School Seminars and Colloquia

The Evolution of Networks of Competing Boolean Nodes

Mathematical Physics Seminar

by Professor Kevin Bassler

Institution: Dept of Physics, University of Houston
Date: Mon 20th April 2009
Time: 1:00 PM
Location: Room 316, Alice Hoy Building, The University of Melbourne

Abstract: Boolean networks were originally proposed as simple models of genetic regulatory networks and have since been applied to a variety of other physical, social, and economic systems. They consist of a directed graph with nodes that have binary output states that are heterogeneous functions of the binary input they receive. Each node receives input only from the nodes connected to it by the in-links of the graph. Depending on the functions of the nodes, Boolean networks have two phases of dynamical behavior, fixed and "chaotic", and a continuous transition between the two phases.

The talk will discuss the evolution of Boolean networks that occurs when the nodes compete against each other in a fustrated use of a limited resource. This dynamics causes the network to evolve to a critical state at the boundary of the two dynamical phases. Using computer simulations and group theoretic arguments, it will be shown that, for large networks, the dynamics is highly symmetrical and results in the evolution of canalized networks. Canalization is a form of network robustness thought to be important for developmental biological systems. While for finite size networks, it will be shown that the symmetry of the evolutionary dynamics is broken and the network evolves to be input inverting rather than canalized.

For More Information: for further information please contact Iwan Jensen on email