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Re: Question about literals in subject position

From: Ivan Herman <ivan@w3.org>
Date: Thu, 01 Oct 2009 10:04:27 +0200
Message-ID: <4AC4628B.4070004@w3.org>
To: "Seaborne, Andy" <andy.seaborne@hp.com>
CC: Paul Gearon <gearon@ieee.org>, "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>


Seaborne, Andy wrote:
>>
>> Thinking this way is why I suggest that SPARQL need not make any
>> notion of literal subjects completely illegal. If they're allowed,
>> then they work perfectly with RDF as it stands. Even if allowing
>> literal subjects (especially through variable bindings) disagrees with
>> SPARQL 1.0, I don't believe it does so in a way that would impact any
>> existing systems. Indeed, some systems explicitly ignore the spec in
>> this regard.
> 
> In SPARQL Query 1.0, literals subjects are just fine.
> 
> [[
> Definition: Triple Pattern
> 
> A triple pattern is member of the set:
> (RDF-T union V) x (I union V) x (RDF-T union V)
> ]]
> 
> [[
> "[The RDF core Working Group] noted that it is aware of no reason why literals should not
>   be subjects and a future WG with a less restrictive charter may
>   extend the syntaxes to allow literals as the subjects of statements."
> ]]
> 
> It's the graph data that introduces the restriction.
> 
> 	Andy
>

Ah, I was looking for this because I remembered it was there at some
point, but I did not find it. I presume I will have to change my glasses
(or my head, but that is more difficult):-)

But that means that the SPARQL group already made the choice for us in
the past, in the sense of trying to be 'future proof' as we called it.
That also means that we should probably follow suit and be 'future
proof' in the entailement regime issues, too...

Ivan



>> Paul
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
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Received on Thursday, 1 October 2009 08:04:50 GMT

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