I think Orchard, Bob wrote:
>
> 2. another problem is that one starts trying to think about things
> like: should only rule 2 fire if (a b c) and (d e f)
> exist. Well in general this is impossible to enforce.
> Rules fire (or at least go on the agenda with a chance to
> be fired) when their patterns match. The facts don't
> always appear at the 'same time' in many systems. So in general
> you can't hold rule-1 from firing when (a b c) is asserted. How
> do you decide how long to wait? If the facts (a b c) and (d e f)
> are asserted at the same time should you get different behaviour
> than if they are asserted 2 minutes apart. Why? How to explain this
> to users?
I actually had the thought that there could also be -abstract- rules,
which would never be placed on the agenda; defqueries are already a
kind of "abstract rule." I don't know if this is just too cute, or if
it's a useful idea. Anyway, abstract rules would serve as "base rules"
for a family of other rules that extended them. Therefore they would
allow you to create the rule-2-only behaviour.
---------------------------------------------------------
Ernest Friedman-Hill
Distributed Systems Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
Org. 8920, MS 9012 [EMAIL PROTECTED]
PO Box 969 http://herzberg.ca.sandia.gov
Livermore, CA 94550
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