English

Random trees with local catastrophes: the Brownian case

Probability 2025-11-21 v2 Combinatorics

Abstract

We introduce and study a model of plane random trees generalizing the famous Bienaym\'e--Galton--Watson model but where births and deaths are locally correlated. More precisely, given a random variable (B,H)(B,H) with values in {1,2,3,}2\{1,2,3, \dots\}^2, given the state of the tree at some generation, the next generation is obtained (informally) by successively deleting BB individuals side-by-side and replacing them with HH new particles where the samplings are i.i.d. We prove that, in the critical case E[B]=E[H]\mathbb{E}[B]=\mathbb{E}[H], and under a third moment condition on BB and HH, the random trees coding the genealogy of the population model converges towards the Brownian Continuum Random Tree. Interestingly, our proof does not use the classical height process or the {\L}ukasiewicz exploration, but rather the stochastic flow point of view introduced by Bertoin and Le Gall.

Keywords

Cite

@article{arxiv.2401.06770,
  title  = {Random trees with local catastrophes: the Brownian case},
  author = {Ariane Carrance and Jérôme Casse and Nicolas Curien},
  journal= {arXiv preprint arXiv:2401.06770},
  year   = {2025}
}

Comments

Updated version with some corrected lemmas, 35 pages, 7 figures

R2 v1 2026-06-28T14:15:33.278Z