Re: Wondering about an example of closed world validation

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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>
>


-- 
Dimitris Kontokostas
Department of Computer Science, University of Leipzig
Research Group: http://aksw.org
Homepage:http://aksw.org/DimitrisKontokostas