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RE: Turtle - Terse RDF Triple Language updated

From: Michael Schneider <schneid@fzi.de>
Date: Fri, 5 Oct 2007 10:57:26 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A040A67B@judith.fzi.de>
To: "Tim Berners-Lee" <timbl@w3.org>
Cc: <semantic-web@w3.org>, "Dave Beckett" <dave@dajobe.org>, "Story Henry" <henry.story@bblfish.net>

TimBL wrote:

>On 2007-10 -03, at 06:55, Story Henry wrote:
>
>>
>> On 3 Oct 2007, at 12:41, Michael Schneider wrote:
>>
>>> Henry Story wrote:
>>>
>>>> What about =
>>>>
>>>> That would be a nice addition. :-)
>>>>
>>>> Especially as it allows one to group statements together like this:
>>>>
>>>> :me foaf:knows [ = <http://eg.com/joe/>;
>>>>                  foaf:name "Joe Smith" ] .
>>>>
>>>
>>> Just for me to understand: Is this meant to be a shortcut for  
>>> 'owl:sameAs'?
>>
>> Yep! It's that obvious :-)
>>
>
>Yes.  It is only allows as a predicate, you can't say   = s:label  
>"same as".
>I agree it is very useful.

Me too.

But doesn't anyone feel inconvenient with the idea of making Turtle
dependent on OWL vocabulary? I thought that Turtle has been intended to be a
pure RDF serialization?  Ok, one could say that 'owl:sameAs' is just some
URI, which happens to share its namespace prefix with that of OWL... would
be an opinion.

Now while I think about this: Why is there no 'rdf:sameAs' in RDF? Equality
is such a fundamental concept. And RDF does not have a unique name
assumption, so a 'sameAs' property in RDF would have a real benefit, because
it would allow me to explicit state that two different URIs are intended to
denote the same resource. I have often seen people in this mailing list
using or referring to 'owl:sameAs' for expressing equality in "pure" RDF
(non-OWL) related discussions. But what did these people do before OWL? 

Ah, perhaps they applied the analog DAML [1] concept? But when I look at
this old ontology language, there was a clear distinction between sameness
for individuals, classes and properties. Such a separation would probably
not be perfectly appropriate for RDF. So has it been anticipated that there
will, in the future, be some general equality concept in one of the more
expressive ontology languages? Otherwise it would look to me as if we had a
little "luck" that such a concept was finally introduced in OWL, many years
after RDF had been standardized.

Of course, if there really was an 'rdf:sameAs' in RDF, one would than also
have to think about supporting 'sameAs' in RDF-S, too, as a reasoning
feature (not necessarily of course, I know). And this might have led to some
difficulties. So 'sameAs' might really have been /intentionaly/ left out of
RDF in favour of an analog OWL concept in the future. Any SemWeb historian
here, who can explain this to me? 

Well, just a few weakly connected thoughts, which came to my mind, when
thinking about "=" in Turtle. :)

Cheers,
Michael

[1] DAML ontology language: 
    http://www.daml.org/2001/03/daml+oil

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
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Email: Michael.Schneider@fzi.de
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Received on Friday, 5 October 2007 08:57:51 GMT

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