Applying the first five rules to the schedule in Figure 20.10 produces the precedence graph
shown in Figure 20.12(a). Applying rule 6(a), we add the edges T11→ T12 and T11→ T13, both labeled 0; applying rule 6(b), we add the edges T11→ T13 (which is already present) and T12→ T13, again both labeled 0. The final graph is shown in Figure 20.12(b).