( {a:b c:d e:f}, mailto:ivan@w3.org }
>>>> 
>>>> is a perfectly o.k. labelled graph in an RDF Dataset
>>> 
>>> Fine so far, but we get into a problem when we do the details. I
>>> personally have no problem (well, a kind of private horror, but
>>> thats just me) with datasets as you describe them here. The problem
>>> is, people apparently want to both have these AND use the URIs in
>>> them to refer to the associated graph in RDF triples (eg in
>>> 'metadata' graphs.) And that combination is simply illegal,
>>> according to the 2004 RDF specs.
>> 
>> You keep saying things like that.
>> 
>> I keep asking for quotations from the specs that back up these
>> claims.
>> 
>> You never deliver, or deliver only a vague pseudo-arguments that rely
>> on unstated assumptions not required by the specifications.
>> 
>> When you say “this is illegal in RDF” then I think this has to be
>> read as “I don't like it”.
> 
> In this particular, it's trivial that it does not work. You can't have something that RDF-denotes a graph and RDF-denotes something else at the same time.
> 
> But this is probably irrelevant as a URI does not need to "denote" it can simply be "associated with". E.g., ex:me associated with a graph *and* denotes me. It's clear that this is causing trouble to people who would like the URI to denote the graph, but we have to live with it as, apparently, it is common practice.

Just to clarify: I am not objecting to the "associated with but not denotes" idea in itself. LIke I say, it gives me a headache, but that is just me. But what I do object to is when this URI is USED IN RDF TRIPLES with the intention and purpose of DENOTING the graph it is associated with. If we say that the URI does not denote the graph, then we cannot turn around and immediately use it denote the graph in RDF. Or at any rate, to justify this usage, we need to either simply accept that it violates the RDF specs, and say why, or else modify those specs to make it legal. And this second can I think be done, but it will be complicated and many readers will find it obscure and wonder why we bothered. 

What I do not find acceptable is for us to just say, it doesn't matter, do whatever the hell you like and as long as it works (for you), it meets the standard. IF this is to be the WG's position, then we might as well pack up and go home, as the whole standard will be irrelevant. Which might indeed, I am rapidly coming to the conclusion, be the best thing to do. It would certainly give us all more time to do more interesting and useful things than arguing about the nature of meaning. Philosophy is pretty boring even when it is done by philosophers, but when it is done by enthusiastic programmers it becomes intolerable.

Pat


> 
>>> We could simply declare that RDF has no semantics, and is simply to
>>> be used by programmers to mess around with in ways they find handy.
>>> Really, this might be the best way to move forward. But until we do
>>> this, we have to take the semantics seriously.
>> 
>> Or we could just not bother giving any formal semantics to any new
>> parts that are added to RDF. Several parts of RDF don't have a formal
>> semantics and work pretty much fine anyways, e.g., RDF lists.
> 
> Yes we could do that but the reason why I want to have a formal semantics is that you can then build on top of it without having to redefine the common ground over and over again. It's like RDF: the semantics of the RDF vocabulary is very very weak and not quite useful at all. But you can build RDFS on top of it, then OWL, with a common ground (although OWL DL is departing from this idea).
> 
>> 
>> Best, Richard
>> 
> 
> -- 
> Antoine Zimmermann
> ISCOD / LSTI - Institut Henri Fayol
> École Nationale Supérieure des Mines de Saint-Étienne
> 158 cours Fauriel
> 42023 Saint-Étienne Cedex 2
> France
> Tél:+33(0)4 77 42 83 36
> Fax:+33(0)4 77 42 66 66
> http://zimmer.aprilfoolsreview.com/
> 
> 

------------------------------------------------------------
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
Received on Tuesday, 20 December 2011 18:54:52 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:25:46 GMT