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Re: ISSUE-149: Last Call Comment: Asymmetric associations

From: Sean Bechhofer <sean.bechhofer@manchester.ac.uk>
Date: Fri, 24 Oct 2008 11:04:43 +0100
Message-Id: <BBFC5F4D-0C74-43F4-AD03-254B6ECC12E1@manchester.ac.uk>
Cc: Alistair Miles <alistair.miles@zoo.ox.ac.uk>, public-swd-wg@w3.org
To: Antoine Isaac <aisaac@few.vu.nl>


On 22 Oct 2008, at 20:16, Antoine Isaac wrote:

>
> Hi,
>
> I agree with the decison, on not introducing a subproperty of  
> skos:related that is directional.
> Yet I wonder whether the last part is captured: Erik mentions what  
> seems to be links of type broader/narrower that are somehow not  
> entail transitive hierarchical links, that is,  
> skos:broaderTransitive statements. How such a thing would be  
> possible, even if we accepted the requirement?

It's not possible to do this with our current design. Any subproperty  
<p> of skos:broader will be a subproperty of skos:broaderTransitive,  
so one will be able to query over the a property that includes the  
transitive closure of <p> (and potentially other things) via  
broaderTransitive.

We can't avoid this unless we change our use of the "transitive  
superproperty pattern". The alternative would likely be returning to  
a situation where skos:broader itself is transitive, which will still  
not solve Erik's "problem" as one would be able to query the  
transitive closure of <p> using skos:broader.

Note that neither of these solutions necessarily result in  
entailments about <p> itself.

> Antoine
>
>> Here is a draft response to Erik on ISSUE-149, comments welcome.
>>
>> --- begin draft response ---
>>
>> Dear Erik,
>> Many thanks for your helpful comments. In response to your comment
>> below:
>>
>> On Wed, Oct 01, 2008 at 09:17:15PM +0000, SWD Issue Tracker wrote:
>>
>>> ISSUE-149: Last Call Comment: Asymmetric associations
>>> http://www.w3.org/2006/07/SWD/track/issues/149
>>>
>>> Raised by: Alistair Miles
>>> On product: SKOS
>>>
>>> Raised by Erik Hennum in [1]:
>>>
>>> """
>>> In our experience, while we've had no need for symmetric  
>>> associations,
>>> we've had considerable need for directional, non-hierarchical  
>>> associations.
>>> For instance, our target audience perceives a directional  
>>> association
>>> between a hardware platform and the operating systems that run on  
>>> the
>>> platform and again between an operating system and the software
>>> applications that run on the operating system.
>>>
>>> In Section 8.6.3. Symmetry of skos:related, the draft makes a  
>>> point of
>>> providing examples of asymmetric subproperties of skos:related,  
>>> suggesting
>>> that our experience may not be unusual.
>>>
>>> Is this requirement sufficiently common that it makes sense to  
>>> provide an
>>> asymmetric subproperty of skos:related as part of the standard  
>>> rather than
>>> have many adopters solve the same problem in different ways?   
>>> Effectively,
>>> this subproperty would be a broader / narrower relationships that  
>>> does
>>> _not_ entail or imply the weak transitive associations that  
>>> construct the
>>> hierarchy.
>>> """
>>>
>>
>> While we are sympathetic to these requirements, at the current  
>> time we
>> propose to postpone development of a standard solution and leave it
>> for future working groups or for third party extensions developed
>> within the community of practice. Both the SKOS Reference (section
>> 8.6.3) and the SKOS Primer (section 4.7) currently provide  
>> examples of
>> how to develop third party extensions to SKOS semantic relations. Can
>> you live with this?
>>
>> Kind regards,
>>
>> Alistair
>> Sean
>>
>>
>>> [1] http://lists.w3.org/Archives/Public/public-swd-wg/2008Jun/ 
>>> 0103.html
>>>
>>
>>
>
>

--
Sean Bechhofer
School of Computer Science
University of Manchester
sean.bechhofer@manchester.ac.uk
http://www.cs.manchester.ac.uk/people/bechhofer
Received on Friday, 24 October 2008 10:06:01 GMT

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