Joint distribution of the cokernels of random $p$-adic matrices II

TL;DR

This paper investigates the joint distribution of cokernels of certain $p$-adic matrices, characterizing possible module tuples and proving convergence of their distribution for large matrix sizes.

Contribution

It determines the set of possible cokernel tuples for small $m$ and proves the convergence of their joint distribution for Haar random matrices over $Z_p$.

Findings

Characterization of possible cokernel tuples for $m \\le 4$

Convergence of joint distribution of cokernels as matrix size grows

Explicit description of the distribution in the limit

Abstract

In this paper, we study the combinatorial relations between the cokernels $\text{cok}(A_n+px_iI_n)$ ($1 \le i \le m$) where $A_n$ is an $n \times n$ matrix over the ring of $p$-adic integers $\mathbb{Z}_p$, $I_n$ is the $n \times n$ identity matrix and $x_1, \cdots, x_m$ are elements of $ \mathbb{Z}_p$ whose reductions modulo $p$ are distinct. For a positive integer $m \le 4$ and given $x_1, \cdots, x_m \in \mathbb{Z}_p$, we determine the set of $m$-tuples of finitely generated $\mathbb{Z}_p$-modules $(H_1, \cdots, H_m)$ for which $(\text{cok}(A_n+px_1I_n), \cdots, \text{cok}(A_n+px_mI_n)) = (H_1, \cdots, H_m)$ for some matrix $A_n$. We also prove that if $A_n$ is an $n \times n$ Haar random matrix over $\mathbb{Z}_p$ for each positive integer $n$, then the joint distribution of $\text{cok}(A_n+px_iI_n)$ ($1 \le i \le m$) converges as $n \rightarrow \infty$.