W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > October to December 2009

RE: Question about literals in subject position

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Thu, 1 Oct 2009 11:22:12 +0000
To: Ivan Herman <ivan@w3.org>
CC: Paul Gearon <gearon@ieee.org>, "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
Message-ID: <B6CF1054FDC8B845BF93A6645D19BEA3693EA8E1D6@GVW1118EXC.americas.hpqcorp.net>


> -----Original Message-----
> From: Ivan Herman [mailto:ivan@w3.org]
> Sent: 01 October 2009 09:04
> To: Seaborne, Andy
> Cc: Paul Gearon; public-rdf-dawg@w3.org Group
> Subject: Re: Question about literals in subject position
> 
> 
> 
> 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):-)

I wasn't in the spec where I though it was :-)

> 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...

Agreed, although the credit for the future proofing goes to RDF core.

(Blank node predicates do not follow automatically.)

	Andy

Received on Thursday, 1 October 2009 11:23:40 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:40 GMT