Re: asymmetric VS non-symmetric

Hi Rinke,

yes, one could add more explanation regarding asymmetric properties  
--- but I doubt whether the primer is the right place: it's a *prime*r  
(as in 'first starting point'), and thus won't be the place to provide  
exhaustive clarifications of all subtleties and explanations of all  
possible misunderstandings. I can think of/remember many questions/ 
misunderstandings of OWL constructors, and also how they interact, and  
I don't want to see  asymmetric properties being singled out as the  
one feature that is explained in depth...

Cheers, Uli

On 2 Sep 2009, at 15:56, Rinke Hoekstra wrote:

> Hi all,
>
> I just had a request from Mark van Assem to add an extra explanation  
> to the primer about asymmetry.
>
> Pascal's addition to the primer [1] is fine:
>
> "Note that being asymmetric is a much stronger notion than being non- 
> symmetric. Likewise, being symmetric is a much stronger notion than  
> being non-asymmetric. "
>
> ... but a bit short and could introduce additional confusion (what  
> then does non-symmetry mean? and non-asymmetric?). Also, it might be  
> helpful to say something along the lines that asymmetry is anti- 
> symmetry + irreflexivity (anti-symmetry and asymmetry are easily  
> confused).
>
> The primer would be the right place for this addition.
>
> -Rinke
>
> [1] http://www.w3.org/2007/OWL/wiki/index.php?title=Primer&diff=25059&oldid=25056
>
>
> On 5 aug 2009, at 09:40, Christine Golbreich wrote:
>
>> 2009/8/4 Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>:
>>> Can we have a diff please.
>>>
>>> Thanks,
>>> Ian
>>
>>
>> - for profiles
>> http://www.w3.org/2007/OWL/wiki/index.php?title=New_Features_and_Rationale&diff=prev&oldid=25076
>> - for asymmetric
>> http://www.w3.org/2007/OWL/wiki/index.php?title=New_Features_and_Rationale&diff=prev&oldid=25052
>>
>> cg
>>
>>
>>> On 4 Aug 2009, at 18:58, Christine Golbreich wrote:
>>>
>>>> Note on asymmetric properties and profiles added in NF&R
>>>>
>>>> cg
>>>> 2009/7/31 Antoine Zimmermann <antoine.zimmermann@deri.org>:
>>>>>
>>>>> Dear all,
>>>>>
>>>>> Until today, I did not look at the semantics of AsymmetricProperty
>>>>> because
>>>>> the word was familiar enough to me to intuitively understand it.  
>>>>> I was
>>>>> however wrongly assuming that the word was used to denote non- 
>>>>> symmetric.
>>>>> From a linguistic perspective, asymmetry is a lack or absence of
>>>>> symmetry.
>>>>> Some mathematical texts use "asymmetric" to simply mean "not  
>>>>> symmetric".
>>>>>
>>>>> I am aware that "asymmetric relation" is often used in  
>>>>> mathematics to
>>>>> denote
>>>>> "strongly asymmetric relation", i.e., no pairs of elements are  
>>>>> related in
>>>>> a
>>>>> bidirectional (symmetric) way. While it is perfectly ok that  
>>>>> OWL2 defines
>>>>> AsymmetricProperties the way it does, I am surprised not to find  
>>>>> *any*
>>>>> remark, neither in the formal specs, nor in the UFDs, nor in the  
>>>>> mailing
>>>>> list archives, about the fact that AsymmetricProperty is not the
>>>>> complement
>>>>> of SymmetricProperty.
>>>>>
>>>>> I am sure that other people are understanding asymmetry in the  
>>>>> same way
>>>>> as I
>>>>> did, so I'd suggest adding a small sentence in the Primer (Sect. 
>>>>> 6.1 [1])
>>>>> and
>>>>> NF&R (Sect.2.2.3 [2]) stating that "asymmetric" is not the  
>>>>> negation of
>>>>> "symmetric". Since the UFDs are still in LC, this should be  
>>>>> addressed
>>>>> somehow.
>>>>>
>>>>> [1]
>>>>>
>>>>> http://www.w3.org/TR/2009/WD-owl2-primer-20090421/#Property_Characteristics
>>>>> [2]
>>>>>
>>>>> http://www.w3.org/TR/2009/WD-owl2-new-features-20090421/ 
>>>>> #F6:_Reflexive.2C_Irreflexive.2C_and_Asymmetric_Object_Properties
>>>>>
>>>>> Regards,
>>>>> --
>>>>> Antoine Zimmermann
>>>>> Post-doctoral researcher at:
>>>>> Digital Enterprise Research Institute
>>>>> National University of Ireland, Galway
>>>>> IDA Business Park
>>>>> Lower Dangan
>>>>> Galway, Ireland
>>>>> antoine.zimmermann@deri.org
>>>>> http://vmgal34.deri.ie/~antzim/
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Christine
>>>>
>>>
>>>
>>
>>
>>
>> -- 
>> Christine
>
>
>
>
>
> ---
> Drs Rinke Hoekstra
>
> Leibniz Center for Law      |  AI Department
> Faculty of Law              |  Faculty of Sciences
> Universiteit van Amsterdam  |  Vrije Universiteit
> Kloveniersburgwal 48        |  De Boelelaan 1081a
> 1012 CX  Amsterdam          |  1081 HV Amsterdam
> +31-(0)20-5253499           |  +31-(0)20-5987752
> hoekstra@uva.nl             |  hoekstra@few.vu.nl
>
> Homepage: http://www.few.vu.nl/~hoekstra
>
>
>
>
>
>

Received on Thursday, 3 September 2009 11:51:26 UTC