But, how do I do that? I mean, where do I check (in the code) that the individual generated does not fulfill the requirement of appearing every node at least once? Thanks a lot. 2014-02-24 19:56 GMT+01:00 Xiaomeng Ye <[log in to unmask]>: > Or you can simply discard any non-conformed individuals, during any > process (initialization, breeding). And keep generating new individuals > until your population is filled with the individuals conforming to this > rule. > > > On Mon, Feb 24, 2014 at 1:13 PM, Sean Luke <[log in to unmask]> wrote: > >> Francisco, ECJ can't do this by default: and I really have no idea how to >> require this constraint. You'll have to either enforce this rule in the >> tree builder algorithm and/or the crossover mutation operators. >> Alternatively you can assess the fitness of non-confirming individuals as >> very low. >> >> Sean >> >> On Feb 24, 2014, at 6:57 AM, Francisco Lopez de la Franca < >> [log in to unmask]> wrote: >> >> > Hello. >> > >> > I am new in ECJ. I'm going to use ECJ to find the solution of a second >> degree equation, that is, x=(-b+sqrt(b^2-4ac))/(2a). >> > I've implemented as FunctionSet the following nodes: add, sub, sqrt, >> square, mul, div, neg, a, b, c, 2 and 4. >> > I've followed the instructions described both in the tutorial4 in the >> documentations provided with ECJ and the one in the ECJ manual. >> > >> > What I need and donot find the way, is to force to appear in the result >> tree the nodes: a, b, c, 2, 4, -, +, sqrt, square, div and mul. That is, to >> specify in some manner that the nodes must appear at least once. Moreover, >> I'd like to know if it is possible to set that one node must appear a >> number of times in the solution. >> > >> > I hope to have explained well. >> > >> > Thank you very much in advance. >> > >> > Regards. >> > >