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Re: comments on SHACL Core Abstract Syntax and Semantics

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Sat, 27 Aug 2016 11:55:31 -0700
To: kcoyle@kcoyle.net, public-rdf-shapes@w3.org
Message-ID: <478bd430-ec89-7ff3-fc1d-2dd97610978e@gmail.com>
Yes I mean the English language descriptions of the meanings of the various
constructs.   This provides a semantics for SHACL, albeit an informal one.

Examples of syntax are examples of syntax, i.e., not semantic.  Providing an
informal description of these examples is semantics of a sort, but saying what
an example means is generally considered to not to have any normative force.


On 08/27/2016 08:46 AM, Karen Coyle wrote:
> Thank you, Peter, these are great comments. We'll incorporate as many as we
> can into the next version of the document.
> I do have a question about your use of the term "semantics" because it may be
> different from mine. By "semantics" do you mean the English-language
> explanations of the syntax? And if so, does that also include the examples?
> Thanks again,
> kc
> On 8/26/16 11:09 AM, Peter F. Patel-Schneider wrote:
>> Some comments on SHACL Core Abstract Syntax and Semantics first public
>> working draft 25 August 2016 at https://www.w3.org/TR/shacl-abstract-syntax/
>> There is a discrepancy between the title and abstract of the document.  The
>> title includes semantics but the abstract only talks about syntax.  The
>> document should be clear at the beginning about what it covers.
>> The body of the document does talk about the semantics of SHACL.  There is
>> already a semantics provided for SHACL in https://www.w3.org/TR/shacl/.
>> There does not appear to be any reason to have two different documents that
>> provide a semantics for SHACL, even with one of them being non-normative.
>> As there is no reason for a second version of the semantics of SHACL it
>> needs to be removed from this document.
>> The document appears to provide an abstract syntax for SHACL.  The abstract
>> and title say "core SHACL" but there is no discussion in the body of the
>> document as to just what is being covered.  If the document is just covering
>> the core of SHACL it needs to qualify what it is doing throughout the body
>> of the document.
>> The document does not even cover all of the core of SHACL.  For example, it
>> does not provide for severities or any of the non-validating aspects of
>> SHACL shapes.  This needs to be remedied or explained.
>> The document uses "SHACL instance graph".  This is probably referring to a
>> shapes graph and thus probably needs to be changed.  Instance graphs,
>> however, contain schemas, which are not defined for SHACL.
>> The document uses RDF Semantics as its source of definitions for some RDF
>> notation.  It would be better to reference RDF 1.1 Concepts and Abstract
>> Syntax where possible.
>> I think that the document in its current form has negative utility.  The
>> abstract syntax does not correspond to any coherent part of SHCL.  The
>> semantics is just going to be a competitor to the informal and formal
>> semantics in https://www.w3.org/TR/shacl/.  If the semantics stuff was
>> removed and the abstract syntax actually corrsponded to the SHACL core
>> syntax then there might be some small utility for the document.
>> Peter F. Patel-Schneider
>> Nuance Communications
Received on Saturday, 27 August 2016 18:56:03 UTC

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