Re: Frames are (almost) enough for EDI (Paul van der Vet)
Date: Wed, 21 Sep 94 10:28:30 +0200
From: (Paul van der Vet)
Message-id: <>
Subject: Re: Frames are (almost) enough for EDI
In-reply-to: Mail from ' (Pat Hayes)'
      dated: Tue, 20 Sep 1994 13:04:38 +0000
Precedence: bulk

Pat Hayes wrote to the list srkb:

[... a lot deleted ...]
> This is one of the problems with the formalisms we have, I think: they
> force one to take a stance on issues which are not really important to the
> task in hand and which later get in the way. (Is a fitted carpet IN a room
> or PART OF the room? How about the paint on the wall?) [...]

I wonder whether these issues are not really important. Different sets
of axioms make for different consequence sets. The carpet example only
poses a problem if there is a real difference between IN and PART
OF. Suppose that we use both, and that (as seems reasonable) both the
IN and the PART OF are transitive. Then, if the carpet is IN the room
we cannot conclude that it is IN the house if there is an axiom saying
that the room is PART OF the house but no axiom saying that the room
is IN the house.

Now the carpet example is perhaps not so clarifying because it deals
with common-sense knowledge. Common-sense knowledge doesn't give you
much to hold on to anyway, so even if you do inspect consequence sets
you often find yourself wondering whether the differences matter. You
cannot blame first-order logic because you are by necessity solving
two problems in one stroke: (1) organising an otherwise unorganised
bunch of intuitions which might moreover differ from person to person;
and (2) expressing what you have found in first-order logic. I suggest
that in dealing with common-sense knowledge the first problem is the
handicap. One argument is that in mature scientific and engineering
domains part of the intuitions have become "codified" in an attempt at
establishing a common ground for discussion. This eases (but does not
solve) the first problem. Generations of philosophers of science have
studied formalisations of scientific theories. They have shown that
the choice of axioms is critical and that it makes sense to discuss
such choices. Here, too, there is not a single choice that is right
for every application, but we have at least some ideas about the pros
and cons of our choices.

Paul van der Vet.

Paul van der Vet                   Phone +31 53 89 36 94 / 36 90
Knowledge-Based Systems Group      Fax   +31 53 33 96 05
Dept. of Computer Science          Email
University of Twente
P.O. Box 217
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The Netherlands