873913.fig.019a
(a)
873913.fig.019b
(b)
873913.fig.019c
(c)
Figure 19: The effort for hierarchical search in hierarchies with one abstract level, two abstract levels, and three abstract levels. We show in what proportion the main effort, the SG effort, and the refinement effort contribute to the total effort. The gray part at the bottom of a data bar represents the main effort. The dark part in the middle is the SG effort. The white part at the top is the refinement effort.