Doug, (01)
Thanks for the clarifications. (02)
> Cyc has a dozens of "rule macro predicates", which are predicates
> which provide a compact way of stating a rule. When commonly used rule
> patterns were discovered, RMPs were created for them and efficient code
> was written for executing the rule. The timing for reasoning using such
> modules is known or calculable. Such modules are not considered
> separate inference engines, but are called by the inference engine if
> a statement using the RMP (i.e., an encoded rule) is to be used in
> reasoning. (03)
That is a useful extension. Those rule patterns resemble the kinds
of "design patterns" that are used in software development. All major
programming languages are undecidable, but programmers have found
ways of using them efficiently. In effect, they use design patterns,
structures, and methodologies that show them how to use a very powerful
language in predictably efficient ways. (04)
> The basic inference engine is always used, the special reasoning routines
> are preferentially used if and when applicable. The Cyc reasoner also
> allows the user to limit the use of certain types of rules & to specify
> maximum reasoning depth, time, number of answers, and a number of other
> inference parameters. (05)
Those points reinforce my claim that there are many ways of using
a highly expressive language while (a) providing good performance,
(b) distinguishing easy problems from hard problems *before* attempting
to solve them, and (c) calculating and guaranteeing a required response
time when such guarantees are necessary. (06)
As I have said many times before, restricting the expressive power
of a logic cannot improve performance on any problem. Its only
effect is to make some kinds of problems impossible to state. (07)
John (08)
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