Black magic: Interdependence prevents principled parameter setting, self adapting costs too much computation

Abstract

The No Free Lunch theorem shows that the best algorithm for a particular problem is one tuned to that problem. Evolutionary Computation (EC) has many parameters to tune. These are usually fixed by hand, more by art than science. A poor choice of any of these can result in unsatisfactory performance. Self-adapting "parameterless" EC aims to avoid this guesswork. However, those efforts have focussed on one or another attribute, never all of them simultaneously. This paper demonstrates that such piecewise attempts are doomed to failure, because the customizable features are so interdependent. To self-adapt one particular attribute (or even a few) while guessing the others still lets unlucky guesses wreak havoc. This paper gives concrete examples of how, in a coevolving population of Backgammon strategies, both EC-specific and problem-specific attributes are so heavily interdependent that they give rise to bizarre side-effects. Even a fully "parameterless" algorithm adjusting all attributes may not be a solution because it vastly enlarges the search space, making EC even more computationally demanding. Will the human virtuoso remain indispensable