Asymptotic shape conjecture for the contact process in an evolving random environment

From papers

Let (C,B)(\mathbf{C},\mathbf{B}) be a contact process in an evolving random environment (CPERE) on the dd-dimensional integer lattice, with infection rate λ>0\lambda>0 and recovery rate r>0r>0. Assume that B\mathbf{B} satisfies Assumption~, that θ(λ,r,{0},)>0\theta(\lambda,r,\{\mathbf{0}\},\emptyset)>0, and that there are constants C1,C2,M>0C_1,C_2,M>0 satisfying

\mathdsP(tτ<)C1exp(C2t),\mathds{P}(t\leq \tau<\infty)\leq C_1\exp(-C_2t), \mathdsP(xHMx1+t,τ=)C1exp(C2t),\mathds{P}(x\notin \mathbf{H}_{M\lVert x\rVert_1+t},\tau=\infty)\leq C_1\exp(-C_2t), \mathdsP(xKMx1+t,τ=)C1exp(C2t).\mathds{P}(x\notin \mathbf{K}_{M\lVert x\rVert_1+t},\tau=\infty)\leq C_1\exp(-C_2t).

Here τ\tau is the extinction time, Ht\mathbf{H}_t is the set of vertices infected by time tt, and Kt\mathbf{K}_t is the permanently coupled region; write Ht=Ht+[12,12]d\mathbf{H}'_t=\mathbf{H}_t+[-\tfrac12,\tfrac12]^d and Kt=Kt+[12,12]d\mathbf{K}'_t=\mathbf{K}_t+[-\tfrac12,\tfrac12]^d.

Asymptotic shape conjecture. There exists a bounded convex set U\mathdsRdU\subset\mathds{R}^d such that, for every ε>0\varepsilon>0,

\mathdsP(s0: t(1ε)U(KtHt)Htt(1+ε)U tsτ=)=1.\mathds{P}\left(\exists s\geq0:\ t(1-\varepsilon)U\subset(\mathbf{K}'_t\cap\mathbf{H}'_t)\subset\mathbf{H}'_t\subset t(1+\varepsilon)U\ \forall t\geq s\mathrel{\Big|}\tau=\infty\right)=1.

This is the expected asymptotic shape theorem for the CPERE: conditional on survival, the infected region and its permanently coupled core should grow with a deterministic convex shape. Analogous results are known for contact processes in static random environments and for contact processes with ageing, while this formulation remains conjectural here.

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Sources & referencesView supporting material

Primary source

Marco Seiler and Anja Sturm, “Contact process in an evolving random environment”, arXiv:2203.16270 (2023).

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