English

Counting strongly connected $(k_1,k_2)$-directed cores

Combinatorics 2016-09-02 v1 Probability

Abstract

Consider the set of all digraphs on [N][N] with MM edges, whose minimum in-degree and minimum out-degree are at least k1k_1 and k2k_2 respectively. For k:=min{k1,k2}2k:=\min\{k_1,k_2\}\ge 2 and M/N>max{k1,k2}M/N>\max\{k_1,k_2\}, M=Θ(N)M=\Theta(N), we show that, among those digraphs, the fraction of kk-strongly connected digraphs is 1O(N(k1))1-O\bigl(N^{-(k-1)}). Earlier with Dan Poole we identified a sharp edge-density threshold c(k1,k2)c^*(k_1,k_2) for birth of a giant (k1,k2)(k_1,k_2)-core in the random digraph D(n,m=[cn])D(n,m=[cn]). Combining the claims, for c>c(k1,k2)c>c^*(k_1,k_2) with probability 1O(N(k1))1-O\bigl(N^{-(k-1)}) the giant (k1,k2)(k_1,k_2)-core exists and is kk-strongly connected.

Keywords

Cite

@article{arxiv.1609.00290,
  title  = {Counting strongly connected $(k_1,k_2)$-directed cores},
  author = {Boris Pittel},
  journal= {arXiv preprint arXiv:1609.00290},
  year   = {2016}
}
R2 v1 2026-06-22T15:37:48.469Z