A note on digraph splitting

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Název: A note on digraph splitting
Autoři: Micha Christoph, Kalina Petrova, Raphael Steiner
Zdroj: Combinatorics, Probability and Computing. 34:559-564
Publication Status: Preprint
Informace o vydavateli: Cambridge University Press (CUP), 2025.
Rok vydání: 2025
Témata: Combinatorics, splitting, FOS: Mathematics, Digraph, minimum out-degree, Combinatorics (math.CO), directed graphs
Popis: A tantalizing open problem, posed independently by Stiebitz in 1995 and by Alon in 1996 and again in 2006, asks whether for every pair of integers $s,t \ge 1$ there exists a finite number $F(s,t)$ such that the vertex set of every digraph of minimum out-degree at least $F(s,t)$ can be partitioned into non-empty parts $A$ and $B$ such that the subdigraphs induced on $A$ and $B$ have minimum out-degree at least $s$ and $t$ , respectively.In this short note, we prove that if $F(2,2)$ exists, then all the numbers $F(s,t)$ with $s,t\ge 1$ exist and satisfy $F(s,t)=\Theta (s+t)$ . In consequence, the problem of Alon and Stiebitz reduces to the case $s=t=2$ . Moreover, the numbers $F(s,t)$ with $s,t \ge 2$ either all exist and grow linearly, or all of them do not exist.
Druh dokumentu: Article
Jazyk: English
ISSN: 1469-2163
0963-5483
DOI: 10.1017/s0963548325000045
DOI: 10.3929/ethz-b-000728804
DOI: 10.48550/arxiv.2310.08449
Přístupová URL adresa: http://arxiv.org/abs/2310.08449
Rights: CC BY
arXiv Non-Exclusive Distribution
Přístupové číslo: edsair.doi.dedup.....f4d4b2b3689cfa580c6eb41a56549431
Databáze: OpenAIRE
Popis
Abstrakt:A tantalizing open problem, posed independently by Stiebitz in 1995 and by Alon in 1996 and again in 2006, asks whether for every pair of integers $s,t \ge 1$ there exists a finite number $F(s,t)$ such that the vertex set of every digraph of minimum out-degree at least $F(s,t)$ can be partitioned into non-empty parts $A$ and $B$ such that the subdigraphs induced on $A$ and $B$ have minimum out-degree at least $s$ and $t$ , respectively.In this short note, we prove that if $F(2,2)$ exists, then all the numbers $F(s,t)$ with $s,t\ge 1$ exist and satisfy $F(s,t)=\Theta (s+t)$ . In consequence, the problem of Alon and Stiebitz reduces to the case $s=t=2$ . Moreover, the numbers $F(s,t)$ with $s,t \ge 2$ either all exist and grow linearly, or all of them do not exist.
ISSN:14692163
09635483
DOI:10.1017/s0963548325000045