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Re: Order of filters (was: Quick Comments on https://www.w3.org/TR/2016/WD-shacl-20160814/)

From: Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>
Date: Fri, 23 Sep 2016 13:45:13 +0200
Message-ID: <CA+u4+a3xBwpDKhkN6OxT1pdYfOakJQrJg=sYqEv0S_xxWWyy_w@mail.gmail.com>
To: Holger Knublauch <holger@topquadrant.com>
Cc: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, "public-rdf-sha." <public-rdf-shapes@w3.org>
>From what I remember,

Peter suggested that we are able to switch the order of validation and
filtering in case filtering is very expensive and perform the filtering on
fewer focus nodes
At that time, failure in the validation was not noted as a possible problem
and I relaxed the order.
Since this may introduce undesired results I think it is safer to force the
order as suggested by Holger

Best,
Dimitris.

On Fri, Sep 23, 2016 at 7:09 AM, Holger Knublauch <holger@topquadrant.com>
wrote:

> On 23/09/2016 11:36, Peter F. Patel-Schneider wrote:
>
>>
>> order of processing for filters
>>>
>>> The discussion of how filters are processed appears to be contradictory.
>>>
>> First there is: "SHACL validation engines MAY alter the order of the
>> depicted steps as long as the returned validation results are correct."
>> Later there is: "Filter shapes MUST be evaluated before validating the
>> associated shapes or constraints."
>>
>>>      Comment (HK): Yes, the first sentence is IMHO incorrect and I have
>>>
>> taken it out
>> (https://github.com/w3c/data-shapes/commit/3777e8e80aec9f9c1
>> ba1bbb0dfdfce2b2acb9a12).
>> The problem is that if an engine does filtering after validation, it may
>> run
>> into a failure that is otherwise not reached. I don't remember why we
>> added
>> that statement in the first place, do you @Dimitris?
>>
>>>      Comment (DK): This was changed to address a comment from Peter on
>>>
>> March 7th and resulted in this commit
>>
>> This appears to be two different responses.  What is the situation?
>>
>
> Dimitris is this something you could clarify? I don't remember the history
> of that topic.
>
> Thanks
> Holger
>
>


-- 
Dimitris Kontokostas
Department of Computer Science, University of Leipzig & DBpedia Association
Projects: http://dbpedia.org, http://rdfunit.aksw.org,
http://aligned-project.eu
Homepage: http://aksw.org/DimitrisKontokostas
Research Group: AKSW/KILT http://aksw.org/Groups/KILT
Received on Friday, 23 September 2016 11:46:10 UTC

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