Published online by Cambridge University Press: 24 June 2020
Let $\{D_M\}_{M\geq 0}$ be the n-vertex random directed graph process, where
$D_0$ is the empty directed graph on n vertices, and subsequent directed graphs in the sequence are obtained by the addition of a new directed edge uniformly at random. For each
$$\varepsilon> 0$$, we show that, almost surely, any directed graph
$D_M$ with minimum in- and out-degree at least 1 is not only Hamiltonian (as shown by Frieze), but remains Hamiltonian when edges are removed, as long as at most
$1/2-\varepsilon$ of both the in- and out-edges incident to each vertex are removed. We say such a directed graph is
$(1/2-\varepsilon)$-resiliently Hamiltonian. Furthermore, for each
$\varepsilon > 0$, we show that, almost surely, each directed graph
$D_M$ in the sequence is not
$(1/2+\varepsilon)$-resiliently Hamiltonian.
This improves a result of Ferber, Nenadov, Noever, Peter and Škorić who showed, for each $\varepsilon > 0$, that the binomial random directed graph
$D(n,p)$ is almost surely
$(1/2-\varepsilon)$-resiliently Hamiltonian if
$p=\omega(\log^8n/n)$.