Implementation Diary - Feb 25, 2009

I have been struggling with making Crackpot work with Logistics Domain. One recent observation here: This is the plot of number of costs in one run of the planner in Logistics Domain. As we can see there is a jump in number of costs suddenly from 10 to 200 within iterations from 175 to 300. The number of costs however always stays within 300, in 2000 iterations.

What is the cause of this sudden jump in number of costs? After investigation I found several costs fixed at that time were goal costs. For goals costs, we have only one heuristic that adds action into plan: addAction. There was one goal "Package 6 should be in depot 1b" and there was one action that pushed Package 6 to depot 1a near 278 time point. It seems actions were added one after another, but all not after 278, but before 278, which did not do anything to improve the cost of goal.