Problem decomposition using indirect reciprocity in evolved populations

Abstract

Evolutionary problem decomposition techniques divide a complex problem into simpler subproblems, evolve individuals to produce subcomponents that solve the subproblems, and then assemble the subcomponents to produce an overall solution. Ideally, these techniques would automatically decompose the problem and dynamically assemble the subcomponents to form the solution. However, although significant progress in automated problem decomposition has been made, most techniques explicitly assemble the complete solution as part of the fitness function. In this paper, we propose a digital-evolution technique that lays the groundwork for enabling individuals within the population to dynamically decompose a problem and assemble a solution. Specifically, our approach evolves specialists that produce some subcomponents of a problem, cooperate with others to receive different subcomponents, and then assemble the subcomponents to produce an overall solution. We first establish that this technique is able to evolve specialists that cooperate. We then demonstrate that it is more effective to use a generalist strategy, wherein organisms solve the entire problem themselves, on simple problems, but that a specialist strategy is better on complex problems. Finally, we show that our technique automatically selects a generalist or specialist strategy based on the complexity of the problem.