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Re: behavior of SPARQL-based constraint components using EXISTS

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Tue, 7 Feb 2017 17:07:40 -0800
To: Holger Knublauch <holger@topquadrant.com>, public-rdf-shapes@w3.org
Message-ID: <adc135b3-b307-dc05-15ea-98dc2c650c0b@gmail.com>
Oops.  That should have been:

As it stands right now, no implementation of SPARQL that I know of can be used
in the implementation of SPARQL-SHACL without significant modification because
implementations of SPARQL diverge from the definition of SPARQL.

It is because of this difficulty that the SHACL working group needs to address
the problems with EXISTS.  I have pointed out several options in my initial
message in this thread.


On 02/07/2017 04:56 PM, Holger Knublauch wrote:
> How can this Working Group address a problem in SPARQL? And why should
> implementations of SPARQL implement SHACL?
> Holger
> On 8/02/2017 10:52, Peter F. Patel-Schneider wrote:
>> I don't think that the working group can get away without addressing this
>> problem with SPARQL.  As it stands right now, no implementation of SPARQL that
>> I know of will implement SHACL because they diverge from the definition of
>> peter
>> On 02/07/2017 04:40 PM, Holger Knublauch wrote:
>>> I think this question is orthogonal to SHACL and entirely an issue of the
>>> SPARQL spec. If SPARQL 1.1 gets updated via an erratum then the new semantics
>>> of SPARQL would apply to SHACL too, just like they would apply to any other
>>> technology based on SPARQL. I don't see what we can do about that. As you may
>>> have noticed we have changed the SHACL spec to avoid any use of EXISTS.
>>> Holger
>>> On 8/02/2017 7:33, Peter F. Patel-Schneider wrote:
>>>> What is the behaviour of SPARQL-based constraint components that use EXISTS?
>>>> Is it the broken definition of EXISTS from the SPARQL document?  Is it some
>>>> particular fixed version of EXISTS?  Is it undefined?  Or is EXISTS not to be
>>>> used in SPARQL-based constraint components?
>>>> Peter F. Patel-Schneider
>>>> Nuance Communications
Received on Wednesday, 8 February 2017 01:08:18 UTC

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