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Re: SPARQL WG action on property paths

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Thu, 05 Apr 2012 08:12:06 -0400
Message-ID: <4F7D8C16.6080809@thefigtrees.net>
To: W Martens <martens.wim@gmail.com>
CC: jorge.perez.rojas@gmail.com, jeen.broekstra@gmail.com, Marcelo Arenas <marcelo.arenas1@gmail.com>, Sebastián Conca <sconca87@gmail.com>, www-archive@w3.org, Axel Polleres <axel@polleres.net>
Hi Wim,

Unfortunately, I'm not in a position to represent the entire group in 
discussing the various motivations behind this particular design 
decision. As I told Marcelo, if the group proceeds with this design, you 
will of course have every opportunity to share comments on it with the 
group and to object to the specification proceeding should you wish.

For now, I'm simply seeking to understand if the design that the group 
has agreed on addresses your concern about property paths being "hard to 
evaluate" as you expressed in 


On 4/5/2012 3:51 AM, W Martens wrote:
> Dear Lee,
> thank you very much for keeping us up to date. This is really appreciated.
> I have read the proposal and I also already read Marcelo's answer.
> I would like to make two remarks:
> (1) My first remark is an agreement to what Marcelo says. I also think
> that it is unnatural to say that one needs to count for some operators
> and one does not need to for others. In his example, Marcelo really
> hits the nail on the head by showing how the use cases can be easily
> addressed by pure existential semantics.
> (2) Furthermore, I think that it would be a pity to implement 6.D.,
> that is, to remove the {} forms: {n}, {n,m}, {n,}, {,m}. The reason is
> that these operators make property paths quite a bit more powerful and
> can be implemented at virtually no extra cost, by a very simple
> algorithm (which is presented in the PODS 2012 paper).
> Best regards,
> Wim
> On Tue, Apr 3, 2012 at 5:19 PM, Lee Feigenbaum<lee@thefigtrees.net>  wrote:
>> Hi Wim, Jorge, Jeen, Marcelo, and Sebastian,
>> (Please note that this is not an official working group response to your
>> respective comments on property paths in the current SPARQL 1.1 Query last
>> call working draft.)
>> I want to thank you all again for your research, experiences, suggestions,
>> and comments on SPARQL 1.1 property paths. They've been very valuable to the
>> working group.
>> The group has spent some time in the past few weeks considering various
>> options in an attempt to address the implementation and evaluation
>> challenges that you have all raised while still respecting our group's
>> schedule, implementers' burdens, and the use cases we've identified for
>> property paths.
>> Today, we reached consensus within the group on an approach that we feel
>> addresses your concerns while still leaving room for implementation
>> experience going forward to inform additional design decisions in the
>> future.
>> We haven't yet worked this design into the query document, which is why this
>> isn't an official WG response to your comments. Yet before we go ahead and
>> publish a new Last call, we'd like to know if you support this new design
>> and if you believe that it does indeed address your comments.
>> The design is summarized in these two emails by Andy Seaborne:
>> http://lists.w3.org/Archives/Public/public-rdf-dawg/2012JanMar/0285.html
>> http://lists.w3.org/Archives/Public/public-rdf-dawg/2012JanMar/0286.html
>> I'd very much appreciate it if you can take a look at this and let me know
>> what you think.
>> thanks,
>> Lee
Received on Thursday, 5 April 2012 12:13:00 UTC

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