ar X iv : n lin / 0 61 10 49 v 1 [ nl in . C G ] 2 6 N ov 2 00 6 Local cause of coherence in Boolean networks

We performed a numerical study on random Boolean networks with power-law rank outdegree distributions to find local structural cause for the emergence of high or low degree of coherence in binary state variables. The degree of randomness and coherence of the binary sequence are measured by entropy and mutual information, depending on local structure that consists of a node with a highly connected, called hub and its upstream nodes, and types of Boolean functions for the nodes. With a large number of output connections from a hub, the effects of Boolean function on the hub are more prominent. The local structures that give larger entropy tend to give rise to larger mutual information. Based on the numerical results and structural conditions we derived a time-independent transmission characteristic function of state variables for the local structures. We obtained good relationships between the numerical and analytical results, which indicate that dynamical properties from the whole networks can be inferred from the differences in the local structures. keywords: Boolean networks; power-law; coherence; mutual information; entropy; transcriptional regulatory networks Correspoding author: [email protected] Also at: Bioalgorithm Project, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology