flex Expert System Toolkit - LPIS

3. Forward Chaining 34
A Simple Model
All production rule systems are based upon the same, very simple model.
This is illustrated by the following flowchart.
START
Choose a
rule ?
No
STOP
Yes
Yes
Fire the
rule ?
No
FAIL
The basic cycle of all forward chaining engines involves the selection of a
rule (checking the IF part), followed by the firing of that rule (executing the
THEN part).
When implemented as a Prolog program, the individual parts of the engine
can either succeed or fail, as indicated by the alternative yes and no
branches.
The Implemented Model
Forward chaining in flex is an elaboration of the simple model given above.
The implemented model is closer to the following flowchart:
flex toolkit