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Covering Random Digraphs with Hamilton Cycles

Asaf Ferber, Marcelo Sales, Mason Shurman

Abstract

A covering of a digraph $D$ by Hamilton cycles is a collection of directed Hamilton cycles (not necessarily edge-disjoint) that together cover all the edges of $D$. We prove that for $1/2 \geq p\geq \frac{\log^{20} n}{n}$, the random digraph $D_{n,p}$ typically admits an optimal Hamilton cycle covering. Specifically, the edges of $D_{n,p}$ can be covered by a family of $t$ Hamilton cycles, where $t$ is the maximum of the the in-degree and out-degree of the vertices in $D_{n,p}$. Notably, $t$ is the best possible bound, and our assumption on $p$ is optimal up to a polylogarithmic factor.

Covering Random Digraphs with Hamilton Cycles

Abstract

A covering of a digraph by Hamilton cycles is a collection of directed Hamilton cycles (not necessarily edge-disjoint) that together cover all the edges of . We prove that for , the random digraph typically admits an optimal Hamilton cycle covering. Specifically, the edges of can be covered by a family of Hamilton cycles, where is the maximum of the the in-degree and out-degree of the vertices in . Notably, is the best possible bound, and our assumption on is optimal up to a polylogarithmic factor.

Paper Structure

This paper contains 16 sections, 25 theorems, 93 equations.

Key Result

Theorem 1.1

Let $1/2 \geq p\geq\frac{ \log^{20} n}{n}$. Then a digraph $D:=D_{n,p}$ whp can be covered by $\Delta(D)$ directed Hamilton cycles.

Theorems & Definitions (67)

  • Theorem 1.1
  • Theorem 2.1: Chernoff Bound
  • Theorem 2.2: JRLrandomgraphs, Corollary 2.4
  • Theorem 2.3: bergefourniervizing
  • Theorem 2.4: Hall's Theorem
  • Corollary 2.5
  • Lemma 2.6
  • Lemma 2.7: OreStudies63
  • Definition 2.8
  • Lemma 2.9
  • ...and 57 more