Re: Good and Bad IS-A hierarchies (Pat Hayes)
Message-id: <>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Date: Wed, 26 Jul 1995 14:42:46 -0500
To: (Fritz Lehmann),,
From: (Pat Hayes)
Subject: Re: Good and Bad IS-A hierarchies
Precedence: bulk
Thanks, Fritz. I am aware of what is-a heirarchies accomplish, and the way
in which they allow the statement of compact generalizations and achieve
dramatic speedups when they can be constructed. I was Cohn's doctoral
adviser, in fact.

My point was not that is-a is a Bad Thing, but that sometimes there are
genuinely incompatible axioms which you have to choose between. This isnt
any kind of heirarchy, and certainly not a classification heirarchy on the
property names involved. Life is not a box of chocolates.


Until September: 
1916 Ivy Lane, Palo Alto, Ca. 94303               phone (415)855 9043