Saved in:
| Main Authors: | , |
|---|---|
| Format: | Preprint |
| Published: |
2024
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2411.06982 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866918321286283264 |
|---|---|
| author | Patel, Viresh Yıldız, Mehmet Akif |
| author_facet | Patel, Viresh Yıldız, Mehmet Akif |
| contents | We consider the problem of decomposing the edges of a digraph into as few paths as possible. A natural lower bound for the number of paths in any path decomposition of a digraph $D$ is $\frac{1}{2}\sum_{v\in V(D)}|d^+(v)-d^-(v)|$; any digraph that achieves this bound is called consistent. Alspach, Mason, and Pullman conjectured in 1976 that every tournament of even order is consistent and this was recently verified for large tournaments by Girão, Granet, Kühn, Lo, and Osthus. A more general conjecture of Pullman states that for odd $d$, every orientation of a $d$-regular graph is consistent. We prove that the conjecture holds for random $d$-regular graphs with high probability i.e. for fixed odd $d$ and as $n \to \infty$ the conjecture holds for almost all $d$-regular graphs. Along the way, we verify Pullman's conjecture for graphs whose girth is sufficiently large (as a function of the degree). |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_06982 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Path decompositions of oriented graphs Patel, Viresh Yıldız, Mehmet Akif Combinatorics We consider the problem of decomposing the edges of a digraph into as few paths as possible. A natural lower bound for the number of paths in any path decomposition of a digraph $D$ is $\frac{1}{2}\sum_{v\in V(D)}|d^+(v)-d^-(v)|$; any digraph that achieves this bound is called consistent. Alspach, Mason, and Pullman conjectured in 1976 that every tournament of even order is consistent and this was recently verified for large tournaments by Girão, Granet, Kühn, Lo, and Osthus. A more general conjecture of Pullman states that for odd $d$, every orientation of a $d$-regular graph is consistent. We prove that the conjecture holds for random $d$-regular graphs with high probability i.e. for fixed odd $d$ and as $n \to \infty$ the conjecture holds for almost all $d$-regular graphs. Along the way, we verify Pullman's conjecture for graphs whose girth is sufficiently large (as a function of the degree). |
| title | Path decompositions of oriented graphs |
| topic | Combinatorics |
| url | https://arxiv.org/abs/2411.06982 |