Uniform temporal trees

TL;DR

This paper introduces uniform temporal trees, a new class of random trees with decreasing edge labels, and analyzes their size, height, and degree distribution, revealing limit laws and asymptotic behaviors.

Contribution

The paper defines uniform temporal trees and their percolated variants, providing new theoretical results on their size distribution, height, and structural properties.

Findings

Size scaled by e^{np} converges to exponential(1)

Height scaled by np converges to e in probability

Trees exhibit similarities to uniform random recursive trees

Abstract

Motivated by the study of random temporal networks, we introduce a class of random trees that we coin \emph{uniform temporal trees}. A uniform temporal tree is obtained by assigning independent uniform $[0,1]$ labels to the edges of a rooted complete infinite $n$-ary tree and keeping only those vertices for which the path from the root to the vertex has decreasing edge labels. The $p$-percolated uniform temporal tree, denoted by $\mathcal{T}_{n,p}$, is obtained similarly, with the additional constraint that the edge labels on each path are all below $p$. We study several properties of these trees, including their size, height, the typical depth of a vertex, and degree distribution. In particular, we establish a limit law for the size of $\mathcal{T}_{n,p}$ which states that $\frac{|\mathcal{T}_{n,p}|}{e^{np}}$ converges in distribution to an $\exponential(1)$ random variable as $n \to \infty$. For the height $H_{n,p}$, we prove that $\frac{H_{n,p}}{np}$ converges to $e$ in probability. Uniform temporal trees show some remarkable similarities to uniform random recursive trees.