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Re: Wondering about an example of closed world validation

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Thu, 31 Jul 2014 16:18:00 +0200
Message-ID: <CAK4ZFVGZ6pyr42Jv3r29d2S7fyx0rLtjn-sepzcepEQhJ96ANw@mail.gmail.com>
To: Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>
Cc: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
Hi Dimitris

The RDFS inference will not necessarily hide the inconsistency in your
example. It will point to it instead, if your ontology formally forbids a
Country to be a Person by some class disjunction. If it's not forbidden, so
be it. Switzerland will be a Person.
But I suppose your point is that a closed world validation would check
first the declared class of the dbo:spouse object, and if it finds Country
instead of Person, it will declare this triple invalid, right?




2014-07-31 8:08 GMT+02:00 Dimitris Kontokostas <
kontokostas@informatik.uni-leipzig.de>:

>
>
>
> On Wed, Jul 30, 2014 at 8:18 PM, Peter F. Patel-Schneider <
> pfpschneider@gmail.com> wrote:
>
>> Indeed.  (Well, except that just using FOAF vocabulary might not be
>> enough to bring in FOAF axioms.  Explicit importing - oops, that's not in
>> RDF yet - is probably a better trigger here.)
>>
>> I think that RDF validation should be done against the closure of an RDF
>> graph.  I proposed this earlier in
>> http://lists.w3.org/Archives/Public/public-rdf-shapes/2014Jul/0189.html
>> as an option, but I strongly believe that validating against the RDFS
>> closure should be the norm.
>>
>
> Maybe I am biased towards my experience with DBpedia and messy data but I
> would vote against this being the norm.
> take http://dbpedia.org/resource/Harry_Froboess for example and look at
> the dbo:spouse property (dbr:Switzerland, dbr:Berlin)
> This is of course an error in DBpedia but applying rdfs inference would
> hide it and make Switzerland & Berlin Persons.
>
> Dimitris
>
>
>>
>> peter
>>
>>
>>
>>
>> On 07/30/2014 10:01 AM, Bernard Vatant wrote:
>>
>>> Hello all
>>>
>>> This is an example to illustrate a question this group should IMHO
>>> clarify.
>>>
>>> Suppose I have this (closed world) validation rule (in natural language)
>>> R1 "A value of dcterms:creator must be an instance of foaf:Agent"
>>>
>>> Now I have this graph
>>>
>>> G = { :x   dcterms:creator [foaf:familyName  "Smith"] }
>>>
>>> In a closed world logic, G is not valid against R1, because the value of
>>> dcterms:creator is not explicitly declared as a foaf:Agent
>>>
>>> But one could argue that since both data and R1 use elements in the FOAF
>>> namespace, they both abide by FOAF semantics, which includes
>>>
>>> A1 : foaf:familyName  rdfs:domain foaf:Person
>>> A2 : foaf:Person rdfs:subClassOf  foaf:Agent
>>>
>>> Hence [foaf:familyName "Smith"] is indeed a foaf:Agent, and G is valid
>>> modulo
>>> FOAF semantics.
>>>
>>> This issue is already known in SPARQL, which can be run against the same
>>> data
>>> with or w/o e.g., RDFS inference with different results.
>>>
>>> The bottom line is that RDF uses URIs. Classes and predicates URIs have
>>> semantics which are not necessarily explicited in the local graph/data,
>>> but
>>> that one can (should?) find out using the Web infrastructure and open
>>> world
>>> inferences.
>>>
>>> Note that A1 and A2 could be, or not, duplicated in the local graph, and
>>> the
>>> inference before validation could be limited to the local graph or
>>> extended to
>>> the Web, there again with different results.
>>>
>>> Thoughts?
>>>
>>> --
>>> *Bernard Vatant
>>>
>>> *
>>> Vocabularies & Data Engineering
>>> Tel : + 33 (0)9 71 48 84 59
>>> Skype : bernard.vatant
>>> http://google.com/+BernardVatant
>>> --------------------------------------------------------
>>> *Mondeca*****
>>> 35 boulevard de Strasbourg 75010 Paris*
>>> *
>>> www.mondeca.com <http://www.mondeca.com/>
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>>> >
>>> ----------------------------------------------------------
>>>
>>
>>
>
>
> --
> Dimitris Kontokostas
> Department of Computer Science, University of Leipzig
> Research Group: http://aksw.org
> Homepage:http://aksw.org/DimitrisKontokostas
>



-- 

*Bernard Vatant*
Vocabularies & Data Engineering
Tel :  + 33 (0)9 71 48 84 59
Skype : bernard.vatant
http://google.com/+BernardVatant
--------------------------------------------------------
*Mondeca*
35 boulevard de Strasbourg 75010 Paris
www.mondeca.com
Follow us on Twitter : @mondecanews <http://twitter.com/#%21/mondecanews>
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Received on Thursday, 31 July 2014 14:18:50 UTC

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