Beating exhaustive search at its own game: revisiting evolutionary mastermind

The Mastermind puzzle consists in finding out a secret combination by playing others in the same search space and using the hints obtained as a response (which reveal how close the played combination is to the secret one) to produce new combinations and eventually the secret one. Despite having been researched for a number of years, there are still several open issues, such as finding a strategy to select the next combination to play that is able to consistently obtain good results, at any problem size, and also doing it in as little time as possible. In this paper we cast this as a constrained optimization problem, introducing a new fitness function for evolutionary algorithms that takes that fact into account, and compare it to other solutions (exhaustive/heuristic and evolutionary), finding that it is able to obtain the consistently good solutions, and in as little as 30% less time than previously published evolutionary algorithms [2].