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Re: Profiles intro

From: Ivan Herman <ivan@w3.org>
Date: Thu, 10 Apr 2008 13:36:09 +0200
Message-ID: <47FDFBA9.4050207@w3.org>
To: Carsten Lutz <clu@tcs.inf.tu-dresden.de>
CC: Bijan Parsia <bparsia@cs.man.ac.uk>, OWL Working Group WG <public-owl-wg@w3.org>
Hi Carsten,

Carsten Lutz wrote:
> Hi Ivan,
> 
> here are some responses to your text, of course representing only my
> own view of things.
> 
> [...]
>> [[[
>> In some cases, the emphasis is on possibly very large concept 
>> hierarchies and the corresponding queries, rather than on 
>> sophisticated characterizations of, and with properties (roles). EL++ 
>> is a profile where such queries can be responded in polynomial time.
> 
> Hmm. The term "concept hierarchies" sounds too weak for what you can
> do with EL++. Indeed, you *can* relate classes in terms of properties
> in EL++ (also in OWL-R, only not in DL Lite). EL++ is a true ontology
> language and can do much more than describing hierarchies. For
> example, it *does* have sophisticated facilities for talking about
> roles.
> 

I am trying to find what the _emphasis_ is, and not to be exhaustive! 
That is why I used the word 'emphasis'. What would you put in place instead?

> Also the term "queries" seems misleading here since it sound
> like querying of data. I would rather speak of classification and
> similar services that are central for ontologies.
> 

Yes, that is what meant; would 'ontology query' work? I am not sure what 
the terminology you guys use...

>> In other cases, the emphasis is to provide a minimal classification 
>> and federation vocabulary over a possibly very large set of data 
>> (typically in the form of RDF triplets), while maintaining efficient 
>> querying. Two such
> 
> DL Lite seems unrelated to RDF triplets. It is only OWL-R that is very
> RDF-ish.
> 

Ouch. That hurts. This is a Semantic Web ontology, so if an ontology is 
unrelated to RDF triplets, than what does it have to do with this group? 
I do not see why OWL-R would be more RDF-ish than DL Lite or vice versa.

We are talking about data and, possibly, lots of it. Those are typically 
  RDF or RDF-able on the Semantic Web. That DL-Lite may be of interest 
outside of the Semantic Web may be true, but is besides the point in 
this environment...

>> profiles are defined: DL-Lite, that can be implemented on top of 
>> traditional database systems using query rewriting, and OWL-R, that 
>> can be implemented using basic rule systems.
>> ]]]
> 
> True.
> 
>> I hope this is at least factually correct. It is interesting to note 
>> that on such high level there is no real difference between DL-Lite 
>> and OWL-R, and the only way to differentiate them on that level is how 
>> they are implemented. 
> Yes, a main difference between DL-Lite and OWL-R is implementation
> techniques. Another one is maybe RDF-ishness.
> 

where I strongly disagree.

> [...]
>> I also believe that the names of the profiles should somehow reflect 
>> the high level characterization. Something like:
>>
>> EL++     -> OWL HI (for hierarchies?)
> 
> I would be very unhappy with this. As noted above, this sounds very weak
> given what EL++ can actually do.
> 

Yeah, I was not very sure about that. But what else?

>> DL Lite  -> OWL DB
> 
> Sounds reasonable. But is Zhe happy with this? One of the main reasons
> d'etre for OWL-R seem to be the implementation in DBs with rules.
> 

But, well, OWL DB can be implemented without rules, right? So it is, in 
some sense, more closely bound to databases than OWL-R.

Of course it is up to Zhe to tell me the details but my feeling is that 
what they do is to use a _separate_ rule engine that Oracle happens to 
have. It would actually be interesting to know whether Oracle would be 
interested in implementing DL Lite or not...

>> OWL-R    -> OWL Rules
> 
> There is a chance of misinterpretation here.  Namely, there is a lot
> of work on combining OWL with rule-based formalisms (aren't some of
> them even called "OWL Rules"?), and this is very different from
> *implementing* an OWL profile using rules. In general, are these
> names reflecting the typical use of a profile or a technique supported
> by the profile? Not so clear to me.
> 

That I do not know... Maybe somebody else on the list does

> In general, the naming issue is very difficult. I am not sure whether
> it is a good idea to reflect the use of the fragments in their name,
> as this is very suggestive and may be misleading (and people may find
> interesting uses for the profiles that we never thought of).
> 

On the other hand, we need names that are suggestive and helpful to 
people. Having said that, 'OWL DL' is a meaningless name for those who 
do not know what description logic is...

Ivan

> greetings,
>         Carsten
> 
> 
> -- 
> *      Carsten Lutz, Institut f"ur Theoretische Informatik, TU 
> Dresden       *
> *     Office phone:++49 351 46339171   
> mailto:lutz@tcs.inf.tu-dresden.de     *

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf


Received on Thursday, 10 April 2008 11:37:12 GMT

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