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Re: recursive shapes in SHACL

From: Richard Cyganiak <richard@cyganiak.de>
Date: Wed, 25 Mar 2015 14:40:30 +0000
Cc: "public-data-shapes-wg@w3.org" <public-data-shapes-wg@w3.org>
Message-Id: <8FE36BC3-2BAD-425E-910E-24C0B90D23C8@cyganiak.de>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>

> On 24 Mar 2015, at 15:35, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote:
> 
> I believe that the current design of SHACL
> (https://w3c.github.io/data-shapes/shacl/) will make recursive shapes very
> problematic.
> 
> Both variations in
> http://w3c.github.io/data-shapes/shacl/#sparql-AbstractValueShapePropertyConst
> raint
> do not work correctly. (Consider how the designs would work on the SHACL
> versions of the examples in
> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2015Mar/0377.html.)
> 
> Does anyone have a proposal on how to handle recursive shapes that does not
> give rise to difficulties?

If SHACL supports levels like ERROR, WARNING, INFO, then another possible design would be that recursive shape definitions are allowed. But when a SHACL processor is asked to validate a graph against such a shape, it produces a report with a special level such as RECURSIVE_SHAPE_NOT_CHECKED.

It may be prudent to say in the spec that recursive shape definitions may only have a level lower than ERROR. So, the author of the SHACL document needs to acknowledge in advance that SHACL processors won’t check this particular part of the constraint by giving it a non-ERROR level.

Richard
Received on Wednesday, 25 March 2015 14:41:03 UTC

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