Good and Bad IS-A hierarchies (Fritz Lehmann)
Date: Wed, 7 Jun 95 17:01:44 CDT
From: (Fritz Lehmann)
Message-id: <>
Subject: Good and Bad IS-A hierarchies
Precedence: bulk

     Peter Clark wrote, among other things, this:
-----begin quote----

What I wouldn't like to
now see is a lot of isa-hierarchies published, with little or no information
in the general/top-level concepts.
----end quote----

     The key thing is the "little or no information".  I _would_ like
to see generally  useful IS-A hierarchies published, provided they
explicity state what information is contained in each concept --
what can be inherited.  Also there is a lot of important Large-scale
structure stuff that normally goes unaddressed, like the different
notions of "dimension" in Bruce Porters, Doug Skuce's, CYC's (slot-
based still?) and my theories.  I don't know how the Pangloss
Ontology handles this; I've never seen the ontology itself.

----begin quote----
... For example, your ontology may model a room as a container but I want to
model it as a point location (or person as a thing/process, carpet as
in/partof the room etc.). This ontological distinction isn't really
important (it's a task-dependent question), and shouldn't distract the
debate -- what is important is that I have the components available in
the first place (ie. a representation of what it *means* to be a "container"
or a "point location") to be able to build either of these models as needed.

                - Pete
----end quote----

     Yeah, and I'd also emphasize the _conversion_ between the two
treatments of room, and the fundamentally related issue of the
particular _approximation_ involved in both representations.  A room
is not _really_ a point nor is it _really_ a container; it is useful
to think of it both ways, and in both cases certain (purpose-irrelevant)
information is deliberately suppressed and disregarded.  This is at the
heart of the Knowledge Sharing problem (or semantic database integration
for that matter).

                          Yours truly,   Fritz Lehmann
GRANDAI Software, 4282 Sandburg Way, Irvine, CA 92715, U.S.A.
Tel:(714)-733-0566  Fax:(714)-733-0506