## ECJ-INTEREST-L@LISTSERV.GMU.EDU

 Options: Use Monospaced Font Show Text Part by Default Show All Mail Headers Message: [<< First] [< Prev] [Next >] [Last >>] Topic: [<< First] [< Prev] [Next >] [Last >>] Author: [<< First] [< Prev] [Next >] [Last >>]

 Subject: How to implement a gp problem with unknown number of variables From: "Buijs, J.C.A.M." <[log in to unmask]> Reply To: ECJ Evolutionary Computation Toolkit <[log in to unmask]> Date: Wed, 5 Oct 2011 23:43:07 +0200 Content-Type: text/plain Parts/Attachments: text/plain (17 lines)
```Hi all,

I'm afraid I have quite a newbie question. I have followed the tutorials, especially tutorial 4, but I'm still overwhelmed by the functionality of ECJ. Therefore I would like your advise on the following:

I have a problem that I can represent as a tree and would like to solve using a genetic algorithm. The number of function nodes is limited (lets say they are the arithmetic operators of tutorial 4). The leaves can be instances of a limited alphabet (say A,B,C) that is different for each problem instance.
A solution I'm looking for could for instance be '+ A (- B (* C A )'.

When I look at the type of problem of tutorial 4 then this is solving a formula with 2 variables and 3 operators. In my problem I have an unknown number of variables. So my question is how do I go about solving this? I can't create classes beforehand since I don't know the (size of the) alphabet beforehand. I could create one class (say AlphabetInstance) but how do I initialize each instance with a value from the alphabet while not breaking the ECJ framework guidelines.

So, in short, my question is how to model a problem with an unknown number of variables and instances of these variables.

Thank you in advance for any replies.

Joos Buijs
PhD Student
Eindhoven University of Technology
```