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RE: DAML-ONT: the case for closedness

From: Hart, Lewis <lhart@grci.com>
Date: Fri, 20 Oct 2000 09:49:40 -0400
Message-ID: <09A65DF294F8D311AAB000105A02DBAF0163E7AB@thumper.va.grci.com>
To: Jeff Heflin <heflin@cs.umd.edu>
Cc: www-rdf-logic@w3.org
  >-----Original Message-----
  >From: Jeff Heflin [mailto:heflin@cs.umd.edu]
  >Sent: Thursday, October 19, 2000 3:31 PM
    >>"Hart, Lewis" wrote:
    >> 
    >> 
    >> To me the definition of 'globally agreed to' means a specified
version
    >> of the ontology, as given by its URL, which everyone who cares knows
    >> about. The kid in the Philippines could publish whatever he wants,
but
    >> it doesn't mean anyone will use it. If an author intends to use the
    >> agreed to meanings, then they must reference the appropriate defining
    >> ontology:
    >> 
    >> <rdf:RDF
    >>   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    >>   xmlns:daml="http://www.w3.org/2000/08/daml-ont#"
    >> 
    >>   xmlns:EC="http://www.e.commerce.org/standards/ontology#"
    >> 
    >>     >
    >>   <EC:Purchase_Order  >
    >>     ... blah blah blah
    >>   </EC:Purchase_Order  >
    >> </rdf:RDF  >
    >> 
    >> If a different ontology (say xmlns:EC="http://hackers.net/ontology")
is
    >> referenced,
    >> then you do not necessarily know what is meant. You may or may not
trust it.
    >> 
  >
  >The problem comes not so much in interacting with a site or exchanging
  >messages between agents (in which case certificates and/or case-by-case
  >acceptance might work sufficiently), the problem comes with an
  >"ontology-based" search engine. Here's an overly-simplified example:
  >
  >Let's say we have the following in our E-commerce ontology:
  >
  >Product isa Thing
  >Computer isa Product
  >...
  >
  >Let's say someone has built the first quantum computer and is offering
  >it for sale. They need to extend the E-commerce ontology with a special
  >QuantumComputerOntology, which might include the following:
  >
  >QuantumComputer isa Computer
  >
  >Finally, on a web page this person now says:
  >
  >Q2000 instance-of QuantumComputer
  >
  >Let's say I'm in the market for a new computer. I might be interested in
  >the QuantumComputer if I knew about it, but if I didn't know about the
  >QuantumComputerOntology beforehand, I couldn't say that I trust this
  >ontology. Thus, my query about Computers will never return this instance
  >b/c I don't believe that "QuantumComputer isa Computer." In this case,
  >it would be nice if my reasoner automatically used the new ontology, so
  >that my query would return the Q2000 as well as more traditional
  >computers.

Agreed. Perhaps the approach to take could be termed "optimistic 
authentication", assume that the ontology is a good thing until
shown otherwise. The onus will be upon the consumers of the ontology 
to determine its goodness, as applied to their domain/problem.

  >
  >However, let's say that some hacker creates an ontology the extends the
  >E-commerce ontology with this beauty:
  >
  >Thing isa Computer
  >
  >Now if my reasoner automatically accepts this ontology, I'm in for a
  >world of trouble. It will tell me that everything is a computer!

It is not the same Thing (pun intended). Remember that there are multiple
namespaces involved. A more exact summary of the ontological statements
above
might be, for the valid case:

ec:Product isa daml:Thing
ec:Computer isa ec:Product
qco:QuantumComputer isa ec:Computer
qco:Q2000 instance-of qco:QuantumComputer

and for the invalid one:

bad:Thing isa ec:Computer

Four different ontologies are in use here: DAML (daml:), eCommerce (ec:),
the QuantumComputerOntology (qco:) and the bogus one (bad:).  What was
actually
said is not all dmal:Things are ec:Computers but just all bad:Things
are ec:Computers. Perhaps this is not even bad in itself, if all that
this ontology discusses are in fact computers.

  >
  >The problem is we want different behaviors depending on our a priori
  >knowledge of the ontology. How do we make sure the right thing is done?
  >I don't want users of the brave new web to be asked every minute by
  >their computers if they accept John Doe's new ontology (which may be
  >very complicated and contain implications that they don't understand),
  >but I also don't want some guy selling widgets out his basement to have
  >to wait 3 months for some certification body to say his ontology is
  >trustworthy before people can even find out that he sells that kind of
  >widgets! That goes totally against the distributed nature of the Web!
  >
  >
  >Jeff

Agreed.

- Lewis
___________________________________________
Lewis L Hart 
GRC International                      lhart@grci.com
1900 Gallows Rd.                  Voice (703)506-5938
Vienna, Va 22182                    Fax (703)556-4261
Received on Friday, 20 October 2000 09:49:46 GMT

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