English

Packing and covering directed triangles asymptotically

Combinatorics 2021-09-16 v2

Abstract

A well-known conjecture of Tuza asserts that if a graph has at most tt pairwise edge-disjoint triangles, then it can be made triangle-free by removing at most 2t2t edges. If true, the factor 2 would be best possible. In the directed setting, also asked by Tuza, the analogous statement has recently been proven, however, the factor 2 is not optimal. In this paper, we show that if an nn-vertex directed graph has at most tt pairwise arc-disjoint directed triangles, then there exists a set of at most 1.8t+o(n2)1.8t+o(n^2) arcs that meets all directed triangles. We complement our result by presenting two constructions of large directed graphs with tΩ(n2)t\in\Omega(n^2) whose smallest such set has 1.5to(n2)1.5t-o(n^2) arcs.

Keywords

Cite

@article{arxiv.1909.07120,
  title  = {Packing and covering directed triangles asymptotically},
  author = {Jacob W. Cooper and Andrzej Grzesik and Adam Kabela and Daniel Kral},
  journal= {arXiv preprint arXiv:1909.07120},
  year   = {2021}
}
R2 v1 2026-06-23T11:16:30.249Z