Topology and local geometry of the Eden model

TL;DR

This paper investigates the topology and local geometry of the Eden model's growth structures, providing asymptotic bounds for Betti numbers and exploring their geometric properties through computational experiments.

Contribution

It establishes bounds for Betti number growth in the Eden model and analyzes topological features using computational methods, advancing understanding of its geometric complexity.

Findings

Betti numbers grow between perimeter growth rates

Topological features analyzed via persistent homology

Computational experiments reveal shape distributions of holes

Abstract

The Eden cell growth model is a simple discrete stochastic process which produces a "blob" in $\mathbb{R}^d$: start with one cube in the regular grid, and at each time step add a neighboring cube uniformly at random. This process has been used as a model for the growth of aggregations, tumors, and bacterial colonies and the healing of wounds, among other natural processes. Here, we study the topology and local geometry of the resulting structure, establishing asymptotic bounds for Betti numbers. Our main result is that the Betti numbers grow at a rate between the conjectured rate of growth of the site perimeter and the actual rate of growth of the site perimeter. We also present the results of computational experiments on finer aspects of the geometry and topology, such as persistent homology and the distribution of shapes of holes.