W3C home > Mailing lists > Public > www-rdf-logic@w3.org > October 2000

Re: DAML-ONT: the case for closedness

From: Jeff Heflin <heflin@cs.umd.edu>
Date: Thu, 19 Oct 2000 15:30:52 -0400
Message-ID: <39EF4BEC.748BE87E@cs.umd.edu>
To: "Hart, Lewis" <lhart@grci.com>
CC: www-rdf-logic@w3.org
"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

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!

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!

Received on Thursday, 19 October 2000 15:30:59 UTC

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