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Re: Semantics, Web services and the Semantic WEB

From: Francis McCabe <fgm@fla.fujitsu.com>
Date: Tue, 28 May 2002 22:17:58 -0700
Cc: www-ws-arch@w3.org, "David W. Levine" <dwl@watson.ibm.com>
To: "Champion, Mike" <Mike.Champion@SoftwareAG-USA.com>
Message-Id: <7079DA6D-72C3-11D6-AA03-000393A3327C@fla.fujitsu.com>

Mike:
  Glad you liked the post.

  I'll try to show light on some of the issues you raised.

>
> Thanks for a very informative post!
>
> One question:  you mention that the semantic web builds on predicate 
> logic
> ....
>
>> predicate logic makes an admirable graph notation and
>> Ontology is the discipline that
>> has had most to say about these semantic nodes.
>
> but does not try to assert a global set of axioms ...
>
>> One point to note about the Semantic WEB approach that is very
>> interesting: viewed as an Ontology building system (which it is)
>> the vision is that there will not be a single definitive Ontology,
>> or even a single `upper ontology'. Instead, there are likely to
>> be many ontologies and many cross links between them: its an
>> ontology web rather than an ontology tree.
>
> My (limited, amateurish) understanding of the role of formal logic in 
> human
> affairs is that the big challenge is to come up with a consistent set of
> axioms on which to perform valid inferences but is rich enough to be of
> practical significance.  As a practical matter, this has only happened 
> in a
> limited number of disciplines, and required centuries of effort.  The 
> lack
> of consistency renders the exercise utterly futile; for example, the
> oft-cited anecdote (or joke, or whatever it really is):

The main reason that centuries of effort were required is that they 
didn't have computers ;-)


>
>   Bertrand Russell mentioned that a false proposition implies any
>   conclusion. A student raised his hand and said "given that 1 = 0,
>   prove that you are the Pope". Russell immediately replied,
>   "Add 1 to both sides of the equation: then we have 2 = 1.
>   The set containing just me and the Pope has 2 members.
>   But 2 = 1, so it has only 1 member; therefore, I am the Pope."


There isn't anything fundamentally different from writing an axiom or 
writing a program. You can also create havoc with Java ;-)



>
> So, what hope is there that useful logical inferences could be made 
> using
> cross-linked ontologies that have not undergone rigorous scrutiny to 
> ensure
> their mutual consistency?  Or is the type of inference required to reach
> useful conclusions on the semantic web of a more heuristic variety than
> textbook logic?  For example, if one finds vastly more RDF pathways that
> lead to the conclusion that Karol Wotilya is the Pope than one finds  
> that
> conclude the Bertrand Russell is the Pope, is that good enough? (FWIW, a
> Google search to dig up the Bertrand Russell joke got a lot more hits 
> than a
> Google query to find out the current pope's given name!).


A `normal' WEB bot looks for strings that it is interested in. The big 
problem with that is that it will register as a positive hit any web 
page that has the text "this page is not intended for adults" as a 
suitable place to go for adult entertainment.

A parallel search using concept maps; especially where the concept map 
is written in a reasonable powerful logic, will be able to take into 
account the `little words' like `not' and `some' etc.

However, you're still not guaranteed a perfect match. On the other hand, 
if the match IS good then you're in much better shape than a normal WEB 
bot as you've also got all those pointers to web services.



>
>
>> The WS-Arch WG could, and should, make its requirements clear to the
>> SWI. It is hard to imagine the W3C having two competing
>> technologies for  describing semantics.
>
> I personally think that given the state of immaturity of semantic 
> theory and
> technology, and given the limitations of RDF and DAML that you 
> mentioned,
> that it WOULD be quite appropriate for the W3C to have competing
> technologies for describing semantics.  This seems like a time for
> exploration, and standardization can come when we understand what really
> works well.  The W3C works best as a forum for coordinated exploration 
> of
> promising alternatives in a way that minimizes gratuitous 
> interoperability
> differences. It does not work well when it tries to do "computer 
> science by
> committee" that immediately leads to standardization.
>

Well, I have an axe to grind here. My colleagues and I have been working 
on strongly typed logics for a number of years. But, I still don't think 
that the W3C will have more than one semantic notation. I do think that 
its entirely appropriate for web services to send a strong message to 
the semantic web folk -- call it a wake up call!
Received on Wednesday, 29 May 2002 03:09:13 GMT

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