  The recently measured yeast transcriptional network is analyzed in terms of
simplified Boolean network models, with the aim of determining feasible rule
structures, given the requirement of stable solutions of the generated Boolean
networks. We find that for ensembles of generated models, those with canalyzing
Boolean rules are remarkably stable, whereas those with random Boolean rules
are only marginally stable. Furthermore, substantial parts of the generated
networks are frozen, in the sense that they reach the same state regardless of
initial state. Thus, our ensemble approach suggests that the yeast network
shows highly ordered dynamics.
