Thanks for your fast and valuable comments. I increased the Artificial Ant timestep to 600, as you suggested, and it seems to work :). It might be of interest to someone in the list the results of my experiments, so I left them here. ANT --- Koza I (p202): Imin=450k, SR=7% ECJ: Imin=666K, SR=11% Notes: 100 runs, M=500, timestep set to 600 6-MULTIPLEXER ------------- Koza I (p196): Imin=245k, SR=75% ECJ: Imin=427k, SR=70% Notes: 50 runs, M=500, G=200, fitness proportionale selection used instead of tournament SIMPLE REGRESSION ----------------- Koza I (p203): Imin=162k, SR=34% ECJ: Imin=188k, SR=30% Notes: 100 runs, M=500, ECJ default parameters EVEN-5 PARITY ------------- Koza I (p543): SR=0% ECJ: Imin=3.38E7, SR=4% Notes: 50 runs, M=4000 EVEN-5 PARITY WITH ADF ---------------------- Koza I (p544): Imin=152k, SR=5% ECJ: SR=0% Notes: 100 runs, M=4000 Best regards, David Sean Luke escribió: > There is always the definite possibility of a bug in ECJ: for example, I > just routed out a long-standing one in Lawnmower recently (check CVS). > But another reason may be that Koza-I and Koza-II'ss results have proven > historically difficult to reproduce. There are a number of reasons for > this, but here are two: the random number generator used in Koza-I and > Koza-II was troublingly non-random; and certain variables are not as > you'd expect in print. For example, though Koza-I says 400 timesteps > for Artificial Ant, in fact it's believed he used 600. So much > subsequenty work used 400 timesteps as a result that that's the default > for both ECJ and lil-gp. You an change it to 600 and see what's up. > There are other explanations for differences which have been offered > which I don't want to get into here. > > So: if we can nail down a bug, I'd love to find out. But be prepared > for the probability that it's Koza-I and not ECJ. One way to check for > the possibility of an ECJ bug in certain problems is to run lil-gp and > see which one it more or less agrees with. Let me know what you get. > > Sean > > On Oct 27, 2009, at 5:37 PM, David F. Barrero wrote: > >> Dear all, >> >> I am trying to reproduce Koza's performance curves for some typical GP >> problems implemented in ECJ, but I had a limited success. Some problems >> such as simple regression have similar performance curves compared with >> the ones shown in Koza I, while others (for instance, Santa Fe trail or >> even 5 parity with ADFs) yields very different curves. >> >> In theory, should ECJ examples generate the same performance curves than >> those shown in Koza I/II?. >> >> >> Thanks in advance, >> >> David -- David F. Barrero Departamento de Automática Universidad de Alcalá Tlf: (34) 91-885-69-20 Web : http://atc1.aut.uah.es/~david/ Jabber/GTalk: [log in to unmask] Skype: dfbarrero Escuela Politécnica Departamento de Automática Despacho E-236 Ctra. Madrid-Barcelona km 31,600 28871 Alcalá de Henares. Madrid --