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Re: on evaluation

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Wed, 28 Sep 2016 15:09:23 -0700
To: kcoyle@kcoyle.net, public-rdf-shapes@w3.org
Message-ID: <67cfdfbf-3c60-1201-2634-c8d510d0f053@gmail.com>
So, yes, I have two problems with the current wording:

1/ It is yet another case of loose terminology.
2/ It is the wrong way to do things.

There are two reasons that it is wrong:
a) It prevents optimization of the SPARQL processing.
b) It even prevents translation of entire SHACL shapes to single SPARQL
queries, *requiring* something like sh:hasShape in *every* SHACL implementation.

I think that the order in which I discovered these issues was 2a, then 1, then
2b.

The net result is that I believe that the entire sentence needs to be
completely scrapped, and thus I don't see that there is any utility in
wordsmithing the sentence to fix problem 1.

Peter F. Patel-Schneider
Nuance Communications


On 09/28/2016 02:41 PM, Karen Coyle wrote:
> Oh, I should have included the link to the diagram:
> 
> https://www.w3.org/TR/2016/WD-shacl-20160814/images/SHACL-Validation-Process.png
> 
> That's a quick read. - kc
> 
> On 9/28/16 2:38 PM, Karen Coyle wrote:
>>
>>
>> On 9/28/16 1:56 PM, Peter F. Patel-Schneider wrote:
>>> My view is that there should be no requirement that focus nodes are
>>> validated
>>> against the filter shapes of a shape before they are validated against
>>> the
>>> constraints of the shape.  I have previously mentioned several reasons
>>> that
>>> led me to this view.
>>
>> OK. This is a different objection to what I had previously understood. I
>> thought your objection was to saying that they are "validated".
>>
>> In the introduction to section 2.0 of SHACL there is a diagram that
>> shows what I have taken to be an execution flow:
>>
>> data graph -> targets are used to select focus nodes -> Filters are used
>> to eliminate some focus nodes -> Constraints are used to produce
>> validation results.
>>
>> Is it this flow that you are objecting to?
>>
>> If so, can you either point to or reiterate your reasons?
>>
>> Thanks,
>> kc
>>
>>
>>>
>>> Peter F. Patel-Schneider
>>> Nuance Communications
>>>
>>>
>>> On 09/28/2016 06:40 AM, Karen Coyle wrote:
>>>> Peter, how would you describe the action that takes place then?
>>>> Because there
>>>> is an implied action and work flow. Implemented? executed? enforced?
>>>> resolved?
>>>> (I'm running through the thesaurus entries.)
>>>>
>>>> kc
>>>>
>>>> On 9/27/16 3:43 PM, Peter F. Patel-Schneider wrote:
>>>>> For starters, filter shapes are not "applied to the data graph", so,
>>>>> no.
>>>>>
>>>>> peter
>>>>>
>>>>>
>>>>> On 09/27/2016 03:38 PM, Holger Knublauch wrote:
>>>>>> Peter, would this suggestion work better for you? I assume someone
>>>>>> could argue
>>>>>> that "applied" is not defined.
>>>>>>
>>>>>> Holger
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 28/09/2016 1:44, Karen Coyle wrote:
>>>>>>> Filter shapes must be ...
>>>>>>>  - applied to the data graph
>>>>>>> ... before validating....
>>>>>>>
>>>>>>>
>>>>>>> On 9/26/16 4:38 PM, Holger Knublauch wrote:
>>>>>>>> Does anyone else find this sentence unclear? If yes, could someone
>>>>>>>> suggest alternative wording?
>>>>>>>>
>>>>>>>> "Filter shapes MUST be validated before validating the associated
>>>>>>>> shapes
>>>>>>>> or constraints."
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Holger
>>>>>>>>
>>>>>>>>
>>>>>>>> On 27/09/2016 1:52, Peter F. Patel-Schneider wrote:
>>>>>>>>> How is a shape "validated"?
>>>>>>>>>
>>>>>>>>> This problem even affects the second half of the sentence I
>>>>>>>>> initially
>>>>>>>>> quoted.
>>>>>>>>>
>>>>>>>>> peter
>>>>>>>>>
>>>>>>>>> On 09/26/2016 12:18 AM, Holger Knublauch wrote:
>>>>>>>>>> Replaced with "validated":
>>>>>>>>>>
>>>>>>>>>> https://github.com/w3c/data-shapes/commit/d4fbdebd7044cd79f35985a75a54994ea3facde9
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Holger
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 26/09/2016 15:59, Peter F. Patel-Schneider wrote:
>>>>>>>>>>> "Filter shapes MUST be evaluated before validating the associated
>>>>>>>>>>> shapes or
>>>>>>>>>>> constraints."
>>>>>>>>>>>
>>>>>>>>>>> Evaluation is not defined.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> peter
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
> 
Received on Wednesday, 28 September 2016 22:09:56 UTC

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