Critique: Failure Handling in a Design Expert System
Brown
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Using a minimum of knowledge available locally
about the global state of the system is motivated by human memory
limitations. Why limit the system in the same way a person is limited?
Shouldn't these systems help people overcome their limitations?
I see several possible reasons. It is far easier to access this
information from a local point of view. This is apparent from the
now long-lasting popularity of object oriented styles of
design/programming.
It is easier to facilitate communication between components if
messages are only passed between incident components in the hierarchy.
By only considering locally available information, the changes, if any,
resulting from failure recovery are more likely to stay local.
Minimizing the changes and scope thereof in redesign seems to be a
fairly accepted heuristic.
Of course, the very best point I could think of was already
offered in the reading. That is, the belief that much can be learned
about the behavior of agents in a design system by considering it a
person in a design team.
I was surprised when MOLGEN was not mentioned in reference to
means-ends analysis to handle unusual failures not covered in
the context of a routine design task.
It seems using "knowledge of situation-action associations" in a
Failure Handler is just a fancy way of saying forward chaining.
Is there a great cause for distancing this discussion of failure
handling from that of general AI techniques such as forward chaining?
Is it possible that I may be reading too far into a certain choice
of words? Speaking of choosing words, finally some humor in the readings,
that I understood anyway. The "+++" notation did confuse me for a
moment though.
The section on Redesigners and the limited number of basic strategies
used during redesign seems to serve as a prelude to Klein's whole take on
conflict resolution. That conflict resolution, which redesign attempts to
do, expertise is general and applicable across many domains.
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Brown, Failure Handling
D. C. Brown, Failure Handling in a Design Expert System.
Computer-Aided Design, Butterworths, Nov. 1985.
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