Random integral matrices: universality of surjectivity and the cokernel

Abstract

For a random matrix of entries sampled independently from a fairly general distribution in \({{\mathbf {Z}}}\) we study the probability that the cokernel is isomorphic to a given finite abelian group, or when it is cyclic. This includes the probability that the linear map between the integer lattices given by the matrix is surjective. We show that these statistics are asymptotically universal (as the size of the matrix goes to infinity), given by precise formulas involving zeta values, and agree with distributions defined by Cohen and Lenstra, even when the distribution of matrix entries is very distorted. Our method is robust and works for Laplacians of random digraphs and sparse matrices with the probability of an entry non-zero only \(n^{-1+\varepsilon }\).