  This is the first of two papers about the structure of Kauffman networks. In
this paper we define the relevant elements of random networks of automata,
following previous work by Flyvbjerg and Flyvbjerg and Kjaer, and we study
numerically their probability distribution in the chaotic phase and on the
critical line of the model. A simple approximate argument predicts that their
number scales as sqrt(N) on the critical line, while it is linear with N in the
chaotic phase and independent of system size in the frozen phase. This argument
is confirmed by numerical results. The study of the relevant elements gives
useful information about the properties of the attractors in critical networks,
where the pictures coming from either approximate computation methods or from
simulations are not very clear.
