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RE: Next telecon features & beyond

From: Orri Erling <erling@xs4all.nl>
Date: Sun, 15 Mar 2009 23:08:03 +0100
Message-Id: <200903152209.n2FM98oE046709@smtp-vbr17.xs4all.nl>
To: "'Steve Harris'" <steve.harris@garlik.com>, "'SPARQL Working Group'" <public-rdf-dawg@w3.org>


-----Original Message-----
From: public-rdf-dawg-request@w3.org [mailto:public-rdf-dawg-request@w3.org]
On Behalf Of Steve Harris
Sent: Saturday, March 14, 2009 12:46 AM
To: SPARQL Working Group
Subject: Re: Next telecon features & beyond

On 13 Mar 2009, at 19:36, Lee Feigenbaum wrote:

> Alexandre Passant wrote:
>> Without any pathLength filtering, the query is simply a property  
>> path query as proposed in [3], but that way of using a variable  
>> (rather than including the regexp directly as in ":foo rdf:type/ 
>> rdfs:subClassOf* :bar") allows imho more extensibility, especially  
>> for that length feature.
>
> Right, but [3] doesn't include variables in the path position.  
> Putting my implementer's hat on, I think that allowing path  
> variables is significantly more challenging to implement, so much so  
> that I'd prefer to consider the two cases separately.

I agree.

- Steve


Hi

Virtuoso has a transitive feature that can deal with path ;lengths and
returning data associated with steps on the path.  Combining this with an
aggregate like SQL's XMLAGG and grouping would allow returning a path as a
single variable binding, now to an XML fragment describing the path.  This
features is a bit complex and I do not consider it probable that the working
group could arrive to consensus regarding it, so standardizing this is not
our top agenda.  But since the matter was brought up, we would refer you to
our  documentation on this.

Ivan, please send the SQL and SPARQL transitivity sections to the list as
attachments or put them on the Virtuoso blog so they can be read.  Since
this is Virtuoso 6 material, it I  not on the main docs site.

Orri



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Steve Harris
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