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Re: Comment on RDF Mapping: variables in sequence pattern

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Wed, 28 Jan 2009 09:08:46 +0000
Message-Id: <87D175B0-1490-481E-BD4C-803E49EC4472@comlab.ox.ac.uk>
Cc: msmith@clarkparsia.com, public-owl-wg@w3.org
To: Peter F. Patel-Schneider <pfps@research.bell-labs.com>

The "big club" clearly does the job, is easy to understand, and I  
don't see any serious disadvantages -- am I missing something?

Ian


On 7 Jan 2009, at 18:24, Peter F. Patel-Schneider wrote:

>
> [Again, not an official reply.]
>
> It does appear to me that the rules for reverse mapping of  
> sequences are
> not complete.    Two lists that share an intermediate node can be
> (non-deterministically) accepted.  This includes strange lists that  
> loop
> back to themselves (and that also have a valid tail).
>
> A "big club" fix would be to have a global constraint along the lines
> of:
>
> 	No blank node can be used in more than once in these patterns.
> 	(This means that all lists are non-cyclic and do not share
> 	tails.)
>
> It might also be possible to have a more targetted fix, along the  
> lines
> of the method used when parsing class expressions.
>
> peter
>
>
>
>
> From: "Mike Smith" <msmith@clarkparsia.com>
> Subject: Comment on RDF Mapping: variables in sequence pattern
> Date: Tue, 6 Jan 2009 09:53:10 -0500
>
>>
>> While verifying some WebOnt test cases against the RDF to structural
>> mapping defined at [1], I noticed that there is no constraint
>> preventing variables within the sequence pattern from matching the
>> same node (see the second row of Table 3 at [1]).  I found this
>> problematic, particularly when trying to avoid things like cyclic
>> lists (as in the nonconclusion ontology of [I5.5-006]).
>>
>> I believe that adding the constraint to the mapping document will
>> clarify the expected behavior.
>>
>> -- 
>> Mike Smith
>>
>> Clark & Parsia
>> http://clarkparsia.com/
>>
>> [1] http://www.w3.org/TR/2008/WD-owl2-mapping-to-rdf-20081202/ 
>> #Mapping_from_RDF_Graphs_to_the_Structural_Specification
>> [I5.5-006] http://km.aifb.uni-karlsruhe.de/projects/owltests/ 
>> index.php/TestCase:WebOnt-I5.5-006
>>
>>
>
Received on Wednesday, 28 January 2009 09:09:41 GMT

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