The addition of a neutral gene to a seed might seem, at first sight, the wrong thing to do as most of the times we are interested in creating efficient and parsimonious models. But one should look at this as modeling in progress as, for really complex phenomena, it is not uncommon to approximate a complex function progressively.
Thus, being able of introducing extra terms to your seed is a powerful modeling tool and APS 3.0 allows you to do that through the Change Seed window.
Here, by pressing the Add Neutral Gene button, you will see a neutral gene being added to your model. By doing this, you are giving the learning algorithm more room to play and, hopefully, a better, more complex program will evolve.
Automatic Problem Solver 3.0 also allows you to introduce neutral genes automatically by activating the Complexity Increase
Engine in the Settings Panel -> General Settings Tab.
Whenever you are using the Complexity Increase Engine of APS 3.0, you must fill the Generations Without Change box to set the period of time you think acceptable for evolution to occur without improvement in best fitness, after which
a mass extinction is created or a neutral gene (an extra term) is automatically added to
the evolving models; the Number of Tries box corresponds to the
number of consecutive evolutionary epochs (defined by the parameter
Generations Without Change) you will allow before a neutral gene is
introduced in all evolving models; in the Max. Complexity box you write the maximum number of terms (genes) you’ll allow in your model and no other terms will be introduced beyond this threshold.
As stated previously, the Complexity Increase Engine of APS 3.0 might be a very powerful modeling tool, especially for
Time Series Prediction, but you must be careful not to create excessively complex models for, most of the times, a greater complexity does not imply a greater efficiency.
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