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The following iterative steps occur in typical blackboard solving activities:
- A knowledge source makes a change to a blackboard object.
- Each knowledge source indicates the contribution it can make to the new
solution state -- either dynamically or a priori based.
- A scheduler decides a focus of attention.
3
- A control module prepares the focus of attention for execution:
- If the focus of attention is a knowledge source -- a blackboard object
is chosen to serve as its context (knowledge centred scheduling).
- 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).
- 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
- The problem solving process continues until a knowledge source has
indicated that it should stop:
- either an acceptable solution has been found, or
- lack of knowledge or data prohibits further action.
dave@cs.cf.ac.uk