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Re: Turtle - Terse RDF Triple Language updated

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Sat, 06 Oct 2007 06:49:14 -0400
Message-ID: <4707682A.9040505@ibiblio.org>
To: Ivan Herman <ivan@w3.org>
Cc: Alan Ruttenberg <alanruttenberg@gmail.com>, Story Henry <henry.story@bblfish.net>, Dave Beckett <dave@dajobe.org>, Michael Schneider <schneid@fzi.de>, semantic-web@w3.org

Ivan Herman wrote:
> Alan Ruttenberg wrote:
>   
>> On Oct 5, 2007, at 3:05 PM, Tim Berners-Lee wrote:
>>
>>     
>>> :Joe   :aunt [ is :Sally;   age 78 ].
>>>       
>> Does this generate 2 or 3 triples? 
>>     
>
> At present, this generates three triples using a blank node.
>
>   
>>                                     Henry's note suggests that it should
>> generate 2, as he is using the notation as shorthand. 
>> In other words, parsing this should not generate any blank nodes.
>> I would support that interpretation, which I think would need to be
>> documented.
>> It would be a shame to generate bnodes as a consequence of solely
>> wanting an abbreviation.
>>     
>
> If we change this interpretation we would get ourselves into a major
> incompatibility with SPARQL. That makes me nervous.
>   
I mean, I'm pretty sure that generates 3 triples in N3 [1], so N3/Turtle
is consistent with SPARQL

In SPARQL[2], [] is used for blank nodes, and  [ :p "v" ] as shorthand
for [] :p "v".  Wherever you have   [ :p "v" ]  you have no subject, and
so of course it's subject is a blank node. Same with N3 [1] - as in
"<#pat> <#child> [ <#age> 4 ] , [ <#age> 3 ]" means <#pat> <#child>
_:a,<#pat> <#child> _:b,
_:a <#age> 4 , _:b <#age> 3 from the N3 Primer.

So perhaps I just haven't had my morning coffee yet, but what 2 triples
should be generated in Henry's example? :Joe :aunt :Sally, :Sally :age
78? If that's all you want, then run Turtle+entailment, right?

Regardless, as for features like "=" - yes, of course they are useful.
However, I think the obvious thing to do is to keep Turtle and N3 syntax
separate, with N3 syntax being a superset of Turtle. So, keep Turtle 1
to 1 with SPARQL, and then have N3 have things like "=" in it.

However, the first hurdle is clearly getting Turtle stable, which it (at
least to me) seems more or less.

[1] http://www.w3.org/2000/10/swap/Primer
[2] http://www.w3.org/TR/rdf-sparql-query/
> Ivan
>
>
>   
>> -Alan
>>
>> On Oct 3, 2007, at 10:36 AM, Story Henry wrote:
>>
>>     
>>> :me foaf:knows [ owl:sameAs <http://www.w3.org/People/Connolly/#me>;
>>>
>>>                  a foaf:Person;
>>>
>>>                  foaf:name "Dan Connolly" ] .
>>>
>>>
>>> That saves me having to look around the file for the info, and it also
>>> save me having to type a URL twice, which is more likely to cause a bug.
>>>
>>>
>>> If I don't do that I would have to write
>>>
>>>
>>> :me foaf:knows <http://www.w3.org/People/Connolly/#me>.
>>>
>>> <http://www.w3.org/People/Connolly/#me> a foaf:Person;
>>>
>>>                                         foaf:name "Dan Connolly"  .
>>>
>>>       
>
>   


-- 
		-harry

Harry Halpin,  University of Edinburgh 
http://www.ibiblio.org/hhalpin 6B522426
Received on Saturday, 6 October 2007 10:49:24 GMT

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