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Re: types of OWL

From: Yuzhong Qu <yzqu@seu.edu.cn>
Date: Sat, 3 Apr 2004 15:29:11 +0800
Message-ID: <007101c4194d$5c3ca130$fc0b77ca@xobjects>
To: "Dan Brickley" <danbri@w3.org>
Cc: <www-rdf-logic@w3.org>
As to the reasoning complexity, 

OWL DL has a difficult entailment problem, as inference in SHOIN(D) is of worst-case nondeterministic exponential time (NExpTime) complexity.

Inference in SHIF(D) is of worst-case deterministic exponential time (ExpTime) complexity, and OWL Lite has the same complexity.

Reference
[1] Ian Horrocks, Peter F. Patel-Schneider, and Frank van Harmelen. From SHIQ and RDF to OWL: The making of a web ontology language. Journal of Web Semantics, 1(1):7-26, 2003
[2] Stephan Tobies. Complexity Results and Practical Algorithms for Logics in Knowledge Representation. PhD thesis, LuFG Theoretical Computer Science, RWTHAachen,Germany, 2001.


Yuzhong Qu 

P.S. The complexity may be the most important element.

----- Original Message ----- 
From: "Dan Brickley" <danbri@w3.org>
To: "ror" <galvinr@tcd.ie>
Cc: <www-rdf-logic@w3.org>
Sent: Friday, April 02, 2004 8:59 PM
Subject: Re: types of OWL


> 
> * Dan Brickley <danbri@w3.org> [2004-04-02 07:53-0500]
> > 
> > * ror <galvinr@tcd.ie> [2004-04-02 13:16+0100]
> > > 
> > > Hello,
> > > 
> > > I've been trying to find the underlying differences between the different
> > > types of OWL languages i.e: OWL DL, OWL Lite and OWL full.
> > > 
> > > Are all of these languages forms of Description Logic? As far as I can gather
> > > OWL Lite is less expressive to suit users who want to incorporate semantics
> > > into their applications without the over complexity of OWL DL and full.
> > > 
> > > Does OWL lite use different forms of axioms than full or DL
> > > 
> > > If someone could set me straight on the differences I would be very grateful!
> > 
> > Here's a sketch.
> > 
> > "Full" is the full OWL language, an RDF-based language that extends RDFS with 
> > constructs useful for describing the terms used in Ontologies. "OWL DL"  
> > is a profile of that language created with special care to make it easy 
> > to work with in the Description Logic tradition. "OWL Lite" goes further in 
> > that direction, by ommiting some constructs known to be tough to work with
> > using DL techniques.
> 
> Re-reading your question, I guess you were looking for more details. I
> think the basic situation is that things from DL that aren't in Lite
> were taken out on the basis of their being known to be difficult to 
> implement. My understanding is that someone should be well on their way
> to implementing OWL Lite by studying the published DL literature, whereas
> complete reasoning with DL is more researchy...
> 
> Dan
> 
> 
> 
Received on Saturday, 3 April 2004 02:29:13 GMT

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