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Re: Profiles intro

From: Ivan Herman <ivan@w3.org>
Date: Wed, 09 Apr 2008 12:52:45 +0200
Message-ID: <47FC9FFD.9000008@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>


Carsten Lutz wrote:
> 
> I have added three slogans to the intro, trying to be careful about
> not being controversial. Put on your flamethrowers. :)

And you should call the fire brigade:-)

More seriously:

[[[
- "The EL++ profile is for efficient reasoning about large-scale 
ontologies formulated on a high level of abstraction."
]]]

To be honest, I do not understand that. I am not playing dumm; I 
_really_ do not understand what you mean!

[[[
- "The DL-Lite profile is for using conventional database systems to 
efficiently query large amounts of data in the presence of a very 
lightweight ontology."
- "The OWL-R profile is for efficient rule-based reasoning about 
lightweight ontologies and potentially large amounts of data."
]]]

The interesting thing is that, from a user point of view and based on 
those two statements, there is no clear reason why choosing one over the 
other! Both profiles are for lightweight ontologies and large amount of 
data.... _That_ statement I do understand and like. But then... why 
having _both_ DL-Lite and OWL-R?

Is there a way to differentiate between the terms 'lightweight' 
ontologies? Can we say that OWL-R is 'lighter' than DL-Lite?

To be more positive:-), I guess _a_ differentiating factor is the 
technology that can be used to implement those. Rule based means that I 
can implement OWL-R via either some simple (Horn?) rule engine or a 
simple procedural environment easily. I am not sure how one can 
characterize the DL-Lite implementation engine.

Carsten, I do not try to play hard ball here. I really believe that 
these questions should be answered adequately... and we would gain by 
fleshing this out...

Ivan



> 
> greetings,
>         Carsten
> 
> On Wed, 9 Apr 2008, Ivan Herman wrote:
>>
>> Carsten,
>>
>> and I understand very well that these things are complicated... And 
>> the error I made on my example just shows how difficult that is:-(
>>
>> However... eventually we do need a kind of an 'elevator pitch', ie, a 
>> short, clear, and not-too-detailed argument for end-users when and why 
>> they would use one profile over the other.
>>
>> In some ways, we had that for  OWL-Full and DL: I know, it can be 
>> discussed at nauseam, it is not precise, and tastes differ a lot, but 
>> I remembered Dan Brickley saying something like:
>>
>>     - Some application just need to express and interchange terms 
>> (with possible scruffiness): OWL Full is fine
>>     - Some applications need rigor and complex term classification 
>> with a guarantee offered by reasoning procedures; then OWL DL/Lite 
>> might be the good choice
>>
>> which is good enough for the lambda SW application developer.
>>
>> Let us try to agree upon some of these...
>>
>> Ivan
>>
>> Carsten Lutz wrote:
>>> On Wed, 9 Apr 2008, Ivan Herman wrote:
>>>>
>>>> Bijan Parsia wrote:
>>>>>
>>>>> It is really nice (as far as I'm concerned), but I think we can 
>>>>> anticipate some negative comment about the emphasis on the 
>>>>> "tractability" POV (e.g., from Jim Hendler). And, after all, 
>>>>> computational efficiency is a necessary, not sufficient, condition 
>>>>> for inclusion. 
>>>>
>>>> +1. No, +100...:-)
>>>>
>>>> What I am looking for are statements that make it clear in which 
>>>> circumstances I would choose one profile over the other (even if I 
>>>> have no idea of the implementation details, nor do I want to deal 
>>>> with those). The fact that it can be implemented in polynomial time 
>>>> or whatever is only one (albeit important) aspect.
>>>
>>> I agree and certainly don't consider the intro finished. The purpose
>>> of my changes was only to have an intro that can be published at the
>>> end of this week, and I think the current one can. (the action on me
>>> was to put the explanations of the three fragments that I had in my
>>> OWLED slides, and I did even more than that).
>>>
>>> An issue with the other aspects of fragments is that they are difficult
>>> to formulate without raising controversy. Let's take your example:
>>>
>>>> I have heard arguments that say "if your ontology has a simple 
>>>> structure, but have a large abox, then use DL-Lite";
>>>
>>> I am not totally happy with this formulation, and I guess Zhe is even
>>> less so:
>>>
>>> - I am uncomfortable with the "ontology has a simple structure part",
>>>   because EL++ is also targeted at ontologies of a simple structure and
>>>   can also handle ABoxes, whereas I conceive DL-Lite as a constraint
>>>   language rather than an ontology language.
>>>
>>> - I suppose Zhe won't like the "large ABox" part, because ontologies
>>>   with a simple structure and large data is precisely what OWL-R is
>>>   also made for.
>>>
>>> My aim here is not to discuss these issues, but only to point out that
>>> it may by hard to find general rules of the kind that you imagine.
>>>
>>>> I could imagine that a more detailed argumentation should (probably 
>>>> must...) be given in more details in the primer, but some of these 
>>>> should be added, I believe, in the profile document, too.
>>>
>>> I agree, but we have to be careful.
>>>
>>> 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
>>
> 
> -- 
> *      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 Wednesday, 9 April 2008 10:53:19 GMT

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