918252.fig.0021a
(a) and are active
918252.fig.0021b
(b) and are active
918252.fig.0021c
(c) and are active
918252.fig.0021d
(d) and are active
Figure 21: cannot be fully unit-disk covered by two opposite polar nodes from , even all the nodes in are active. The shaded regions indicate the uncovered regions.