English

Path decompositions of Eulerian graphs

Combinatorics 2025-10-16 v1

Abstract

Gallai's conjecture asserts that every connected graph on nn vertices can be decomposed into n+12\frac{n+1}{2} paths. For general graphs (possibly disconnected), it was proved that every graph on nn vertices can be decomposed into 2n3\frac{2n}{3} paths. This is also best possible (consider the graphs consisting of vertex-disjoint triangles). Lov\'{a}sz showed that every nn-vertex graph with at most one vertex of even degree can be decomposed into n2\frac{n}{2} paths. However, Gallai's conjecture is difficult for graphs with many vertices of even degrees. Favaron and Kouider verified Gallai's conjecture for all Eulerian graphs with maximum degree at most 44. In this paper, we show if GG is an Eulerian graph on n4n \ge 4 vertices and the distance between any two triangles in GG is at least 33, then GG can be decomposed into at most 3n5\frac{3n}{5} paths.

Keywords

Cite

@article{arxiv.2510.12806,
  title  = {Path decompositions of Eulerian graphs},
  author = {Yanan Chu and Yan Wang},
  journal= {arXiv preprint arXiv:2510.12806},
  year   = {2025}
}
R2 v1 2026-07-01T06:37:16.177Z