English

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

Data Structures and Algorithms 2025-07-08 v1

Abstract

For a directed graph GG, let mindeg(G)\mathrm{mindeg}(G) be the minimum among in-degrees and out-degrees of all vertices of GG. It is easy to see that GG contains a directed cycle of length at least mindeg(G)+1\mathrm{mindeg}(G)+1. In this note, we show that, even if GG is 22-connected, it is NP-hard to check if GG contains a cycle of length at least mindeg(G)+3\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.

Keywords

Cite

@article{arxiv.2507.03807,
  title  = {A note on finding long directed cycles above the minimum degree bound in 2-connected digraphs},
  author = {Jadwiga Czyżewska and Marcin Pilipczuk},
  journal= {arXiv preprint arXiv:2507.03807},
  year   = {2025}
}
R2 v1 2026-07-01T03:47:15.119Z