W3C home > Mailing lists > Public > public-owl-wg@w3.org > March 2008

Distinguishing fragments

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Fri, 7 Mar 2008 17:30:15 +0000
Message-Id: <387E6274-C533-4C0E-AD00-71F96B6BB874@comlab.ox.ac.uk>
To: Web Ontology Language ((OWL)) Working Group WG <public-owl-wg@w3.org>

We wanted to move a discussion on distinguishing fragments to the  
list. Let me start by summarising what has been said so far (I used  
my best endeavours, but others may want to add corrections/ 
clarifications):

Jim: why do we need a DL version of OWL-R? Couldn't it be confusing  
with DL-Lite?

Boris: OWL-R allows for moving between RDF and DL worlds -- may be  
important to some.

Jim: people I talked to said they would only use DL-Lite xor OWL-R

Achille: Agrees that there is potential for confusion especially due  
to fragment names; OWL-R DL covers datalog reasoning and colleagues  
in China have a need for it.

Boris: suggests OWL-T (taxonomic), OWL-R and OWL DB for EL++, DLP/ 
rules and DL-Lite fragments.

Jim: we would end up with the following naming scheme:

OWL Full and OWL DL
(OWL lite) - we hope to deprecate
OWL-T DL
OWL-T Full
OWL-DB DL
OWL-DB Full
OWL-R DL
OWL-R Full

How would a user choose between OWL DB DL and OWL R DL? Thinks that  
OWL-R and OWL-DB are both motivated by large scale data rich  
applications, so would have a problem with the name OWL-DB for one  
and not the other. Suggests OWL Datatlog and OWL Rules, but overlap  
issue more important than names.

Zhe: OWL-DB is confusing; Oracle has no short term plan to support;  
suggests OWL-A (A for Abox) or OWL-I (I for instances) instead of OWL- 
DB. Thinks OWL-R DL might be useful as a restricted version of OWL-R  
Full.

Jim: RDF triple store folks said they were confused about when to use  
DL-Lite and when to use OWL-R DL. Suggest that it may be OK to have  
asymmetric fragments (not always both Full and DL versions).

Boris: OWL-R Full is for RDF users wanting more expressive power; OWL- 
R DL is for OWL 1.1 DL users wanting to down-size. Nice thing is that  
both communities can meet at the same level.

Ian: Don't need symmetric fragments -- omit those with no clear  
rationale (such as OWL-DB Full). Choosing between OWL-DB and OWL-R  
should be easy: if you can live within the restrictions imposed by  
OWL-DB and/or want to use data directly from relational DBs, then use  
OWL-DB; otherwise, use OWL-R. Agrees that design issues more  
important than naming.

Ian: Can appeal to large community when they realise that they can  
use OWL-DB with existing relational DBs. This isn't to detract from  
OWL-R. Agrees with Achille that OWL-R DL can be be useful for LP  
implementers.

Ian: Need better names and a clear rationale (in fragments intro).  
Case for "OWL-DB" is a no-brainer -- can use OWL directly with data  
that is already sitting in relational DBs.

Jim: asymmetry favours DL over Full?

Jim: but why would we recommend to such users that they use OWL R DL  
instead of DL-Lite?  Also if this is true of OWL R DL, why not DL- 
Lite Full? Shall we move discussion to list?

Ian: asymmetry means only including fragments for which there is  
clear rationale.

Ian: If users can't live within the restrictions imposed by DL-Lite  
(it is quite a restricted language), then they should use OWL-R. Yes,  
let's move to list.
Received on Friday, 7 March 2008 17:30:33 GMT

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