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Re: using Shape Expressions to validate RDF graphs

From: Karen Coyle <kcoyle@kcoyle.net>
Date: Fri, 11 Jul 2014 14:32:29 -0700
Message-ID: <53C057ED.4000407@kcoyle.net>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, Jose Emilio Labra Gayo <jelabra@gmail.com>
CC: "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>

On 7/11/14, 12:56 PM, Peter F. Patel-Schneider wrote:
> I'm still trying to figure out how shape expressions can constrain the
> shape of RDF graphs.  Yes, they can constrain the shape of a RDF graph
> flowing out of a single source, but that's only part of the problem.
> Another part, and one that I think is much more important, is
> constraining the "shape" of nodes that belong to a particular class.

Classes are orthogonal to shapes -- classes are semantic, shapes are 
syntactic. The Description Set Profile [1], which was an XML schema 
model for creating shapes with RDF, tried to address that (and I think 
it's worth looking at). That project was perhaps premature and never 
completed, but I am still convinced that the need to define the shape of 
our data exists. And shaping - as the DSP does - requires a big picture 
of your data. Much validation looks at individual "bits" but there is 
also a need to formulate and test large, complex structures, in addition 
to individual statements. If this capability does not exist in ShEx then 
we need to add it.

[1] http://dublincore.org/documents/dc-dsp/

> So, again, how can I describe those RDF graphs where every node that has
> an rdf:type link to :GraduateStudent has at least one :university triple
> and the object of such triples have an rdf:type link to
> :ResearchUniversity?
> peter
> On 07/11/2014 12:39 PM, Jose Emilio Labra Gayo wrote:
>> On Fri, Jul 11, 2014 at 7:02 PM, Karen Coyle <kcoyle@kcoyle.net
>> <mailto:kcoyle@kcoyle.net>> wrote:
>>     On 7/11/14, 9:31 AM, Jose Emilio Labra Gayo wrote:
>>         I mean, OWL and Shape Expressions have different goals...with
>> OWL you
>>         model an ontology of concepts, while with Shape Expressions
>> you just
>>         describe the shapes of RDF graphs.
>>     Jose, do you see them as complementary, perhaps working together?
>> In other
>>     words, is a solution needed that checks both OWL(-type) inferences
>> AND the
>>     shapes of the graphs? (I'm trying to get at the overall scope of
>> the need.)
>> Yes, definitely.
>> In my point of view, OWL is very good at semantic level while Shape
>> Expressions are more suited for the syntactic level or data
>> integration level.
>> Peter's example: "the spouse of every person is a person" seems for me
>> more at
>> the semantic or domain model level...and I would probably model it in
>> OWL.
>> In practice, if you have information like:
>> :john :spouse :mary .
>> and the previous declaration in OWL, the system could infer that :mary
>> is a
>> Person and if there were some declarations saying that mary is not a
>> person,
>> the system would detect an inconsistency.
>> Apart from that, if you have a data portal about people, you may be
>> interested
>> to say that a resource has the shape of a Person and has some
>> properties, like
>> ":spouse", "foaf:name", etc. In this case, you are describing the RDF
>> graph
>> that you are publishing or that someone can consume from your data
>> portal...
>> I think the motivations for declaring the Shape Expressions of a data
>> portal
>> are very pragmatic and I have found that they cover a need for RDF data
>> publication, consumption and integration...but of course, they are
>> complementary with having OWL ontologies.
>> Best regards, Jose Labra
>>     kc
>>     --
>>     Karen Coyle
>>     kcoyle@kcoyle.net <mailto:kcoyle@kcoyle.net> http://kcoyle.net
>>     m: 1-510-435-8234 <tel:1-510-435-8234>
>>     skype: kcoylenet
>> --
>> Saludos, Labra

Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet
Received on Friday, 11 July 2014 21:32:59 UTC

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