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Re: [OWL compatibility] #, ## in OWL compatibility

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Thu, 10 Sep 2009 11:30:24 -0400
To: Chris Welty <cawelty@gmail.com>
Cc: Jos de Bruijn <debruijn@inf.unibz.it>, RIF <public-rif-wg@w3.org>
Message-ID: <20090910113024.1934f0f6@kiferserv>


On Thu, 10 Sep 2009 10:59:03 -0400
Chris Welty <cawelty@gmail.com> wrote:

> 
> I was under the impression that option #3 was specifically not chosen because it 
> leads to some undesirable property in BLD/OWL-DL combinations. 

This impression is wrong, as I understood from talking to Jos.

> Also, doesn't 
> BLD allow the range and domain of # to be much larger than OWL-DL does for type?

That has already been taken care of by the restrictions imposed by RIF/OWL-DL
combo.

> You will also have a hard time convincing me that #3 is a bug fix.

In RIF-RDF and RIF-OWL-Full combos, rdfs:subclassOf is related to ## and
rdf:type to #. In contrast, there is no relationship between these in the
RIF-OWL-DL combo. Why? 
This discrepancy was papered over in the text and it is reasonable to assume
that the reader would assume otherwise (as I did).

> I prefer option 2, and I would include in the additional text that combinations 
> that map type and subclass between BLD and OWL-2 remains a research topic.

Is it?

michael


> Jos de Bruijn wrote:
> > In RIF-RDF combinations, there is a one-to-one correspondence between
> > rdf:type statements and # statements, and ## statements imply
> > rdfs:subClassOf statements, so:
> > 
> > a#b  iff a[rdf:type -> b]   and
> > a##b implies a[rdf:subClassOf -> b]
> > 
> > 
> > These correspondences also hold in RIF-OWL Full combinations, since
> > their semantics simply extends the semantics of RIF-RDF combinations.
> > 
> > Now, since the semantics of RIF-OWL DL combinations is completely
> > different, these correspondences do not automatically carry over.  In
> > fact, in such combinations there is no relationship between # and ##
> > statements in RIF, on the one hand, and typing and subclass statements
> > in OWL DL, on the other.  A minimalistic approach was taken in the
> > specification of the semantics of RIF-OWL DL combinations:
> > -OWL class membership statements A(?x) correspond to RIF statements
> > ?x[rdf:type -> A]
> > -property value statements R(?x,?y) correspond to RIF statements ?x[R -> ?y]
> > 
> > There are no further correspondences between statements in OWL DL and in
> > RIF.  However, some users may expect to be able to use # and ##
> > statements to access OWL class membership; the document currently does
> > not explain that this is not possible.
> > We could do one of three things:
> > 1- leave things as they are, assuming that # and ## are not of interest
> > to users of RIF-OWL DL combinations
> > 2- explain the use of # and ## in the document (this would certainly not
> > be a substantive change, so we should not run into procedural problems)
> > 3- define the semantics of # and ## in RIF-OWL DL combinations in a
> > similar fashion as in RIF-RDF combinations: a one-to-one correspondence
> > between # and OWL class membership statements and implication between ##
> > and OWL subclassing.  Technically, this is not a problem.  In principle,
> > it would be a substantive change, but we might be able to argue that it
> > was a bug in the specification.
> > 
> > I am fine with any of the options.  Clearly, option 1 would be least
> > work for me, followed by option 3.
> > Opinions?
> > 
> > Best, Jos
> 
Received on Thursday, 10 September 2009 15:31:06 GMT

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