

![0_image_0.png](0_image_0.png) 
(b)

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plans. None of the other approaches is able to solve more than **four problems.**7 AltAltpis able to scale up without any difficulty to problems involving 30 balls. Furthermore, AltAltp returns better plans than LPG.

Elevator: **In Figure 9(b), we compare** AltAltp**to STAN, Blackbox and LPG in the Elevator**
domain (Miconic Strips) (Bacchus, 2001).8 AltAltp **approached the quality of the solutions**
produced by the optimal approaches (e.g. Blackbox and STAN). Notice that Blackbox can only solve around half of the problems solved by AltAltp**in this domain.**
Scheduling: **Results from the Scheduling domain are shown in Figure 10. Only Blackbox**
and STAN are considered for comparison.9 AltAltp**seems to reasonably approximate the**
optimal parallel plans for many problems (around 50 of them), but does produce significantly suboptimal plans for some. However, it is again able to solve **more problems than the other**
two approaches and in a fraction of the time.

Logistics: **The plots corresponding to the Logistics domain from Bacchus (2001) are shown**
in Figure 11.10 **For some of the most difficult problems** AltAltp **outputs lower quality** solutions than the optimal approaches. However, only AltAltp **and LPG are able to scale**
up to more complex problems, and we can easily see that AltAltp **provides better quality** solutions than LPG. AltAltp **also seems to be more efficient than any of the other approaches.**