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Re: on constraints

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Fri, 30 Sep 2016 06:48:51 -0700
To: Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>
Cc: "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
Message-ID: <65238cb2-194a-9428-aecd-2a3776168f03@gmail.com>
If you remember, it used to be that constraint parameters could not be
directly attached to shapes.  Instead there had to be a "local constraint"
atttached to the shape and then constraint parameters were attached to that.

Now instead constraint parameters (*not* constraints) are attached directly to
shapes and the shape itself takes the role that used to be played by the
"local constraint".

Even the use of "attach" is dodgy here.  Attached how?  It is better to talk
about triples with a particular subject, object, and predicate.  Shorthand
constructions may be easier to read as English, but it can easily turn out
that they don't have the necessary precision.

There has also been a terminology shift, again for precision.  The object of
an sh:shape triple is a shape, which is now also a constraint.  So for
sh:shape to group focus node constraints (not constraint parameters) something

  sh:shape [ sh:shape [....] ; sh:shape [...] ]

is required.

At least this is my understanding of the current mechanisms and terminology.

Peter F. Patel-Schneider
Nuance Communications

On 09/30/2016 01:43 AM, Dimitris Kontokostas wrote:
> Thank you for the feedback Peter,
> I tried to address some of your comments here:
> https://github.com/w3c/data-shapes/commit/8d8df0e57361558674bd65492cebd9c7358140c7
> On Fri, Sep 30, 2016 at 3:46 AM, Peter F. Patel-Schneider
> <pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>> wrote:
>     "Focus node constraints are attached directly to Shapes"
>     Not any more.
>     "sh:shape can be used to group focus node constraints."
>     Not any more, except by using sh:shape itself, I guess.
> Can you please elaborate a bit further on these two comments?
> Best,
> Dimitris
Received on Friday, 30 September 2016 13:49:20 UTC

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