Problem solving and reasoning

The following iterative steps occur in typical blackboard solving activities:

1. A knowledge source makes a change to a blackboard object.
2. Each knowledge source indicates the contribution it can make to the new solution state -- either dynamically or a priori based.
3. A scheduler decides a focus of attention.

3
1. A control module prepares the focus of attention for execution:
   1. If the focus of attention is a knowledge source -- a blackboard object is chosen to serve as its context (knowledge centred scheduling).
   2. If the focus of attention is a blackboard object -- a knowledge source to process that object is chosen and instantiated with the object as its context (event centred scheduling).
   3. If both a blackboard object and a knowledge source are the focus of attention an instance of the knowledge source is made ready for execution with the object as its context.

4
1. The problem solving process continues until a knowledge source has indicated that it should stop:
   1. either an acceptable solution has been found, or
   2. lack of knowledge or data prohibits further action.