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Re: Managing Co-reference (Was: A Semantic Elephant?)

From: Kendall Grant Clark <kendall@clarkparsia.com>
Date: Wed, 14 May 2008 14:25:57 -0400
Cc: Tim Berners-Lee <timbl@w3.org>, Sören Auer <auer@informatik.uni-leipzig.de>, Chris Bizer <chris@bizer.de>, Frank van Harmelen <frank.van.harmelen@cs.vu.nl>, Kingsley Idehen <kidehen@openlinksw.com>, Semantic Web Interest Group <semantic-web@w3.org>, Fabian M. Suchanek <f.m.suchanek@gmail.com>, Tim Berners-Lee <timbl@csail.mit.edu>, jim hendler <hendler@cs.rpi.edu>, Mark Greaves <markg@vulcan.com>, georgi.kobilarov <georgi.kobilarov@gmx.de>, Jens Lehmann <lehmann@informatik.uni-leipzig.de>, Richard Cyganiak <richard@cyganiak.de>, Frederick Giasson <fred@fgiasson.com>, Michael Bergman <mike@mkbergman.com>, Conor Shankey <cshankey@reinvent.com>, Kira Oujonkova <koujonkova@reinvent.com>, Aldo Gangemi <aldo.gangemi@istc.cnr.it>
To: Michael F Uschold <uschold@gmail.com>
Message-Id: <1210787660-sup-5329@k-desktop.int.clarkparsia.com>

Excerpts from Michael F Uschold's message of Wed May 14 12:06:36 -0400 2008:
> 
> **JimHendler *summarized things this way: "So what you are really saying is
> scaling is a technology/research challenge now that there's much more out
> there. We need to go beyond just triple stores and get some fast inferencing
> at Web scales. Makes sense to me."

Absolutely. But it's  gotten harder lately to find support  for that research,
IMO.

We've  been working  on this  for  OWL2 DL-Lite  and for  EL++, two  tractable
profiles of OWL (as  Jim well knows! :>). The next version  of Pellet [1] will
include an EL-optimized  reasoner (though not over secondary  storage), and we
just  released  Owlgres  0.1  [2],  which is  an  OWL2  DL-Lite  reasoner  for
Postgresql for large data sets.

> *MikeUschold *noted that the computational issue of owl:sameAs proliferation
> is a major problem, even if noone is going to load all the semantic web data
> into a single store.  For today's triple stores that do limited inference,
> owl:sameAs "has a significant run time" according both to common sense as
> well as the developers of OpenLink's Virtuoso triple
> store<http://docs.openlinksw.com/virtuoso/rdfsparqlrule.html#rdfsparqlruleintro>
> .
> They say it can easily double query
> times<http://www.openlinksw.com/weblog/oerling/?id=1347>.

You don't have to  do it at query time. Owlgres  does owl:sameAs processing at
load time and so the *query time*  cost is negligible. The usual caveats about
tradeoffs and use cases apply, of course.

Cheers,
Kendall Clark

1 http://pellet.owldl.com/
2 http://pellet.owldl.com/owlgres
Received on Wednesday, 14 May 2008 18:26:45 GMT

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