Re: [Bigdata-developers] OWL Inference

[Mike P. <mi...@sy...>]

Jurgen,

I just wanted to let you know that while I have not gotten to the bottom of the problem yet, I agree with you that there is indeed a problem.  OWLIM's answer looks more correct to me than does our answer.  I don't understand why we are seeing (narrower, TechnoPop) and (narrower, ElectroPop) since narrower is not itself a transitive property.  I think the fact that we are not seeing (semanticRelation, TechnoPop) and (semanticRelation, ElectroPop) might have to do with our FastClosure inference program.  I suspect that using the FullClosure program might solve the latter problem.  I would be surprised if it solved the former too, but it is possible.  Maybe give it a shot.  (See AbstractTripleStore.Options.CLOSURE_CLASS for details.)

Long story short, yes I think there is a bug.  :)

I will log an issue for it in our bug tracker system.

If you are able to uncover the source of the problem please let me know!

Thanks,
Mike


-----Original Message-----
From: Jürgen Jakobitsch [mailto:jak...@pu...] 
Sent: Wednesday, April 28, 2010 1:52 AM
To: big...@li...
Subject: [Bigdata-developers] OWL Inference

hi, first of all congrats to this great project,
i checked it out once a couple of months ago and 
i can see that there some significant improvements.

however might have found a bug in the inference engine,
that can be reproduced like so :

1. instantiate a bigdata sail with fullfeatured properties
2. add http://www.w3.org/2009/08/skos-reference/skos-owl1-dl.rdf with baseURL http://www.w3.org/2004/02/skos/core
3. add http://turnguard.com/virtuoso/test10.rdf

now do the following sparql query

SELECT *
WHERE {
<http://www.turnguard.com/Music> ?p ?o
}

the result from bigdata looks like this

http://www.w3.org/1999/02/22-rdf-syntax-ns#type  	http://www.w3.org/2004/02/skos/core#Concept
http://www.w3.org/2000/01/rdf-schema#label 	        "Music"@en
http://www.w3.org/2004/02/skos/core#narrower 	        http://www.turnguard.com/ElectroPop
http://www.w3.org/2004/02/skos/core#narrower 	        http://www.turnguard.com/Pop
http://www.w3.org/2004/02/skos/core#narrower 	        http://www.turnguard.com/TechnoPop
http://www.w3.org/2004/02/skos/core#narrowerTransitive 	http://www.turnguard.com/ElectroPop
http://www.w3.org/2004/02/skos/core#narrowerTransitive 	http://www.turnguard.com/Pop
http://www.w3.org/2004/02/skos/core#narrowerTransitive 	http://www.turnguard.com/TechnoPop
http://www.w3.org/2004/02/skos/core#prefLabel 	        "Music"@en
http://www.w3.org/2004/02/skos/core#semanticRelation 	http://www.turnguard.com/Pop
http://www.w3.org/1999/02/22-rdf-syntax-ns#type 	http://www.w3.org/2000/01/rdf-schema#Resource


the result from owlim (swiftowlim beta 12) like this

http://www.w3.org/2004/02/skos/core#narrowerTransitive  http://www.turnguard.com/ElectroPop
http://www.w3.org/2004/02/skos/core#narrowerTransitive 	http://www.turnguard.com/TechnoPop
http://www.w3.org/2004/02/skos/core#narrowerTransitive 	http://www.turnguard.com/Pop
http://www.w3.org/1999/02/22-rdf-syntax-ns#type 	http://www.w3.org/2004/02/skos/core#Concept
http://www.w3.org/1999/02/22-rdf-syntax-ns#type 	_:node1
http://www.w3.org/2004/02/skos/core#semanticRelation 	http://www.turnguard.com/ElectroPop
http://www.w3.org/2004/02/skos/core#semanticRelation 	http://www.turnguard.com/TechnoPop
http://www.w3.org/2004/02/skos/core#semanticRelation 	http://www.turnguard.com/Pop
http://www.w3.org/2004/02/skos/core#prefLabel 	        "Music"@en
http://www.w3.org/2000/01/rdf-schema#label 	        "Music"@en
http://www.w3.org/2004/02/skos/core#narrower 	        http://www.turnguard.com/Pop

note that i'm positivly surprised by the inferred rdf-schema#Resource with bigdata
but there are significant differences between the two inference engines, where owlim
seems to be right in most cases.

please note that :

in skos : narrower is a subProp of narrowerTransitive (same for broader), both are inverse,
the transitives are subProps of semanticRelation, so the construct is a bit complex.

any suggestions if i'm doing some wrong or this is a bug really welcome.

wkr www.turnguard.com/turnguard

-- 
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