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Re: TriG/N3 compatibility was: Named Graph Serialisation

From: Chris Bizer <chris@bizer.de>
Date: Fri, 27 Jul 2007 22:08:43 +0200
Message-ID: <009301c7d089$eeb2ca20$c4e84d57@named4gc1asnuj>
To: "pat hayes" <phayes@ihmc.us>, "Sandro Hawke" <sandro@w3.org>, "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: "Tim Berners-Lee" <timbl@w3.org>, <semantic-web@w3.org>, "Richard Cyganiak" <richard@cyganiak.de>, "Arjohn Kampman" <arjohn.kampman@aduna-software.com>

> I think the right choice is "=", because (as I understand it), that has
> the right semantics.  But maybe I don't know what semantics you want.

Seen from today's perspective, I clearly want the graphname URI to refer to 
a graph one would expect to get by dereferencing this URI and many people 
use the Named Graphs data model exactly in this way.

But the original Named Graphs paper say something different.

Maybe it was a good idea of the SPARQL working group to leave this point 
open when defining their RDF dataset and it would be harmful for Named Graph 
deployment if we would take a decision one or the other way.

Pat, Jeremy, Patrick (and anybody else): What do you think?



Chris Bizer
Freie Universitšt Berlin
+49 30 838 54057
----- Original Message ----- 
From: "Sandro Hawke" <sandro@w3.org>
To: "Chris Bizer" <chris@bizer.de>
Cc: "Tim Berners-Lee" <timbl@w3.org>; <semantic-web@w3.org>; "Jeremy 
Carroll" <jjc@hpl.hp.com>; "pat hayes" <phayes@ihmc.us>; "Richard Cyganiak" 
<richard@cyganiak.de>; "Arjohn Kampman" <arjohn.kampman@aduna-software.com>
Sent: Friday, July 27, 2007 9:43 PM
Subject: TriG/N3 compatibility was: Named Graph Serialisation

> "Chris Bizer" <chris@bizer.de> writes:
>> Hi Tim,
>> > Making the predicate optional, and omitting the final "." messes up =
>> the compatibility.  Two small changes!=20
>> The predicate is optinal and there is no final "." because N3 and TriG =
>> are based on very different abstract models. In N3 you have the notion =
>> of a outer document that contains formulas. Therefore you want the final 
>> =
>> "." The abstract model behind TriG is the Named Graph data model and in =
>> newer versions also the SPARQL dataset. Both abstract model do not have =
>> any notion an outer document and therefore the final "." is missing in =
>> TriG.=20
>> The TriG specification =
>> (http://sites.wiwiss.fu-berlin.de/suhl/bizer/TriG/) allows the use of =
>> the shorthand :- for compatibility reasons with N3 (I think Jeremy =
>> Caroll or Pat Hayes wanted it in as an option, I can not remember). We =
>> overlooked the final "." thing, so the :- option actually does not make =
>> TriG N3 compartible.=20
>> I'm open to adding the final "." as an option, so that future versions =
>> of TriG parsers can read N3. I'm not too sure about making both things =
>> mandatory, as N3 and TriG really have different abstract models.
>> Any strong opinions on this from anybody? Especially from the people who 
>> =
>> have implemented TriG parsers and would have to change their code.
> ... random comments from the peanut gallery:
> I think y'all should converge on one syntax.  The difference between the
> N3 model and the TriG model needs to be settled anyway.
> I think :- is a poor choice of operators here.  To many of us with some
> experience with prolog it's the rule connective.
> I think the right choice is "=", because (as I understand it), that has
> the right semantics.  But maybe I don't know what semantics you want.
>      -- Sandro 
Received on Friday, 27 July 2007 20:08:41 UTC

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