W3C home > Mailing lists > Public > public-cwm-talk@w3.org > January to March 2010

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

From: Dan Connolly <connolly@w3.org>
Date: Wed, 27 Jan 2010 12:59:49 -0600
To: public-rdf-dawg-comments@w3.org
Cc: public-cwm-talk@w3.org, Tim Berners-Lee <timbl@w3.org>
Message-ID: <1264618789.28820.2587.camel@pav.lan>
I should have copied the comments list last Friday when I started this
thread...
http://lists.w3.org/Archives/Public/public-cwm-talk/2010JanMar/0002.html


On Tue, 2010-01-26 at 09:17 -0600, Dan Connolly wrote:
> 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 Wednesday, 27 January 2010 18:59:52 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 27 January 2010 18:59:58 GMT