Figure 10.4 The two flavors of parallelization. In sectioning (top), one task is
split into different independent subtasks that run at once and are combined. In
voting (bottom), the same task is run several times and the answers are
polled. The aggregation step (in accent) is the point of each: sectioning assembles parts
that must not secretly overlap, voting counts agreement to harden a high-stakes verdict.
Both fan out in code and rejoin in code; both bill once per branch.
