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Re: ISSUE-125 (min1some): Min 1 QCR = someValuesFrom - Serialize as someValuesFrom?

From: Rinke Hoekstra <hoekstra@uva.nl>
Date: Wed, 21 May 2008 09:12:21 +0200
Cc: "OWL Working Group WG" <public-owl-wg@w3.org>
Message-Id: <30F72063-97A2-4C37-8896-EF5AA94567C9@uva.nl>
To: Michael Schneider <schneid@fzi.de>


I suppose, the least we could do is add a short description of some of  
these equivalencies to the Primer. For instance at [1] to mention the  
equivalence between minCardinality and someValuesFrom. And at [2] to  
say something about equivalentTo vs. subClassOf. Conversely, some  
notions seem intuitively equivalent, but are not, such as functional  
properties and exactly 1 cardinality restrictions.


[1] http://www.w3.org/2007/OWL/wiki/Primer#Adescriptionobjectpropertymincardinality
[2] http://www.w3.org/2007/OWL/wiki/Primer#Aclassequivalentto2way

On 20 mei 2008, at 22:00, Michael Schneider wrote:

> I strongly concur with Bijan's points, and want to add a few more.
> First, I have to apologize to discuss this topic while the issue is  
> still in
> "raised" state. But I cannot attend tomorrow's telco (travelling to  
> Romania),
> so I am going to say, what I would say there, here.
> It is intended that OWL provides different ways to express  
> semantically
> equivalent things, because OWL is not only a reasoning formalism,  
> but also a
> modeling language. That's why we now have owl:disjointUnion, which  
> gives
> additional modeling power to OWL 2 in exchange for forward- 
> compatibility, and
> without enhancing the semantic expressivity of the language.
> OWL 1, btw., also contains a lot of syntactic sugar:  
> owl:equivalentClass can
> be substituted by two rdfs:subClassOf axioms, which would bring  
> certain OWL 1
> ontologies nearer to RDFS. Or there is owl:AllDifferent, or HasValue
> restrictions. Even owl:sameAs can be expressed by means of a nominal- 
> based
> class assertions.
> For the case of >=1-QCRs vs. SomeValues-restrictions: These are pretty
> different modeling tools, which just happen to be equivalent  
> technically. For
> example, it might make sense, from a modeling perspective, to  
> explicitly
> express [1..*] relationships between two classes, or even [0..*]
> relationships, although the latter would be redundant technically.  
> Making
> these features illegal in OWL, and demanding to circumscribe them in a
> technically equivalent way, would not be what I want in such a case.  
> Actually,
> this would be the situation of pre-OWL-2, where it was well known  
> how to
> circumscribe QCRs. But people asked for QCRs often enough, anyway,  
> probably
> not without a reason.
> Even worse than disallowing >={0|1)-QCRs would it be to demand from  
> the OWL
> tools do the transformation themselves. I just try to compare this  
> with the
> strange situation where my Java programming IDE would rewrite all my  
> generics,
> autoboxing, non-indexed loops, and all the other stuff which does  
> not go into
> the bytecode eventually, just in order to make it more Java-1.0  
> compatible. I
> would certainly not use this IDE ever again. :) And then I try to  
> imagine
> Topbraid Composer, which would have to serialize my >=1-QCR silently  
> into a
> SomeValues-restriction. I expect this would probably lead to a lot  
> of traffic
> in Holger's mailing list... :-/
> Cheers,
> Michael
>> -----Original Message-----
>> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org 
>> ]
>> On Behalf Of Bijan Parsia
>> Sent: Monday, May 19, 2008 10:37 PM
>> To: OWL Working Group WG
>> Subject: Re: ISSUE-125 (min1some): Min 1 QCR = someValuesFrom -
>> Serialize as someValuesFrom?
>> So:
>> 	1) intention hiding and non-roundtrippable; plus it frustrates the
>> hell out of users when you silently change what they wrote
>> 	2) non-orthogonal; we need the general form in order to handle
>> larger cardinalities anyway, so would have to impose a rather strange
>> restriction
>> 	3) unnecessary; if users want to write their ontologies this way
>> (so
>> as to be compatible) then can easily do so, or postprocess.
>> Furthermore, you could have a preprocessor before your old tool that
>> did this, no need to build in this kind of strangeness into the base
>> language.
>> I propose closing this, with no change, on these grounds. I don't
>> think we need to note the equivalence in the spec either (there are
>> lots of equivalences...I don't see why this one is particularly
>> interesting).
>> Cheers,
>> Bijan.

Drs. Rinke Hoekstra

Email: hoekstra@uva.nl    Skype:  rinkehoekstra
Phone: +31-20-5253499     Fax:   +31-20-5253495
Web:   http://www.leibnizcenter.org/users/rinke

Leibniz Center for Law,          Faculty of Law
University of Amsterdam,            PO Box 1030
1000 BA  Amsterdam,             The Netherlands
Received on Wednesday, 21 May 2008 07:13:01 UTC

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