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

From: Arthur Ryman <ryman@ca.ibm.com>
Date: Wed, 6 Aug 2014 08:30:04 -0400
To: Holger Knublauch <holger@topquadrant.com>
Cc: public-rdf-shapes@w3.org
Message-ID: <OFA4BD1852.36EBBDD3-ON85257D2C.0043F13F-85257D2C.0044AEA4@ca.ibm.com>
Holger,

Well put. Let me repeat the genesis of OSLC Shapes. Several years ago at 
OSLC we needed a way to express simple constraints. RDFS and OWL looked 
like what we needed but the semantics defined by W3C were in terms of 
inferring new triples, not checking constraints. We were aware of the OWL 
ICV semantics, but they were not submitted to W3C. So we defined OSLC 
Shapes. However, even if OWL ICV had been submitted to W3C, we'd still 
need a way to express more general constraints. That is where SPARQL comes 
in. 

Regards, 
___________________________________________________________________________
Arthur Ryman, PhD

Chief Data Officer, Rational
Chief Architect, Portfolio & Strategy Management
Distinguished Engineer | Master Inventor | Academy of Technology

Toronto Lab | +1-905-413-3077 (office) | +1-416-939-5063 (mobile)





From:   Holger Knublauch <holger@topquadrant.com>
To:     public-rdf-shapes@w3.org, 
Date:   08/03/2014 06:59 PM
Subject:        Re: Proposed change to the charter, section 4. 
Deliverables, Recommendation  Track



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 Wednesday, 6 August 2014 12:30:36 UTC

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