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We consider special cases of the two tree degree sequences problem. We show that if two tree degree sequences do not have common leaves then they always have edge-disjoint caterpillar realizations. By using a probabilistic method, we prove…

Combinatorics · Mathematics 2017-04-25 Kristóf Bérczi , Zoltán Király , Changshuo Liu , István Miklós

We prove that if $T_1,\dots, T_n$ is a sequence of bounded degree trees so that $T_i$ has $i$ vertices, then $K_n$ has a decomposition into $T_1,\dots, T_n$. This shows that the tree packing conjecture of Gy\'arf\'as and Lehel from 1976…

Combinatorics · Mathematics 2019-03-14 Felix Joos , Jaehoon Kim , Daniela Kühn , Deryk Osthus

Perhaps the very first elementary exercise one encounters in graph theory is the result that any graph on at least two vertices must have at least two vertices with the same degree. There are various ways in which this result can be…

Combinatorics · Mathematics 2018-06-22 Yair Caro , Josef Lauri , Christina Zarb

Let $K$ be a complete graph of order $n$. For $d\in (0,1)$, let $c$ be a $\pm 1$-edge labeling of $K$ such that there are $d{n\choose 2}$ edges with label $+1$, and let $G$ be a spanning subgraph of $K$ of maximum degree at most $\Delta$.…

Combinatorics · Mathematics 2021-11-12 Stéphane Bessy , Johannes Pardey , Lucas Picasarri-Arrieta , Dieter Rautenbach

Bondy and Vince showed that every graph with minimum degree at least three contains two cycles of lengths differing by one or two.We prove the following average degree counterpart that every $n$-vertex graph $G$ with at least $\frac52(n-1)$…

Combinatorics · Mathematics 2022-10-11 Jun Gao , Binlong Li , Jie Ma , Tianying Xie

A subgraph $H$ of a multigraph $G$ is overfull if $ |E(H) | > \Delta(G) \lfloor |V(H)|/2 \rfloor$. Analogous to the Overfull Conjecture proposed by Chetwynd and Hilton in 1986, Stiebitz et al. in 2012 formed the multigraph version of the…

Combinatorics · Mathematics 2023-07-13 Michael J. Plantholt , Songling Shan

Given a simple graph $G$, denote by $\Delta(G)$, $\delta(G)$, and $\chi'(G)$ the maximum degree, the minimum degree, and the chromatic index of $G$, respectively. We say $G$ is \emph{$\Delta$-critical} if $\chi'(G)=\Delta(G)+1$ and…

Combinatorics · Mathematics 2021-05-13 Yan Cao , Guantao Chen , Guangming Jing , Songling Shan

A set $S$ of vertices in a graph is an open packing if (open) neighborhoods of any two distinct vertices in $S$ are disjoint. In this paper, we consider the graphs that have a unique maximum open packing. We characterize the trees with this…

Combinatorics · Mathematics 2019-01-29 Boštjan Brešar , Kirsti Kuenzel , Douglas F. Rall

The linear arboricity of a graph $G$, denoted by $\text{la}(G)$, is the minimum number of edge-disjoint linear forests (i.e. forests in which every connected component is a path) in $G$ whose union covers all the edges of $G$. A famous…

Combinatorics · Mathematics 2018-09-14 Asaf Ferber , Jacob Fox , Vishesh Jain

We investigate the list packing number of a graph, the least $k$ such that there are always $k$ disjoint proper list-colourings whenever we have lists all of size $k$ associated to the vertices. We are curious how the behaviour of the list…

Combinatorics · Mathematics 2024-11-20 Stijn Cambie , Wouter Cames van Batenburg , Ewan Davies , Ross J. Kang

A set $S\subseteq V$ of vertices of a graph $G$ is a $c$-clustered set if it induces a subgraph with components of order at most $c$ each, and $\alpha_c(G)$ denotes the size of a largest $c$-clustered set. For any graph $G$ on $n$ vertices…

Combinatorics · Mathematics 2026-05-21 Kolja Knauer , Torsten Ueckerdt

In \cite{reed97}, Reed conjectures that the inequality $\chi (G) \leq \left \lceil \textstyle {1/2} (\omega (G) + \Delta (G) + 1) \right \rceil$ holds for any graph $G$. We prove this holds for a graph $G$ if $\bar{G}$ is disconnected. From…

Combinatorics · Mathematics 2007-05-23 landon rabern

We prove that one can perfectly pack degenerate graphs into complete or dense $n$-vertex quasirandom graphs, provided that all the degenerate graphs have maximum degree $o(\frac{n}{\log n})$, and in addition $\Omega(n)$ of them have at most…

Combinatorics · Mathematics 2019-06-28 Peter Allen , Julia Böttcher , Dennis Clemens , Anusch Taraz

In 1975 Bollob\'{a}s, Erd\H{o}s, and Szemer\'{e}di asked what minimum degree guarantees an octahedral subgraph $K_3(2)$ in any tripartite graph $G$ with $n$ vertices in each vertex class. We show that $\delta(G)\geq n+2n^{\frac{5}{6}}$…

Combinatorics · Mathematics 2025-06-24 Yihan Chen , Jialin He , Allan Lo , Cong Luo , Jie Ma , Yi Zhao

A collection of graphs is \textit{nearly disjoint} if every pair of them intersects in at most one vertex. We prove that if $G_1, \dots, G_m$ are nearly disjoint graphs of maximum degree at most $D$, then the following holds. For every…

Combinatorics · Mathematics 2023-10-31 Tom Kelly , Daniela Kühn , Deryk Osthus

A $k$-block in a graph $G$ is a maximal set of at least $k$ vertices no two of which can be separated in $G$ by deleting fewer than $k$ vertices. The block number $\beta(G)$ of $G$ is the maximum integer $k$ for which $G$ contains a…

Combinatorics · Mathematics 2017-02-15 Daniel Weißauer

The Ascending Subgraph Decomposition (ASD) Conjecture asserts that every graph $G$ with ${n+1\choose 2}$ edges admits an edge decomposition $G=H_1\oplus\cdots \oplus H_n$ such that $H_i$ has $i$ edges and it is isomorphic to a subgraph of…

Combinatorics · Mathematics 2015-12-08 Anna Lladó , Josep Maria Aroca

We say that a graph $G$ has a perfect $H$-packing if there exists a set of vertex-disjoint copies of $H$ which cover all the vertices in $G$. The seminal Hajnal--Szemer\'edi theorem characterises the minimum degree that ensures a graph $G$…

Combinatorics · Mathematics 2016-01-25 Andrew Treglown

We provide a degree condition on a regular $n$-vertex graph $G$ which ensures the existence of a near optimal packing of any family $\mathcal H$ of bounded degree $n$-vertex $k$-chromatic separable graphs into $G$. In general, this degree…

Combinatorics · Mathematics 2018-11-12 Padraig Condon , Jaehoon Kim , Daniela Kühn , Deryk Osthus

Given a graph $G$, a geodesic packing in $G$ is a set of vertex-disjoint maximal geodesics, and the geodesic packing number of $G$, ${\gpack}(G)$, is the maximum cardinality of a geodesic packing in $G$. It is proved that the decision…

Combinatorics · Mathematics 2023-07-06 Paul Manuel , Bostjan Bresar , Sandi Klavzar