Empirical Linkage Learning

Linkage learning techniques are a crucial part of many modern evolutionary methods dedicated to solving problems in discrete domains. Linkage information quality is decisive for the effectiveness of these methods. In this article, we point on two possible linkage inaccuracy types. The missing linkage that occurs when some gene dependencies remain undiscovered, and the false linkage that takes place when linkage identifies gene dependencies that do not exist. To the best of our knowledge, all linkage learning techniques proposed so far are based on predictions, which can commit both of the mistake types. We propose a different approach. Instead of using statistical measures, or evolving the linkage, we check which genes are dependent on one another employing disturbances and the local search. We prove that the proposed technique will never report any false linkage. Thus, the proposed linkage learning based on local optimization (3LO) may miss some linkage but will never report a false one. The main objective of this article is to show the potential brought by 3LO that is fundamentally different from other linkage learning techniques. Since the main disadvantage of the proposed technique is its computational cost, it does not seem suitable for some of the already known, effective evolutionary methods. To overcome this issue, we propose an evolutionary method that employs 3LO. The extensive experimental analysis performed on a large set of hard computational problems shows that the method using 3LO is found to be competitive with other state-of-the-art methods.