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[LC response] To Jeff Heflin

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Fri, 7 Aug 2009 14:20:37 +0100
Message-Id: <0459D71B-1476-4DE8-AB5D-4FB822C84F28@comlab.ox.ac.uk>
Cc: public-owl-comments@w3.org
To: Jeff Heflin <heflin@cse.lehigh.edu>
Dear Jeff,

Thank you for your comment
      <http://lists.w3.org/Archives/Public/public-owl-comments/ 
2009Jul/0014.html>
on the OWL 2 Web Ontology Language last call drafts.

Regarding imports, as you can see from [1] the direct semantics of  
OWL 2 ontologies is explicitly applied to the axiom closure (with at  
link back to the definition of axiom closure in Syntax [2]).

Regarding deprecation, we introduced owl:deprecated mainly for  
backward compatibility in order to capture the deprecated classes of  
OWL 1. Thus, the capabilities of OWL 2 regarding deprecation are  
essentially the same as those of OWL 1.

Regarding profiles, the current design is the result of long and  
careful analysis both within and without the working group. It is  
true that a consistency check is typically required as part of query  
answering, but this is true even if the language includes only  
disjointness, which is a basic feature of conceptual modelling  
languages; moreover, consistency checking is relatively easy in the  
profiles (see [2]), and only needs to be performed once for a given  
ontology. The QL profile has been designed so that query answering  
has the same complexity as for relational databases, so there is no  
reason why QL systems should not be just as scalable as relational  
database systems; tests show that existing implementations can easily  
deal with data in the order of millions of triples.

Regarding arithmetic operations, the working group has specified an  
extension that allows for linear (in)equations with rational  
coefficients; this was not made part of the basic specification as it  
would place a heavy burden on implementers.

[1] http://www.w3.org/2007/OWL/wiki/Direct_Semantics#Ontologies
[2] http://www.w3.org/2007/OWL/wiki/Profiles#Computational_Properties

Please acknowledge receipt of this email to <mailto:public-owl- 
comments@w3.org> (replying to this email should suffice). In your  
acknowledgment please let us know whether or not you are satisfied  
with the working group's response to your comment.

Regards,
Ian Horrocks
on behalf of the W3C OWL Working Group
Received on Friday, 7 August 2009 13:21:27 GMT

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