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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


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David F. Barrero
Departamento de Automática
Universidad de Alcalá

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