Re: Wondering about an example of closed world validation

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
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>>> *
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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
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*Mondeca*
35 boulevard de Strasbourg 75010 Paris
www.mondeca.com
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