Network formation by contact arrested propagation

We propose here a network growth model which we term Contact Arrested Propagation (CAP). One representation of the CAP model comprises a set of two-dimensional line segments on a lattice, propagating independently at constant speed in both directions until they collide. The generic form of the model extends to arbitrary networks, and, in particular, to three-dimensional lattices, where it may be realised as a set of expanding planes, halted upon intersection. The model is implemented as a simple and completely background independent substitution system. trict attention to one-, two- and three-dimensional background lattices and investigate how CAP networks are influenced by lattice connectivity, spatial dimension, system size and initial conditions. Certain scaling properties exhibit little sensitivity to the particular lattice connectivity but change significantly with lattice dimension, indicating universality. Suggested applications of the model include various fracturing and fragmentation processes, and we expect that CAP may find many other uses, due to its simplicity, generality and ease of implementation.