Re: On the inevitability of SPARQL/SPIN for SHAQL

On Tue, Mar 3, 2015 at 3:51 AM, Peter F. Patel-Schneider <
pfpschneider@gmail.com> wrote:

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> >> On 02/28/2015 01:51 AM, Jose Emilio Labra Gayo wrote:
> > On Sat, Feb 28, 2015 at 1:54 AM, Peter F. Patel-Schneider
> > <pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>> wrote:
> >
> > I think that it is about time to accept the fact that SHAQL is going to
> > be based on SPARQL and look a lot like SPIN.  This is not my preferred
> > outcome from the working group, but I can live with it in the absence of
> > anything better.
> >
> >
> >> In my opinion, what we should do, is to clarify what are the roles of
> >> SPARQL here and the relationship between SPARQL and SHACL.
> >
> > Why do I say that SPARQL/SPIN is inevitable for SHAQL?  There is no
> > other proposal that will satisfy the bulk of the members of the working
> > group.  I myself would prefer something based on OWL Constraints, but
> > there are many working group members who feel a need for features that
> > are not part of the RDF model theory.
> >
> >
> >> I think we should not throw in the towel now. In this email:
> >
> >>
> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2015Feb/0266.html
> >
> >>  You proposed a model-based semantics based on a simple language that
> >> can be used as a first step towards a core language. I was reviewing it
> >> and I think it is compatible with the axiomatic semantics of the same
> >> subset of language features.
>
> If this semantics is to be used as the, or even a, basis of SHACL, a
> significant portion of the working group would have to endorse it.  I
> haven't see any evidence that this is even a possibility.
>
> It is possible that OWL constraints, or the new model-theoretic semantics
> that I created, could become an ancillary part of SHACL.  OWL Constraints,
> in particular, is known to be compatible with a SPARQL-based semantics for
> SHACL.
>

In my opinion, the problem is the lack of an abstract syntax for what is
SHACL...if we keep talking about a specific technology that attaches SPARQL
queries to some execution mechanism, then we are not able to separate the
main parts of the language and we have to be tied up to SPARQL.

>
> >> It was said in another thread and during the meeting that most of the
> >> people behind Shape Expressions and Resource Shapes are part of the WG
> >> and I think we are all committed to define the new SHACL formalism. I
> >> still think that we should keep working on to find the common features
> >> that underlies all the proposals.
>
> I don't see any common ground emerging.  I don't even see any significant
> common ground between the various versions of Shape Expressions.
>

I would not call them "various versions" of shape expressions, from my
perspective, they are different design alternatives which can be used by
the WG.

At his moment I am working to unify my axiomatization with your proposed
semantics. Although it may need more work and I am not full time working on
this, you know that I am trying to adapt it following your comments.

Best regards, Jose Labra

>
> [...]
>
> peter
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-- 
-- Jose Labra