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?

Sean