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Re: Comment on RDF Mapping: variables in sequence pattern

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 28 Jan 2009 11:09:28 -0500 (EST)
Message-Id: <20090128.110928.113772293.pfps@research.bell-labs.com>
To: ian.horrocks@comlab.ox.ac.uk
Cc: msmith@clarkparsia.com, public-owl-wg@w3.org

Nope, at least as far as I can see, and, at the direction of the WG,
I've already changed the document accordingly (ACTION-266).

peter


From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Subject: Re: Comment on RDF Mapping: variables in sequence pattern
Date: Wed, 28 Jan 2009 09:08:46 +0000

> 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 16:06:59 GMT

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