Re: multiple inheritance
At 4:30 PM -0400 8/6/2000, Patrick Cassidy wrote:
>Certainly any multiple inheritance links used must be consistent,
>and anyone who uses them will have to check carefully for
>consistency. One of the important uses of multiple inheritance will
>be to allow aggregates of concepts which are useful for particular
>purposes. A manufacturer of pocketbooks, for instance, may want to
>create a class of "hide-bearing animals" which includes both
>alligators and cattle.
Well, this is not an example of multiple inheritance... Here there is
just a single class subsuming two different classes, no problems at
all...
>One might want to classify a "bayonet" as both a "cutting
>instrument" and a "weapon". These two categories would have many
>members which are not in common. Similarly, military watercraft may
>be categorized as both "watercraft" and "weapons systems".
OK.
>The same ends can be accomplished without multiple inheritance, but
>it will be more complicated. The point of an ontology is to create a
>compact and easily maintainable representation of knowledge, and
>multiple inheritance is a means to make the representation more
>compact then it would be with single inheritance.
>
> The other main reason for multiple inheritance is to make it easier to
>generate agreement on a standard upper ontology. In merging existing
>ontologies, it will probably be necessary for some groups to give up
>some features that they consider useful, but if using multiple inheritance
>can allow different *consistent* views to be include in the same
>ontology, it will ease the pain of transition and increase the likelihood
>of being able to create a standard that can be widely used.
I agree. Unfortunately, in many cases different views are only
apparently consistent. To recognize where the potential inconsistence
is, a certain depth of analysis is often needed (this is exactly the
point of the paper I wrote with Chris).
> Does anyone actually classify a castle under "bunch of bricks"? ;-)
Well, take a ruined castle: somebody with no archeological experience
may just take it as a bunch of bricks (I am not sure of the
appropriateness of the English word "bunch", however).
---------------------------------
Nicola Guarino
National Research Council phone: +39 O49 8295751
LADSEB-CNR fax: +39 O49 8295763
Corso Stati Uniti, 4 email: Nicola.Guarino@ladseb.pd.cnr.it
I-35127 Padova
Italy
http://www.ladseb.pd.cnr.it/infor/ontology/ontology.html
(***updated 2/6/2000***)