Re: asymmetric VS non-symmetric

The proposed text has the advantage that it clarifies the difference  
between asymmetry and anti-symmetry, but it has the disadvantage that  
it no longer says anything about asymmetry being much stronger than  
non-symmetry (i.e., lack of symmetry), something that was added in  
response to an earlier comment. If any change is to be made then it  
would have to be in addition to what is there now, perhaps something  
like:

"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.
Moreover, asymmetry is a stronger notion than anti-symmetry as it  
requires that
the relationship is also irreflexive."

I agree with Uli's point that the primer needs to be kept short and  
shouldn't be expected to "provide exhaustive clarifications of all  
subtleties and explanations of all possible misunderstandings".  
However, I can live with the above modest expansion if others can.

Ian



On 4 Sep 2009, at 09:20, Rinke Hoekstra wrote:

> Hi,
>
> Guess I agree with both of you ;)
>
> On 3 sep 2009, at 14:34, mark@few.vu.nl wrote:
>> "Note that asymmetry is a stronger notion than anti-symmetry as it  
>> requires that
>> the relationship is also irreflexive."
>
> That looks good.
>
>> Create links for the terms "asymmetry", "anti-symmetry" and  
>> "irreflexivity"
>> (e.g. wikipedia) and it's what I would need from a "primer".
>
> I disagree. Wikipedia pages tend to change, and are outside the  
> control of the WG, the W3C, nor subject another trusted editorial  
> process (as RFC's or ISO).
>
> Your proposed wording should be enough.
>
> -Rinke
>
>>
>> Regards,
>> Mark van Assem.
>>
>>> 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
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
>
>
> ---
> 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 Friday, 4 September 2009 09:38:52 UTC