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Re: Proposed change to the charter, section 4. Deliverables, Recommendation Track

From: John Walker <john.walker@semaku.com>
Date: Thu, 7 Aug 2014 07:50:32 +0300
Message-Id: <E452B10A-D21F-4CBE-B72E-18AEB33C1FFE@semaku.com>
Cc: Holger Knublauch <holger@topquadrant.com>, "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
Hi Peter,

I think RDF datasets as defined in RDF 1.1 [1] cannot be ignored.

Seeing as formats like JSON-LD and TriG support quads, it seems sensible to be able to somehow validate these.

I can understand this could be a challenge given there are no formal semantics for RDF datasets defined yet [2]. On the other hand it could be as simple as thinking of a dataset as a collection of independent graphs which can each be validated separately (given a mechanism to associate the right 'template' to a named (or the default) graph).

Or they could be explicitly put out of scope.

Either way RDF datasets should not be ignored.

[1] http://www.w3.org/TR/rdf11-concepts/#section-dataset
[2] http://www.w3.org/TR/rdf11-datasets/

Regards,

John

On 7 Aug 2014, at 01:44, "Peter F. Patel-Schneider" <pfpschneider@gmail.com> wrote:

> Well, I did present what I thought was a good neutral set of deliverables, namely
> 
> 1. A syntax and semantics for shapes specifying how to construct shape
> expressions and how shape expressions are evaluated against RDF graphs.
> 
> 2. An RDF vocabulary for expressing these shapes in RDF triples, so they can
> be stored, queried, analyzed, and manipulated with normal RDF tools.
> 
> 3. OPTIONAL A specification of how shape verification interacts with
> inference.
> 
> 4. OPTIONAL A compact, human-readable syntax for expressing shapes.
> 
> peter
> 
> 
> 
> On 08/03/2014 03:57 PM, Holger Knublauch wrote:
>> Hi Peter,
>> 
>> this mailing list provides plenty of evidence that OWL is not expressive
>> enough and something on the level of SPARQL is needed. ShEx has an escape
>> mechanism to fall back to SPARQL [1], and IBM has explicitly stated that this
>> is required too [2]. OWL cannot even do basic math or string operations,
>> neither does it have a concept of "variables" that is very much needed to do
>> complex joins. So as a minimum, the outcome of this group should be to agree
>> on a high-level vocabulary (possibly OWL and/or Shapes) plus a mechanism to
>> represent other cases with something like SPARQL. Do you agree so far?
>> 
>> Yes, OWL does have a very large overlap with the Shapes that were originally
>> submitted (mainly cardinalities and ranges). So it is a valid question whether
>> both are needed. But if you look at the SPIN specification you may notice that
>> once you have a mechanism such as SPIN (with templates) in place, it becomes
>> quite trivial to add any number of libraries including the "Shapes"
>> implementation that I presented a while ago [3]. And this library can cover
>> many more use cases than either the current Shapes proposals nor OWL closed
>> world can represent, see for example [4] and [5]. Could you clarify whether
>> your goal is to prevent "Shapes" becoming a standard and use OWL instead?
>> 
>> I believe it is easy to just say no to everything. Have you worked out a
>> better proposal? How should the charter look like from your point of view?
>> 
>> Thanks
>> Holger
>> 
>> 
>> [1] http://www.w3.org/Submission/shex-primer/#semact
>> [2] http://lists.w3.org/Archives/Public/public-rdf-shapes/2014Jul/0246.html
>> [3] http://lists.w3.org/Archives/Public/public-rdf-shapes/2014Jul/0237.html
>> [4] http://semwebquality.org/mediawiki/index.php?title=SemWebQuality.org
>> [5] http://lists.w3.org/Archives/Public/public-rdf-shapes/2014Aug/0040.html
>> 
>> 
>> On 8/4/2014 3:33, Peter F. Patel-Schneider wrote:
>>> I do not support this approach at this time.  To me it looks too much like
>>> having two standards for the same thing.  I feel that the SPARQL-based
>>> approach and the model-checking approach (which is what OWL+CWA boils down
>>> to for RDF graphs) have quite a large overlap in their capabilities, even
>>> though they may look quite different technically.
>>> 
>>> It may be that I am wrong in this, of course, and that there are good
>>> reasons to split in this way.
>>> 
>>> 
>>> peter
>>> 
>>> 
>>> On 08/02/2014 11:21 PM, Holger Knublauch wrote:
>>>> A pragmatic proposal: I do believe there is consensus that this WG can
>>>> potentially create some useful and relevant output that could lead to broader
>>>> use cases for semantic web technology as a whole. There are several proposals
>>>> on the table that are potentially complementary to each other. Assuming there
>>>> are enough people who actually sign up for the work, why not produce multiple
>>>> deliverables that cover more use cases?
>>>> 
>>>> 1) Shapes + SPIN, with an explicit mandate to have semantics that are
>>>> executable by SPARQL engines, from day one. The alternative would be ShEx and
>>>> this could be figured out in the beginning of the WG. This deliverable would
>>>> be like an extension to SPARQL.
>>>> 
>>>> plus
>>>> 
>>>> 2) OWL closed world semantics, so that existing OWL ontologies can be reused.
>>>> This deliverable would basically be an "appendix" to the OWL 2 spec.
>>>> 
>>>> This would allow the interest groups to stay on their home turf without
>>>> blocking each other, because blocking each other would be the worst outcome of
>>>> all. I see no technical difficulties with such as stack, because these
>>>> technologies are complementary to each other: we use OWL closed world + SPIN
>>>> all the time, and it works well in practice. In fact I believe both
>>>> specifications have a good and stable starting point so that we could proceed
>>>> with the process very swiftly.
>>>> 
>>>> Peter, would this be an acceptable direction for you?
>>>> 
>>>> Thanks,
>>>> Holger
>>>> 
>> 
>> 
> 
Received on Thursday, 7 August 2014 04:51:05 UTC

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