Serethos a écrit :
> Perhaps I consequently overlooks it but I can not find the parameter
> entry for mutation probability in GP Problems. What is the default
> and where is it defined?
>
it is not always defined (since Koza did not use mutation in his 1st 
book). You first have to create a breeder pipeline with a supplentary 
source, then bind it to a mutation pipeline, then use the standard 
"prob" attribute:

pop.subpop.0.species.pipe.num-sources = 3
pop.subpop.0.species.pipe.source.0 = ec.gp.koza.CrossoverPipeline
pop.subpop.0.species.pipe.source.0.prob = 0.9
pop.subpop.0.species.pipe.source.1 = ec.gp.koza.MutationPipeline
pop.subpop.0.species.pipe.source.1.prob = 0.05
pop.subpop.0.species.pipe.source.2 = ec.breed.ReproductionPipeline
pop.subpop.0.species.pipe.source.2.prob = 0.05

-- 
Denis Robilliard
Laboratoire d'Informatique du Littoral
50 rue Ferdinand Buisson
62100 CALAIS