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Re: Declaration consistency/RDF Parsing

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Mon, 15 Aug 2011 13:41:33 +0100
Cc: public-owl-comments@w3.org
Message-Id: <7C196DFD-A0D5-42ED-999E-C458285716D0@cs.man.ac.uk>
To: Alan Ruttenberg <alanruttenberg@gmail.com>
Alan,

I added this to the list of errata [1].

Thanks,
Ian

[1] http://www.w3.org/2007/OWL/wiki/Errata


On 25 Jul 2011, at 08:28, Alan Ruttenberg wrote:

> It may be worth clarifying the following:
> 
> http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Declaration_Consistency says:
> 
> An ontology O is said to have consistent declarations if each IRI I occurring in the axiom closure of O in position of an entity with a type T is declared in O as having type T. OWL 2 ontologies are not required to have consistent declarations: an ontology may be used even if its declarations are not consistent. 
> 
> However, in the RDF parsing spec, it seems we *do* need declaration consistency. 
> 
> For example:
> 
> _:x rdf:type owl:Restriction .
> _:x owl:onProperty y .
> _:x owl:hasSelf "true"^^xsd:boolean .
> { OPE(y) ≠ ε }	 ObjectHasSelf( OPE(y) )
> 
> Here we wouldn't say { OPE(y) ≠ ε } 
> If declaration consistency was optional we would only need DPE(y) = ε, APE(y) = ε
> 
> As it is now we have "At the end of this process, the graph G must be empty.". So if OPE(y) = ε these triples would not be parsed, we would end parsing the RDF with the "MUST" violated. That situation is potentially confusing [1] given "an ontology may be used even if its declarations are not consistent", although technically that statement would only apply to the *results* of the RDF parsing which are apparently always declaration consistent.
> 
> Perhaps a note either in Syntax 5.8.2 or somewhere in Mapping to RDF Graphs.
> 
> -Alan
> 
> [1] http://sourceforge.net/tracker/?func=detail&aid=3015732&group_id=90989&atid=595534
Received on Monday, 15 August 2011 12:42:09 GMT

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