2025/05/28 by Benedikt Jahnel, Jahnel, Benedikt, Lukas Lüchtrath +3 · 1 citation
Physics and Astronomy · Mathematics · #Complex Network Analysis Techniques #Theoretical and Computational Physics #Stochastic processes and statistical mechanics
paper · pdf · doi:10.48550/arxiv.2505.22471
We propose a new perspective on the asymptotic regimes of fast and slow extinction in the contact process on locally converging sequences of sparse finite graphs. We characterise the phase boundary by the existence of a metastable density, which makes the study of the phase transition particularly amenable to local-convergence techniques. We use this approach to derive general conditions for the coincidence of the critical threshold with the survival/extinction threshold in the local limit. We further argue that the correct time scale to separate fast extinction from slow extinction in sparse graphs is, in general, the exponential scale, by showing that fast extinction may occur on stretched exponential time scales in sparse scale-free spatial networks. Together with the results of Nam, Nguyen and Sly (Trans. Am. Math. Soc. 375, 2022), our methods can be applied to deduce that the fast/slow threshold in sparse configuration models coincides with the survival/extinction threshold on the limiting Galton-Watson tree.