Competitive displacement in the grass-bushes-trees process on a scale-free network

Source abstract

The grass-bushes-trees process is a two-type contact process in which the types face asymmetric birth mechanisms. Vertices of a graph can either be occupied by a tree, occupied by a bush, or empty (containing grass). The trees die with rate $1$ and give birth with rate $λ_{\mathcal T}$ on any neighbouring vertex (possibly taking the place of a bush). Bushes die with rate $1$ and give birth with rate $λ_{\mathcal B}$ on any empty neighbouring vertex; in particular, they are forbidden from taking the place of trees. We study this process on a power law random graph, namely the erased configuration model. We study which graph parameters lead to the possibility of coexistence versus the necessity of competitive displacement, i.e. joint metastability or fast extinction of the bushes.