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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...


> 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 UTC

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