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Comment on Entailment Regimes

From: Svensson, Lars <L.Svensson@dnb.de>
Date: Thu, 16 Feb 2017 09:25:29 +0000
To: "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
Message-ID: <24637769D123E644A105A0AF0E1F92EF010D2BC61C@dnbf-ex1.AD.DDB.DE>
Hello all,

Looking at the current editor's draft [1] I have a question / comment on the use of entailment in SHACL processing.

§1.5 [2] states normatively that "SHACL uses the RDF and RDFS vocabularies, but full RDFS inferencing is not required" and then goes on _non-normatively_ to talk about the property sh:entailment and how SHACL processors may support RDFS entailment (or any other kind of entailment).

When I first read this, I felt confused since the normative part says that RDFS inferencing is not required but that SHACL processors MAY support it, leaving me wondering if that meant that different processors might come to different results depending on whether they support inferencing or not. The answer came further down in Appendix A [3] where it is stated that "if an entailment regime is provided in the shapes graph which is not supported by the SHACL processor, the validation MUST produce a failure" which is clear enough.

I would find it easier for the reader, though, if you would remove Appendix A and move its contents to §1.5 so that you have all the information about entailment in one place. Further, there seems to be no formal definition of sh:entailment in the document. The property is only mentioned in the non-normative part of §1.5 and in Appendix A (which I don't know if it's normative or not: Are appendices normative?). I guess that it is (theoretically) possible to ask the SHACL processor to use more than one entailment regime (e. g. RDFS [4] and D-entailment [5]) but that the support of that is implementation-specific. It would help, though, if there were a (non-normative) note about that in the spec, too.

[1] https://w3c.github.io/data-shapes/shacl/

[2] https://w3c.github.io/data-shapes/shacl/#shacl-rdfs

[3] https://w3c.github.io/data-shapes/shacl/#entailment

[4] https://www.w3.org/TR/sparql11-entailment/#RDFSEntRegime

[5] https://www.w3.org/TR/sparql11-entailment/#DEntRegime


Thanks,

Lars

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Received on Thursday, 16 February 2017 09:26:07 UTC

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