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property path length restrictions [was: Re: A review of extension functions in current implementatations]

From: Christian Chiarcos <chiarcos@informatik.uni-frankfurt.de>
Date: Mon, 08 Apr 2019 11:22:21 +0200
To: public-sparql-12@w3.org
Message-ID: <op.zzo3q00989jat0@kitaba.rz.uni-frankfurt.de>
Dear all,

something I find myself missing almost every time I work with SPARQL is  
the path length feature in the early property graph drafts:
elt{n,m}	A path between n and m occurrences of elt.

What I normally use instead is aggegation and counting of intermediate  
nodes, in order to have it portable, so I didn't check for current  
implementations. Not sure whether this qualifies for the wiki, thus, but  
there used to be implementations 10 years ago:  

The aggregation solution works in most cases (it is slow, though), but  
this is a pain to write and to teach -- and a needless one if path length  
would be implemented just as syntactic sugar for aggregate+count.


Am .04.2019, 23:51 Uhr, schrieb Jeen Broekstra <jeen.broekstra@gmail.com>:

> Thanks for this Jerven.
> I added a short list of things I could think of from the top of my head  
> that RDF4J currently adds as SPARQL extensions. I also mentioned  
> GeoSPARQL for >completeness sake, although I think we should probably  
> consider such an elaborate feature (with its own set of specs) out of  
> scope. Feel free to extend, >correct, or ask for clarification (I've  
> been rather terse in my examples).
> Jeen
> On Thu, Apr 4, 2019 at 5:54 AM Jerven Tjalling Bolleman  
> <Jerven.Bolleman@sib.swiss> wrote:
>> Hi Adrian, Bob, All,
>> I created a wiki page at 
>> https://github.com/w3c/sparql-12/wiki/Inventory-of-existing-extensions-to-SPARQL-1.1
>> That you can start with.
>> Adrian, I added you as a collaborator in case that is needed.
>> Bob, I don't know your github account so please let me know if me or 
>> Andy needs to do some
>> admin work for you.
>> This goes for anyone whom would like to work on this and can't due to
>> permissions.
>> Regards,
>> Jerven
>> On 2019-04-03 19:38, Adrian Gschwend wrote:
>>> On 03.04.19 18:58, bob@snee.com wrote:
>>>Hi Bob,
>>>> Instead of assigning a single person to do an inventory of these
>>>> functions someone (I'd be happy to) could serve as an editor of a
>>>> summary document with content provided by those implementors. If there
>>>> is no place under 
>>>> https://lists.w3.org/Archives/Public/public-sparql-12/
>>>> where we can put a page to store such a document perhaps git would be
>>>> the best place for it.
>>>that definitely makes sense! And if you volunteer you get a +1 from me
>>> :) Would add some stuff I have in mind as well.
>> --Jerven Tjalling Bolleman
>> SIB | Swiss Institute of Bioinformatics
>> CMU - 1, rue Michel Servet - 1211 Geneva 4
>> t: +41 22 379 58 85 - f: +41 22 379 58 58
>> Jerven.Bolleman@sib.swiss - http://www.sib.swiss

Prof. Dr. Christian Chiarcos
Applied Computational Linguistics
Johann Wolfgang Goethe Universitšt Frankfurt a. M.
60054 Frankfurt am Main, Germany

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Received on Monday, 8 April 2019 09:22:52 UTC

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