Re: Dealing with qualified expressions in DAML

From: David Martin <martin@ai.sri.com>
Subject: Re: Dealing with qualified expressions in DAML
Date: Wed, 18 Sep 2002 07:59:58 -0700

[...]

> > > How does that get to be a legitimate inference?  Intuitively, I can't see a shred
> > > of basis for it.
> >
> > It is not a legitimate inference.
> >

> Thanks.  I'm relieved that it's not a legitimate inference.  But then I
> have to admit I still can't make sense of your statement:
> 
> (2) "a side effect is to assert that each of the restrictions thus formed
> has the same extension. ."
> 
> Clearly we understand one or more of the words in (2) differently - and I
> suspect it has to do with "side effect" and "assert".

How about:

    It is a logical consequence of the information specified that each of
    the restrictions thus formed has the same extension.

> I'm not that concerned to get additional clarification; you've already
> addressed our questions with respect to our tool building effort.
> (Again, thanks.)  But if you feel like giving additional clarification, I
> would suggest that you do one of the following:

> (a) state in a formal notation some legitimate inference from the
> CartoonCharacter class definition above, which illustrates your statement
> (2), but is *not* illustrative of "The extension of the restriction is
> then the intersection of all of them."

It is a logical consequence of the information specified that

     {things with at most 1 elephant in their pocket}
     has exactly the same elements as 
     {things with at most 2 elephants in their pocket}

> (b) explain some practical consequence of (2) - say, for a parser builder

A parser builder doesn't have to worry, such constructs are syntactically
legal.  A user interface should prevent users from constructing such
constructs and should complain bitterly if an ontology with such constructs
is used.

> OR
> 
> (c) Give a pointer to a paper or other document that explains the idea
> behind (2). 

The DAML+OIL model theory, available at
http://www.daml.org/2001/03/model-theoretic-semantics, provides a formal
definition of what is going on.  

> Regards,
> David Martin

Peter F. Patel-Schneider
Bell Labs Research

Received on Wednesday, 18 September 2002 11:07:00 UTC