Dear all,

I'm using a constrained-based GP to evolve functions for a problem I have. My individual must return a double. However, in my problem there is not terminal node that returns a double. If I don't use a terminal that returns a double, I get the following warning (followed by an error).

A GPNodeBuilder has been requested at least once to generate a one-node tree with a return value type-compatable with a certain type; but there is no TERMINAL which is type-compatable in this way.  As a result, the algorithm was forced to use a NON-TERMINAL, making the tree larger than requested, and exposing more child slots to fill, which if not carefully considered, could recursively repeat this problem and eventually fill all memory.

ONCE-ONLY WARNING:

class ec.gp.koza.FullBuilder can't find a terminal type-compatable with number
java.lang.StackOverflowError
at ec.gp.GPNodeBuilder.warnAboutNoTerminalWithType(GPNodeBuilder.java:238)
at ec.gp.koza.KozaBuilder.fullNode(KozaBuilder.java:117)
....
recursively
...

I would like to understand at this point, since I have a lot of non-terminal nodes that return a double. Is there a way to avoid this problem even without using a terminal node that returns a double? If ECJ doesn't present this problem if I have a terminal node returning a double (ECJ chooses this terminal node as root), it could chose one of many non-terminal nodes as the root node. Is there any way to do that?

Best,
Márcio

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Prof. Dr. Márcio Porto Basgalupp
Instituto de Ciência e Tecnologia (ICT)
Universidade Federal de São Paulo (UNIFESP)
Tel: +55 12 3924-9500 (r: 9762)