Sean, Any progress? I have, in the meantime, written a hardcoded 1+1 ES that does strict hillclimbing. It works as expected (although with unexpected results). Cheers, Steve On Sep 18, 2005, at 3:49 PM, Sean Luke wrote: > Hi Steve. If your information is correct, it looks to me that the > problem is with QuickSort not being a stable sort. ECJ's ES library > first sorts the population based on fitness, then uses the first > lambda > individuals in the population array as the new parent pool. > Because it > uses QuickSort, equal individuals do not necessarily sort the same way > in the pool. > > ECJ's minimum version of Java is now 1.2, meaning we can probably toss > out our QuickSort class and use java.util.List's sort routines, > including stable sorts based on MergeSort. It'll take us a few days, > but let us see if we can get an upgraded version of at least the ES > package for you fairly soon. > > Sean