The Control
control is event-driven, i.e. the KS respond opportunistically to changes in the BL
there may be a specific control module, or some specific KS, which monitor changes on the BL and decide what action to take next
the information utilized by the control modules can be stored in the BL or in separate data structures
the sequence of KS activation is dynamically identified
each operation on the BL constitutes an event, which, together with the presence of other specific information in the BL, can trigger (satisfy the condition of) one or more KS. Each triggering is recorded in a KSAR (KS activation record). A queue of KSAR
at each step a single KSAR is selected for execution of the corresponding action
the solution process proceeds one step at the time
scheduling of KSAR may conform to several criteria
a focus of attention mechanism can be used in order to identify the next thing to work upon