flex Expert System Toolkit - LPIS

3. Forward Chaining 37
The Rule Agenda
The rule agenda determines the rules currently available to the inference
engine during forward chaining (initially specified by a ruleset). It might
include all of the rules in the system, or only a subset.
The rule agenda may contain duplicates, and there are no restrictions
whatsoever on which names can go into the list.
After a rule has been selected and fired, the rule agenda may be updated,
and it is this revised agenda that the inference engine uses as the basis for
the next cycle.
Setting The Initial Rule Agenda
The initial rule agenda is the set of rules from which the forward chaining
engine makes its first selection. The initial rule agenda may be specified as
containing all rules, a list of rules or a rule group.
The only mandatory part of a given ruleset is the definition of the initial
rule agenda.
ruleset everything
contains all rules .
This KSL sentence sets the initial rule agenda to contain all the rules
currently defined.
Selecting Rules
A vital part of any engine, whether forward or backward chaining, is the
method by which rules are selected. flex provides three built-in methods for
selecting rules:
First come first served
Conflict resolution
Conflict resolution with a threshold.
In addition, there is a facility for hooking in user-defined selection
algorithms.
flex toolkit