Re: Contexts and views
macgregor@isi.edu (Robert MacGregor)
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Date: Wed, 31 May 1995 17:11:46 -0800
To: sowa@west.poly.edu (John F. Sowa), cg@cs.umn.edu, kr-advisory@isi.edu,
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From: macgregor@isi.edu (Robert MacGregor)
Subject: Re: Contexts and views
Cc: fikes@sumex-aim.stanford.edu, mrg@cs.stanford.edu, vishal@cs.stanford.edu
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Our notion of contexts would seem to be rather different than John's.
In our system, its not possible to look inside of a context from
outside. Instead, to "see" the facts, definitions, etc. in a context,
you must be in it, or in one of its children. This is in accord
with normal scoping rules.
Also, we support
multiple inheritance -- our context hierarchies are not limited
to trees. We have quite a few users (mostly in the NL domain)
who use the multiple inheritance feature. One way to reason
with two different views/contexts is to create a new context
that inherits both of them.
We have also identified (but not yet implemented) a need for
an export feature (lifting). Often, one would like to reference some
of the objects in a context without inheriting that context.
That provides a second means for interviewing the contents
of a context without being in or below it.
- Bob
Robert M. MacGregor macgregor@isi.edu
USC/ISI, 4676 Admiralty Way, Marina del Rey, CA 90292 (310) 822-1511