文摘
We prove that the (non-symmetric) adjacency matrix of a uniform random d-regular directed graph on n vertices is asymptotically almost surely invertible, assuming \(\min (d,n-d)\ge C\log ^2n\) for a sufficiently large constant \(C>0\). The proof makes use of a coupling of random regular digraphs formed by “shuffling” the neighborhood of a pair of vertices, as well as concentration results for the distribution of edges, proved in Cook (Random Struct Algorithms. arXiv:1410.5595, 2014). We also apply our general approach to prove asymptotically almost surely invertibility of Hadamard products \(\varSigma {{\mathrm{\circ }}}\varXi \), where \(\varXi \) is a matrix of iid uniform \(\pm 1\) signs, and \(\varSigma \) is a 0/1 matrix whose associated digraph satisfies certain “expansion” properties.