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Re: [ontolog-forum] Next steps in using ontologies as standards

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Ed Barkmeyer <edbark@xxxxxxxx>
Date: Thu, 08 Jan 2009 19:23:37 -0500
Message-id: <49669909.8020104@xxxxxxxx>
Len,    (01)

you wrote:    (02)

> The main reason Codd's algebra is not suitable for constructing
> ontology and in general for sharing knowledge - is not that operators
> like "join" are opaque. Main reasons are soundness, decidability
> and computability of any relational algebra. I am not an expert
> to provide specific references, but I know enough to understand
> why Description Logic is considered to be the only practical
> framework for sharing knowledge.    (03)

With all due respect, you haven't listened closely enough to the various 
sides of that discussion.  Description Logic is not "widely" considered 
to be the most useful framework, let alone the only practical one.  It 
is considered to be practical for Semantic Web purposes -- assisting in 
the search for information relevant to a topic by marking up documents 
as to their content, where content is defined by an ontology.  And 
_some_ OWL/DL ontologies can be strong enough to be useful in other ways.    (04)

IMO, the main advantage of OWL in the Web community is that it has begun 
to squelch the idea that XML Schema is an information modeling language. 
  OWL/DL is somewhat more capable of representing knowledge than UML 
class diagrams, and it is rigorously defined, which is a major plus.  So 
it is a good language for producing domain models, and it encourages 
much better practice in the communities that formulate exchange 
standards, another major plus.    (05)

How good it is as a language for capturing knowledge models used for 
formal reasoning is "quite another thing entirely".  DL is not a silver 
bullet.  You have to give up a lot of expressiveness to get the strong 
computational bounding that is characteristic of tableaux reasoning.    (06)

> This had been discussed on this forum many times, often comparing
> Prolog and OWL as representing competing alternatives for encoding
> knowledge. The jury is still out on it, I think.    (07)

Indeed.  Each has its place in the larger world of knowledge 
engineering.  And so do First-order logic reasoners, and some others.    (08)

> But it should be clear that simply translating SQL to English is not
> a viable approach.    (09)

Now as to that, I fully agree.  (Sorry, Adrian.)    (010)

-Ed    (011)

Edward J. Barkmeyer                        Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Stop 8263                Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263                FAX: +1 301-975-4694    (012)

"The opinions expressed above do not reflect consensus of NIST,
  and have not been reviewed by any Government authority."    (013)

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