- From: Ian Horrocks <horrocks@cs.man.ac.uk>
- Date: Mon, 15 Aug 2011 13:41:33 +0100
- To: Alan Ruttenberg <alanruttenberg@gmail.com>
- Cc: public-owl-comments@w3.org
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 UTC