On May 5, 2007, at 12:36 AM, Matthew Walker wrote:

> I'm *very* new to ECJ, so my apologies if I have done something  
> stupid.  I would, however, very much appreciate someone telling me  
> where I've gone wrong!
> I have run the parity examples provided with ECJ and I'm confused  
> with the results.  I have tried to reproduce some of the  
> experiments in Koza's second book.  My expectation was that I could  
> use the parity examples provided with ECJ to get similar results to  
> chapter 6 of GPII which generally concludes that the use of ADFs is  
> a good thing for this domain.
> ...
> So, to summarize, Standard GP scored 32.4% while GP with ADFs  
> scored 0.6%.  From Koza's second book on GP (page 181), this was  
> not what I expected to get.  I expected GP with ADFs to outperform  
> standard GP on this problem domain.  I sat around scratching my  
> head trying to work out what I had done wrong, however nothing but  
> hair came out ;o)

Hi Matt.  This is the first time that this bug [if it is one] has  
been reported and no, you're not necessarily doing something stupid.   
I'm not sure what the problem is, but there are several possibilities:

	- A bug in the ADF code (possible)
	- A bug in the parity problem example (less likely but possible)
	- Errors in Koza's text

There have been some significant errors in Koza's text on certain  
problem domains, so it's a definite possibility.  What we need is a  
third implementation to verify if it's ECJ doing this or not.  lil-gp  
anyone?  Or maybe open beagle?

As to memory: 16,000 is a big number for ECJ, which is fairly memory  
hungry.  What -Xmx and -Xms settings did you set on your VM, however?