English

Frog model on $\mathbb{Z}$ with random survival parameter

Probability 2025-12-04 v2

Abstract

We study the frog model on Z \mathbb{Z} with geometric lifetimes, introducing a random survival parameter. Active and inactive particles are placed at the vertices of Z \mathbb{Z} . The lifetime of each active particle follows a geometric random variable with parameter 1p 1-p , where p p is randomly sampled from a distribution π \pi . Each active particle performs a simple random walk on Z \mathbb{Z} until it dies, activating any inactive particles it encounters along its path. In contrast to the usual case where p p is fixed, we show that there exist non-trivial distributions π \pi for which the model survives with positive probability. More specifically, for πBeta(α,β)\pi\sim Beta(\alpha,\beta), we establish the existence of a critical value β=0.5 \beta=0.5 , that separates almost sure extinction from survival with positive probability. Furthermore, we show that the model is recurrent whenever it survives with positive probability.

Keywords

Cite

@article{arxiv.2503.09766,
  title  = {Frog model on $\mathbb{Z}$ with random survival parameter},
  author = {Gustavo O. de Carvalho and Fábio P. Machado},
  journal= {arXiv preprint arXiv:2503.09766},
  year   = {2025}
}

Comments

17 pages, 1 figure

R2 v1 2026-06-28T22:18:09.626Z