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reported above  is still fairly simple  and is successful without relying on domain dependent We take this as evidence that the effectiveness of our approach is not due heuristics to cleverness in the construction analysis and prioritization techniques but due to the effectiveness of the SWO cycle at identifying and responding to whatever elements of the problem happen to be causing difficulty in the local region of the search It is also instructive to compare the results of a good heuristic ordering  with the se quence derived by SWO A good heuristic for this scheduling domain  and the one that is used to initially populate the priority sequence is to sort the tasks by the number of production lines on which a task could be feasibly assigned in an empty schedule  A task that can be scheduled on many lines is likely to be easier to schedule than one that is compatible with only a small number of lines  and should therefore be expected to need a lower priority The top graph in Figure shows the sequence of tasks as determined by this heuristic  The lower graph illustrates the changes in priority of these tasks  after swo has run for fourteen iterations  enough to improve the solution derived from the sequence to within percent of the best known solution As the figure illustrates the heuristic is generally accurate  but swo has had to move some tasks that are compatible with most of the production lines to positions of relatively high priority  reflecting the fact that contrary to the heuristic  these tasks turned out to be relatively difficult to schedule well Other tasks that are compatible with only a few pro duction lines are actually easy to schedule well  and have moved to relatively low priorities