Re: Non-global Keys

This decision is acceptable to me.

- Bob

At 01:53 PM 7/15/2003 -0400, Jim Hendler wrote:
>Dear Bob-
>  Thank you for your comment, the working group has considered it 
> carefully.  With respect to qualified keys, we considered how this could 
> be added to OWL - see the discussion thread starting at [1] and 
> particularly [2].  The group considered the addition of Qualified 
> Cardinality Restrictions, which we believe are needed to implement the 
> sort of global keys you need.  However, the WG decided to postpone the 
> issue of QCRs as discussed in my response to Alan Rector at [3].
>  We also considered the issue of Compound Keys.  We decided this was an 
> important enough area to open an issue on our issues list explicitly.  We 
> did not, however, come up with  a solution as to how to address 
> these.  Instead we also decided to postpone this issue. The issue text is:
>
>>TITLE: Compound Keys
>>DESCRIPTION:
>>   Relational Databases often use keys that are composed of multiple 
>> fields.  OWL allows keys using owl:InverseFunctionalProperty for a 
>> single field (property).  It would be desirable for OWL to provide the 
>> compound keys capability as well.
>>STATUS: POSTPONED
>>RAISED BY: J. Hendler based on a Last Call comment raised by Bob 
>>MacGregor: 
>>http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0019.html
>>
>>Closing Comments:
>>
>>While compounds keys would be desirable to add, there is some difficulty 
>>in adding them in the current OWL syntax, similar to the problem arising 
>>for "qualified" properties (see discussion under issue 3.2).  In 
>>addition, for the OWL DL profile, it is still something of a research 
>>issue  (c.f. 
>>http://www.dis.uniroma1.it/~calvanes/papers-html/DL-2000.html) as to how 
>>these are best realized by DL reasoners.  There is also a question as to 
>>whether mixing datatype and object type in a compound key would be 
>>allowed, and whether it would cause difficulties to reasoners.
>
>
>Please let us know if this decision to (a) acknowledge that our
>design is lacking, but (b) postpone further design work to a future
>version is acceptable.
>    -Jim Hendler
>
>
>[1]
>http://lists.w3.org/Archives/Public/www-webont-wg/2003May/0064.html
>[2] http://lists.w3.org/Archives/Public/www-webont-wg/2003May/0085.html
>[3]
>http://lists.w3.org/Archives/Public/public-webont-comments/2003Jun/0024.html
>
>
>--
>Professor James Hendler                           hendler@cs.umd.edu
>Director, Semantic Web and Agent Technologies     301-405-2696
>Maryland Information and Network Dynamics Lab.    301-405-6707 (Fax)
>Univ of Maryland, College Park, MD 20742          *** 240-277-3388 (Cell)
>http://www.cs.umd.edu/users/hendler      *** NOTE CHANGED CELL NUMBER ***

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Robert MacGregor
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