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On the Asymptotics of the Connectivity Probability of Random Bipartite Graphs

Boris Chinyaev

TL;DR

This work addresses the exact asymptotics of the connectivity probability $P_{n,m}(p)$ for the bipartite random graph $G(n,m,p)$, allowing $p$ to scale with $(n,m)$. It adapts the inhomogeneous random-walk framework from $G(n,p)$ to the bipartite setting via a nonasymptotic exploration process, establishing a representation that reduces the problem to a conditioned nonnegative trajectory of a two-walk system built from Poisson increments. The main result characterizes $P_{n,m}(p)$ across several regimes $p(n,m)$, including cases where the base edge probability vanishes slowly or rapidly, by providing explicit asymptotic formulas and monotonicity properties with respect to $p$. This framework lays the groundwork for rigorous asymptotics and practical sampling methods for connected bipartite graphs, with potential extensions to broader random-graph models.

Abstract

In this paper, we analyze the exact asymptotic behavior of the connectivity probability in a random binomial bipartite graph $G(n,m,p)$ under various regimes of the edge probability $p=p(n)$. To determine this probability, a method based on the analysis of inhomogeneous random walks is proposed.

On the Asymptotics of the Connectivity Probability of Random Bipartite Graphs

TL;DR

This work addresses the exact asymptotics of the connectivity probability for the bipartite random graph , allowing to scale with . It adapts the inhomogeneous random-walk framework from to the bipartite setting via a nonasymptotic exploration process, establishing a representation that reduces the problem to a conditioned nonnegative trajectory of a two-walk system built from Poisson increments. The main result characterizes across several regimes , including cases where the base edge probability vanishes slowly or rapidly, by providing explicit asymptotic formulas and monotonicity properties with respect to . This framework lays the groundwork for rigorous asymptotics and practical sampling methods for connected bipartite graphs, with potential extensions to broader random-graph models.

Abstract

In this paper, we analyze the exact asymptotic behavior of the connectivity probability in a random binomial bipartite graph under various regimes of the edge probability . To determine this probability, a method based on the analysis of inhomogeneous random walks is proposed.

Paper Structure

This paper contains 6 sections, 4 theorems, 28 equations, 2 figures.

Key Result

Lemma 2.1

Let $G(n,p)$ be an Erdős–Rényi graph. Then the connectivity probability is given by where $S_k = \sum_{i=1}^{k} X_i$, and $X_i$ are independent random variables such that $X_i + 1\sim Poiss\left(\lambda_i\right)$, with

Figures (2)

  • Figure 1: Plot of the expected value and sample realizations of $S_k$.
  • Figure 2: Plot of sample realizations of $B_k$ and $V_{k}^{A}.$

Theorems & Definitions (6)

  • Lemma 2.1: chinyaev2024er_eng
  • Lemma 2.2: Connectivity Probability of $G(n,m,p)$
  • proof
  • Lemma 2.3: Monotonicity
  • proof
  • Theorem 2.1: On the Connectivity Probability of $G(n,m,p)$