Events and modules in reaction systems

Reaction systems are a formal model of interactions between biochemical reactions. They are based on the observation that two basic mechanisms behind the functioning of biochemical reactions are facilitation and inhibition. In this paper we continue the investigation of reaction systems, and in particular we introduce the notion of a module, and then we investigate the formation and evolution of modules. Among others we prove that reaction systems can be viewed as self-organizing systems, where the organizing goal is to ensure a specific property of the set of all modules (of a state of a process).