Re: DAML-S expressiveness challenge #1

On July 9, Thomas B. Passin writes:
> [Ian Horrocks" <horrocks@cs.man.ac.uk>
> To: "David Martin]
> 
> > What you really want to say is that that the class of
> > persons who buy diapers is exactly the same as the class of persons
> > who parented some other person. To do this you should use a
> > sameClassAs assertion along the lines of (using a pseudo-syntax):
> >
> 
> I think it's a good idea to get questions like this set out as clearly and
> simply as possible before inventing new syntax or vocabulary for them.

Sorry if the pseudo-syntax offended you - I wasn't really intending to
invent new syntax but just to abbreviate the DAML+OIL RDF syntax, which
is rather cumbersome for such exchanges as this (someone did promise
to come up with a "human readable" syntax, but we are still waiting).

>  If
> you were using predicate logic or KIF, I imagine you'd arrive at something
> like this:
> 
> for all persons x it is not true that:
>     ((x bought diapers) and (x is not a parent))

Using FOL is fine by me, although it has the disadvantage that the
translation into DAML+OIL isn't always obvious. However, I don't think
that what you have written does the trick - it certainly isn't
equivalent to the "pseudo" DAML+OIL I wrote. As I understood it, we were
trying to express that people buy diapers if and only if they are
parents. What you have written says that people buy diapers only if
they are parents. What you needed was to say:

for all persons x it is not true that:
    (((x bought diapers) and (x is not a parent)) 
    or ((x not bought diapers) and (x is a parent)))

> With conceptual graphs it might be easier to read, but even this way it
> doesn't seem too complex.  What we want is a way to define some kind of
> relationship, property, or situation (take your pick according to
> circumstances) that expresses the above.  (I know I am glossing over the
> definitions of "bought diapers" and "is a parent"). So David's question
> could be viewed as having two parts:
> 
> 1) Is there a way to express the above assertion?  And if so,
> 2) Is there a way to define a new term as a shorthand for that expression?

I was under the impression that we were trying to express it in
DAML+OIL and I showed how to do that. If we can express it in DAML+OIL
then we can obviously express it in KIF or CGs as DAML+OIL is a proper
subset of FOL.

> I suggest that these questions should be answered before getting into
> questions of classes of persons (Ian's suggestion, above) versus assertions
> about persons (my example), for instance.
>
> I just encountered DAML-S last night for the first time, so I have no
> opinion on this specific question.  I certainly hope that 1), at least, can
> be answered "yes".  The answer to 2) would be "yes" for conceptual graphs
> (and KIF, I believe).
> 
> Forgive me if I have missed the point, since I am new to the list and to
> this discussion.
> 
> Regards,
> 
> Tom P

Regards, Ian

Received on Monday, 9 July 2001 19:25:45 UTC