Formal Framework for Cost Analysis Based on Process Algebra

Several formal systems have been proposed for reasoning about concurrent systems. The Algebra of Communicating Processes (ACP) is proposed by J. A. Bergstra and J. W. Klop, and an algebraic system for such reasoning. In such formal systems, the equivalence between processes is the fundamental relation for reasoning, and several kinds of equivalence have been investigated in the process algebras. These equivalence relations are based on behavior of processes. Recently, the computational cost in execution of processes is considered to be one of the important factors in concurrent systems and is beginning to interest to us. For example, the denial-of-service attacks are related to it closely. We developed a formal system for reasoning about computational costs of concurrent systems in the previous works, based on the Milner’s pi-calculus. In this paper, we investigate another system based on ACP.