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Re: shapes-ISSUE-146 (sh:qualifiedMinCount ): treatment of unbound results from sh:hasShape in sh:qualifiedMinCount (and elsewhere) [SHACL - Core]

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Thu, 21 Apr 2016 03:53:09 -0700
To: Holger Knublauch <holger@topquadrant.com>, public-data-shapes-wg@w3.org
Message-ID: <5718B115.9010303@gmail.com>
The handling of ?failure in general is not the issue here.  The issue is that
the textual definition indicates that a failure results when there are too few
values for which the shape produces no violation-level validation results or
failures.  However, the code does not add failures to the count but instead
propagates them.

peter


On 04/21/2016 02:33 AM, Holger Knublauch wrote:
> The updated version of the spec clarifies the handling of the ?failure variable.
> 
> Sigh, we really need more test cases to make sure we are agreeing on the right
> thing...
> 
> Then, in this particular case I am not sure whether QCRs will remain in the
> spec at all, given that we have the sh:partition proposal.
> 
> Holger
> 
> 
> On 15/04/2016 4:10, Peter F. Patel-Schneider wrote:
>> The text indicates that errors are counted, but the code appears to propagate
>> them.
>>
>> peter
>>
>>
>> On 04/10/2016 04:23 PM, Holger Knublauch wrote:
>>> I believe the query is correct, but I have added a paragraph to make it a bit
>>> clearer:
>>>
>>> Note that in the SPARQL query above, we assume that the |SUM| operation fails
>>> if one of the values of |?s| is not a number. This mechanism is used by the
>>> error handling, which sets |?s| to the string |'error'| whenever one of the
>>> individual |sh:hasShape| calls fails.
>>>
>>> HTH
>>> Holger
>>>
>>>
>>> On 9/04/2016 7:11, RDF Data Shapes Working Group Issue Tracker wrote:
>>>> shapes-ISSUE-146 (sh:qualifiedMinCount ): treatment of unbound results
>>>> from sh:hasShape in sh:qualifiedMinCount (and elsewhere) [SHACL - Core]
>>>>
>>>> http://www.w3.org/2014/data-shapes/track/issues/146
>>>>
>>>> Raised by: Peter Patel-Schneider
>>>> On product: SHACL - Core
>>>>
>>>> It's hard to determine just what is going on in the SPARQL code, but
>>>> appears that if any call to hasShape returns unbound then a validation
>>>> result will be produced, which does not match the text.
>>>>
>>>>
>>>> TEXTUAL DEFINITION of sh:qualifiedMinCount
>>>> A validation result must be produced if the number of triples that have
>>>> the focus node as its subject, the sh:predicate as its predicate and where
>>>> validating the object against the shape specified by
>>>> sh:qualifiedValueShape produces no validation results with severity
>>>> sh:Violation or a failure is less than sh:qualifiedMinCount. The produced
>>>> validation result must have the focus node as its sh:subject, and the
>>>> sh:predicate as its sh:predicate.
>>>> SPARQL DEFINITION of sh:qualifiedMinCount
>>>>
>>>> SELECT $this ($this AS ?subject) $predicate ?failure
>>>> WHERE {
>>>>     {
>>>>         SELECT (SUM(?s) AS ?count)
>>>>         WHERE {
>>>>             {
>>>>                 FILTER NOT EXISTS { $this $predicate ?value } .
>>>>                 BIND (0 AS ?s) .
>>>>             }
>>>>             UNION
>>>>             {
>>>>                 $this $predicate ?value .
>>>>                 BIND (sh:hasShape(?value, $qualifiedValueShape,
>>>> $shapesGraph) AS ?hasShape) .
>>>>                 BIND (IF(bound(?hasShape), IF(?hasShape, 1, 0), 'error')
>>>> AS ?s) .
>>>>             }
>>>>         }
>>>>     }
>>>>     BIND (!bound(?count) AS ?failure) .
>>>>     FILTER IF(?failure, true, ?count < $qualifiedMinCount) .
>>>> }
>>>>
>>>>
>>>>
>>>>
>>>>
> 
> 
Received on Thursday, 21 April 2016 10:53:39 UTC

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