Autonomous Boolean network regulation based on logic gates’ response characteristics

Abstract

Boolean networks (BNs) are nonlinear systems and each BN has a simple structure, thus it is easy to construct large networks. The BNs are becoming increasingly important as they have been widely used in many fields like random number generation, gene regulation, and reservoir computing. In recent years, autonomous Boolean networks (ABNs) have been proposed and realized by actual digital logic circuit. The BNs each have a clock or selection device to determine the update time of each node. Unlike BNs, ABNs have no device to control the update mechanism, and the update of each node is determined by response characteristics of the logic gate that make up the node, which leads to continuous and complicated outputs. Time series with different complexities including periodic and chaotic sequences can be generated by the ABNs, which is very meaningful in different applications.Research on the regulation of ABNs’ output is of big significance. Non-ideal response characteristics of the logic gates and time delay on the link are two major factors which can regulate the output state. Many studies focus on time delay on the link and indicate that the large delay inconsistency leads to complex outputs.In this paper, in order to study the regulation of ABNs’ output, it is demonstrated that the response characteristics of the logic gate can be continuously adjusted by the parameters in the ABNs’ equations. Then the effects of logic gates’ response characteristics on ABNs’ outputs are studied by simulation. The simulation results indicate that the ABNs’ outputs can transform between periodic and chaotic state with the change of logic gates’ response characteristics. Moreover, the interrelationship between logic gates’ response characteristics and propagation delays along the links is reinvestigated. The results show that the high complexity series space is extended by the fast logic gates’ response characteristics. Also the effects of different logic gates’ response characteristics on the ABNs’ output are compared, and the results indicate that node 2 has a good performance on the regulation of ABNs’ output while node 1 and node 3 show small effect on the ABNs’ output.It is concluded that the complexity of the ABNs’ output can be regulated by the logic gates’ response characteristics, and the high complexity series’ generation can be promoted by the fast logic gates’ response characteristics. This conclusion is conducive to the logic gates’ selection in random number generation, gene regulation, reservoir computing and other applications.