A note on finding long directed cycles above the minimum degree bound in 2-connected digraphs

For a directed graph $G$, let $\mathrm{mindeg}(G)$ be the minimum among in-degrees and out-degrees of all vertices of $G$. It is easy to see that $G$ contains a directed cycle of length at least $\mathrm{mindeg}(G)+1$. In this note, we show that, even if $G$ is $2$-connected, it is NP-hard to check if $G$ contains a cycle of length at least $\mathrm{mindeg}(G)+3$. This is in contrast with recent algorithmic results of Fomin, Golovach, Sagunov, and Simonov [SODA 2022] for analogous questions in undirected graphs.

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Publication Details

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ArXiv.org
Published
2025-07-04
Primary Topic
Interconnection Networks and Systems
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article
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article

A note on finding long directed cycles above the minimum degree bound in 2-connected digraphs

Jadwiga Czyżewska, Marcin Pilipczuk
ArXiv.org
Interconnection Networks and Systems
article

A note on finding long directed cycles above the minimum degree bound in 2-connected digraphs

Jadwiga Czyżewska, Marcin Pilipczuk
article en

Abstract

For a directed graph $G$, let $\mathrm{mindeg}(G)$ be the minimum among in-degrees and out-degrees of all vertices of $G$. It is easy to see that $G$ contains a directed cycle of length at least $\mathrm{mindeg}(G)+1$. In this note, we show that, even if $G$ is $2$-connected, it is NP-hard to check if $G$ contains a cycle of length at least $\mathrm{mindeg}(G)+3$. This is in contrast with recent algorithmic results of Fomin, Golovach, Sagunov, and Simonov [SODA 2022] for analogous questions in undirected graphs.

ArXiv.org
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Interconnection Networks and Systems
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A note on finding long directed cycles above the minimum degree bound in 2-connected digraphs — Jadwiga Czyżewska, Marcin Pilipczuk · ArXiv.org (2025) | TGRS Research Map | TGRS