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Re: KR and RDF Redux

From: Frank Manola <fmanola@mitre.org>
Date: Fri, 22 Nov 2002 17:21:55 -0500
Message-ID: <3DDEAE03.9030905@mitre.org>
To: "Richard H. McCullough" <rhm@cdepot.net>
CC: Jon Hanna <jon@spin.ie>, www-rdf-interest@w3.org

Richard H. McCullough wrote:

> Frank
> You raised a lot of questions, and I don't think it would be helpful for 
> me to try to address every one individually.  Although I'd be  happy to 
> do that off-list if you like.

Maybe at some point, but no time right now (deadlines....)

> In the meantime, I'm going to make a general remarks.  
> 1. You had a long list of concepts with little structure.  If you 
> continue like that you're going to end up with 100,000 properties to 
> describe 10,000 concepts.

Sure, but that depends on the extent to which you want to decompose 
things.  I think, though, you can see from the example I gave that all 
this is doing is taking something like

ex:John ex:wentTo ex:theStore

which bundles a whole lot of interpretation into the parts of one 
triple, and decomposing the ideas into simpler ones (like action verbs 
with agents who are the performers, and so on).  But you still have to 
read meaning into all that stuff;  RDF doesn't provide that meaning. 
All RDF can express is relationships between things.  So all that triple 
means as far as RDF is concerned is that there are two things, ex:John 
and ex:theStore, and there's some relationship called ex:wentTo between 
them.  Strictly speaking, you can't say much about the nature of that 
relationship either.  You can say (in RDF Schema) what its domain and 
range are supposed to be, and you can write triples using other 
properties that further describe the relationship itself, e.g.

ex:wentTo rdf:type ex:verb

but again, all you're expressing, as far as RDF is concerned, is that 
the relationship ex:wentTo, considered now as a thing, has a 
relationship rdf:type with some thing ex:verb.  RDF per se doesn't 
capture what "verbness" is;  just what you claim its relationships with 
other things are.  If I understand your KR example correctly, KR has 
much richer built-in semantics (NB:  I was assuming in your earlier 
message that "KR" referred to "knowledge representation" in general, not 
to a specific notation.  Clearly I missed some earlier context).

> 2. I checked my bookshelf, and I don't own Sowa's "Knowledge 
> Representation"; I suppose that's a recent book?  I don't think I would 
> find any surprises in his book because I have read a number of his 
> papers, and a book which he edited.

Copyright 2000.  It does cover much of his earlier work.

> 3. As for the example:
> English:     John went to the store
> RDFS:      <xx:John> <xx:wentTo> <xx:TheStore>
> KR:           at past { John do go to the store done }
> It was part of my design philosophy for "simplifying English" to avoid 
> changing names to describe verb tenses, plurals, etc.

One of the things Sowa talks about a lot is the relationship of logic to 
various "controlled English" approaches.  The comparison would be 
interesting (but not now!).


Frank Manola                   The MITRE Corporation
202 Burlington Road, MS A345   Bedford, MA 01730-1420
mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875
Received on Friday, 22 November 2002 17:05:09 UTC

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