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Re: RDF Data Shapes WG agenda for 8 October 2015

From: Karen Coyle <kcoyle@kcoyle.net>
Date: Thu, 8 Oct 2015 10:17:20 -0700
To: public-data-shapes-wg@w3.org
Message-ID: <5616A520.50507@kcoyle.net>

On 10/8/15 5:53 AM, Peter F. Patel-Schneider wrote:

> ISSUE-91
> As I indicated last week, in
> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2015Oct/0004.html,
> I vote +1 for resolving ISSUE-91 in a way that does not require default values
> for cardinalities, i.e., min 0 and max unbounded. I vote -1 for other ways of
> resolving ISSUE-91.

Well, what you say there sure sounds like defaults. I think the 
non-default option is that no cardinality processing is done when there 
are no cardinality constraints. That's fine. But there does need to be a 
way to express cardinality constraints that includes min 0 and max 

Note that as regard defaults, we already have a default of "open shapes" 
that cannot be expressed explicitly, which I believe needs to at least 
be made clear in the documentation.


> ISSUE-92
> The proposals for resolving ISSUE-92 suggest that repeated constraints on the
> same property be considered as "additive".  I do not feel that there is much
> evidence to support the need for this reading.  In particular, the example in
> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2015Sep/0107.html
> does not need an additive reading as there is no overlap between the two sets
> of possible values - all that is needed are qualified cardinality constraints
> and a cleanup on constraints to generalize node-based constraints.  A proposal
> for this cleanup is described in ISSUE-98.  I vote for this approach and
> against the other approaches.

The purpose of this is user-facing, not engineering-necessitated. Yes, 
qualified cardinality constraints can be used, but at a human cost, 
since 1) it's not a concept that most folks are aware of or comfortable 
with 2) it appears to require quite a bit more coding.

The idea, as I understood it, was to make SHACL easier to grasp and thus 
more likely to be used.

> ISSUE-93
> I agree that there is a conflation of good style with requirements on SHACL
> shape graphs, particularly for rdfs:label and rdfs:comment.  I also agree that
> good style should not be diluting the requirements for SHACL.
> Separately, I agree that the requirements for SHACL shape graphs and SHACL
> engines are smushed together and that the requirements for SHACL engines
> should be refactored.  I think that the way to do this is to define SHACL
> operations like validation and then describe what implementations of these
> operations must or should or may do.  Validation reports are part of SHACL
> validation, so it is not possible to just define what is required for data to
> satisfy a shape as suggested in
> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2015Sep/0232.html



> ISSUE-94
> I do not feel that there is any need to completely remove the RDF syntax
> definition from the current SHACL document.  I do agree that there should be
> more care taken to discuss SHACL constructs without appearing to require them
> being RDF.  I also agree that the semantics of the constructs should be
> written without depending on the RDF representation of SHACL constructs.
> ISSUE-96
> I feel that SHACL validation results already contain adequate information to
> identify the construct in question.  Adding more information only complicates
> an already-complex system.  I vote -1 for such additions.
> peter

Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600
Received on Thursday, 8 October 2015 17:17:57 UTC

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