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LANG: Knowing where thing come from (was Re: Lang: owl:ontolgy )

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Thu, 19 Sep 2002 17:42:33 -0400
Message-ID: <3D8A44C9.EE764134@cse.lehigh.edu>
To: Christopher Welty <welty@us.ibm.com>
CC: www-webont-wg@w3.org


Just to refresh everyone's memory, this discussion began because of the
proposals for handling imports that are based in XML/RDF syntactic
inclusion. My whole point is that in every approach I've seen so far,
this form of inclusion loses track of which statements come from which
ontologies. In these cases, I no longer have the URLs of the documents;
they were lost when one document was inserted into another. If all OWL
parsers must perform this kind of inclusion, then people like me lose
the ability to do the things I mentioned.

Note, I was not arguing that we need to modify RDF or OWL in some
radical way so that the model inherently includes source information
(I'll save that battle for OWL 2.0 :-). I simply want to make sure we
have solutions that don't prevent people who need source information
from doing what they want.


Christopher Welty wrote:
> I think I generally agree that "knowing where things come from" should not
> be part of OWL, per se.  I think in your example that, (as I believe Dan
> was saying in the telecon) if your search engine needs to know about where
> things come from, it can keep track of it as it sucks stuff in.  In fact,
> that is what contemporary search engines do with web pages they index -
> the information about the location of the information is NOT in the HTML
> the engines index (it can be of course, but it usually isn't), it is part
> of the data model of the index.  The engine records the URL of a page when
> it sucks in the page.  So if that's your use case, I'm not convinced.
> I do, on the other had, think imports and versioning are good ideas.
> -Chris
> Jeff Heflin <heflin@cse.lehigh.edu>
> Sent by: www-webont-wg-request@w3.org
> 09/19/2002 11:52 AM
>         To:     pat hayes <phayes@ai.uwf.edu>
>         cc:     www-webont-wg@w3.org
>         Subject:        Re: Lang: owl:ontolgy (was RE: LANG: syntactic version for  imports (and
> other things))
> Pat,
> You asked why I think it is important to know where the information came
> from. The short answer is that you yourself admit that this information
> would be needed for performing trust or truth maintenance. Isn't it
> enough to say that we shouldn't build a design that rules out such
> applications?
> If that answer isn't good enough for you, let me describe a personal use
> case. Over the last five years I have been interested in building
> semantic web search engines. One of the things I realized though, is
> that such search engines should just reason with every single ontology
> that's ever been published. That is sure to lead to chaos due to
> contradictions, different opinions, etc. However, at the same time, I
> don't want to have to design a separate search engine for every domain
> because there ends up being a lot of duplication in each engine's
> repository (that is, if you want any kind of integration). So, what I
> think the right approach is to store all of the information in one
> repository, but have reasoning algorithms that can only use parts of it
> at a single time. Ideally, a user can say, "I have this query Q and I
> want you to answer it using only the semantics of the ontologies O1, O4,
> and O5)." For such an approach to work, the repository must know which
> statements come from which ontologies.
> You also said:
> > Seems to me it is why 'imports' is irrelevant. Look, you just said,
> > we do not want to reason with all the descriptions... OK, so why do
> > we need a pointer to more descriptions? This seems like saying that
> > we don't want all the water, so we need to know where more water is.
> > This just doesn't seem to follow: theres a premiss missing somewhere.
> > (OK, Ian's point on todays phone call about completeness is well
> > taken; but you aren't making that point here, right?)
> Actually my point is the same as the completeness one. Let me put it
> this way: we don't want to reason with everything everybody ever said
> about a class, but when we are reasoning about a document, it would be
> nice if that document's author could say "here are other things that I
> agree with, and I sanction any inferences you draw when you combine
> these documents with my document."  You may also want to see my message
> to Dan Connolly for more arguments on the need for imports [1].
> Jeff
> [1] http://lists.w3.org/Archives/Public/www-webont-wg/2002Sep/0121.html
> ).
Received on Thursday, 19 September 2002 17:42:36 UTC

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