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Re: SPARQL paths and N3 paths: some quick thoughts.

From: Dan Connolly <connolly@w3.org>
Date: Tue, 26 Jan 2010 09:17:38 -0600
To: Tim Berners-Lee <timbl@w3.org>
Cc: public-cwm-talk@w3.org
Message-ID: <1264519058.28820.2404.camel@pav.lan>
On Tue, 2010-01-26 at 12:39 +0100, Tim Berners-Lee wrote:
> Paths have been in N3 for a long time and much
> discussed.
> 
> The characters used are "!" and "^".
> A discussion of the options is in 
> http://www.w3.org/DesignIssues/N3Alternatives#Syntax
> 
> It would be a really bad idea not to use the same punctuation in SPARQL.
> 
> Could you pass that on?

As the message from Any shows, the WG is aware of N3 path syntax.

I'm not sure I agree N3 paths have been "much discussed",
and using / seems quite reasonable to me.

> 
> Tim
> 
> PS: Note also ^ is related to ^^ in that ^^ can be regarded 
> as ^ if you want to reify datatypes -- to make an RDF
> system which uses only strings.
> 
> On 2010-01 -22, at 22:10, Dan Connolly wrote:
> 
> > The SPARQL WG is looking at paths...
> > http://www.w3.org/2009/sparql/docs/property-paths/Overview.xml
> > 
> > ... which is quite important for querying, e.g. lists:
> > 
> > select ?elt where { <alist> rdf:rest*/rdf:first ?elt }
> > 
> > Meanwhile, they're using / where n3 uses ., I think.
> > 
> > They use ^ both as N3 uses it and to do the is/of thing.
> > 
> > They also include regex syntax such as +,*, ? and {n,m}
> > and ()s (but not for match groups).
> > 
> > It's pretty hard to argue against this in SPARQL; people
> > have been asking for it from the very start of the SPARQL
> > design.
> > 
> > Perhaps N3 should adapt in this direction?
> > 
> > The one place I'm inclined to push on is is/of; I'd
> > hate to lose that from N3. Though... with the @keywords
> > mechanism, maybe it's not so much of a conflict.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
gpg D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Tuesday, 26 January 2010 15:17:40 GMT

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