You can download a free guide to genetic programming here.http://www.gp-field-guide.org.uk/ This example aims to reconstruct a simple mathematic function,which can been refined in def examplefun(x, y). I have given x * x + x + 2 * y + 1 to it. Nodes in a tree can be classified to three kinds:function,variable and constant, so I have built three wrappers:funwrapper,variable and constant. The fitnes