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Re: Wondering about an example of closed world validation

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Wed, 30 Jul 2014 10:18:26 -0700
Message-ID: <53D928E2.1030000@gmail.com>
To: Bernard Vatant <bernard.vatant@mondeca.com>, "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
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.

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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Received on Wednesday, 30 July 2014 17:18:57 UTC

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