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Re: Test cases and examples for dataset entailment

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Tue, 11 Sep 2012 14:11:21 +0200
Message-ID: <504F2A69.7000401@emse.fr>
To: Richard Cyganiak <richard@cyganiak.de>
CC: RDF Working Group WG <public-rdf-wg@w3.org>
DD0. If there is no semantics, then there is no notion of equivalence.
In any case, however surprising it may be:

{ :s :p 42 }

is not equivalent and does not even entail:

{ :s :p +42 }

in any entailment regime that I know of (I don't know RIF).
The reason is because 42 in the first dataset is the literal 
"42"^^xsd:integer and +42 in the second dataset is "+42"^^xsd:integer. 
These are two different literals, therefore are two different names, so 
the vocabularies of the second dataset is not included in the vocabulary 
of the first one, so there cannot be entailment, even with D-entailment, 
even with OWL Full entailment, and not with OWL DL entailment because 
the triple alone does not form a valid OWL DL ontology.

I raised an issue about this particularity of the RDF 1.0 semantics:

ISSUE-84: "Bug" in D-entailment with literals in non-canonical form



DD1. You say:

"""Under OWL dataset semantics:

  {}
  :g1 { :o1 owl:differentFrom :o1 }

is a contradiction."""

No, it's OWL-dataset-consistent, but it entails:

  :g1 { G }

for any RDF graph G.


DD3.  We can mention the SPARQL 1.1 Service description vocabulary, and 
give an example using it:

<>  a  sd:Dataset;
     sd:defaultEntailmentRegime  er:rdf
     sd:namedGraph  [
        a  sd:NamedGraph;
        sd:name  "http://example.com/g"^^xsd:anyURI;
        sd:entailmentRegime  er:simple
     ]


This does not work perfectly since sd:defaultEntailmentRegime normally 
apply to a sd:Service rather than a sd:Dataset. Yet, it is not formally 
said that sd:Dataset is disjoint with sd:Service.


DD4 to DD7: alright.



--AZ

Le 11/09/2012 11:46, Richard Cyganiak a écrit :
> On 10 Sep 2012, at 17:30, Richard Cyganiak wrote:
>> Two other things that I'd quite like to see before we can call the proposal complete:
>>
>> 1. Some thinking on how it addresses our graph use cases. (Do we have an “official” list of those? I've lost track with all the various documents.)
>>
>> 2. Some examples for semantic extensions, in order to show that various other proposed semantics can actually be done as proper semantic extensions of this minimal dataset semantics.
>
> I've worked a bit on this item and made attempts to formalize three semantic extensions:
>
> * owl:imports (formally explains how owl:imports works in RDF datasets)
> * web datasets (formally defines that stuff published on the web is asserted)
> * direct graph semantics (permits "literal" immutable graphs)
>
> http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs/Minimal-dataset-semantics#Possible_Semantic_Extensions
>
> I'm not proposing that we should standardize any of this; the intention is merely to explore how flexible/extensible the semantics proposed on that page is.
>
> Again, I'm not really good at this formal semantics stuff, so this might all be spectacularly wrong.
>
> Best,
> Richard
>


-- 
Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
France
Tél:+33(0)4 77 42 83 36
Fax:+33(0)4 77 42 66 66
http://zimmer.aprilfoolsreview.com/
Received on Tuesday, 11 September 2012 12:12:20 GMT

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