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"A" vs. "the"

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Thu, 22 Jan 2009 16:18:42 +0000
Message-Id: <6FA5C38D-03BB-4E75-89D0-50577A486EE6@cs.man.ac.uk>
To: W3C OWL Working Group <public-owl-wg@w3.org>

http://www.w3.org/2007/OWL/wiki/index.php? 
title=New_Features_and_Rationale&diff=17359&oldid=prev

It's not sufficient to make the following change:

"""''OWL 2 QL''' is a maximal language for which reasoning, including  
query answering, is known to be worst case logspace (same as DB)."""

OWL 2 QL is not maximal (as I recall). As I said in my email. Also,  
in the profiles document:

"""The OWL 2 QL profile admits sound and complete reasoning in  
LOGSPACE with respect to the size of the data (assertions), while  
providing many of the main features necessary to express conceptual  
models such as UML class diagrams and ER diagrams. In particular,  
this profile contains the intersection of RDFS and OWL 2. It is based  
on the DL-Lite family of description logics. Several variants of DL- 
Lite have been described in the literature [DL-Lite], and DL-LiteR  
provides the logical underpinning for OWL 2 QL. DL-LiteR does not  
require the unique name assumption (UNA), since making this  
assumption would have no impact on the semantic consequences of a DL- 
LiteR ontology. More expressive variants of DL-Lite, such as DL- 
LiteA, extend DL-LiteR with functional properties, """"

*More expressive*.

""""and these can also be extended with keys; however, for query  
answering to remain in LOGSPACE, these extensions require UNA and  
need to impose certain global restrictions on the interaction between  
properties used in different types of axiom. Basing OWL 2 QL on DL- 
LiteR avoids practical problems involved in the explicit  
axiomatization of UNA. Other variants of DL-Lite can also be  
supported on top of OWL 2 QL, but may require additional restrictions  
on the structure of ontologies [DL-Lite].""""

Cheers,
Bijan.
Received on Thursday, 22 January 2009 16:15:18 GMT

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