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Consider any dense r-regular quasirandom bipartite graph H with parts of size n and fix a set of r colours. Let L be a random list assignment where each colour is available for each edge of H with probability p. We show that the threshold…

Combinatorics · Mathematics 2022-12-09 Peter Keevash

We prove that the vertex degree threshold for tiling $\C_4^3$ (the 3-uniform hypergraph with four vertices and two triples) in a 3-uniform hypergraph on $n\in 4\mathbb N$ vertices is $\binom{n-1}2 - \binom{\frac34 n}2+\frac38n+c$, where…

Combinatorics · Mathematics 2014-08-14 Jie Han , Yi Zhao

A graph $G$ admits an $H$-tiling if it contains a collection of vertex-disjoint copies of $H$. In this paper, we confirm a conjecture proposed by K\"{u}hn, Osthus, and Treglown by showing that for any given graph $H$, there exists a…

Combinatorics · Mathematics 2026-05-25 Yuping Gao , Yilin Guo , Guanghui Wang , Lin-Peng Zhang

Let $\chi'_\subset(G)$ be the least number of colours necessary to properly colour the edges of a graph $G$ with minimum degree $\delta\geq 2$ so that the set of colours incident with any vertex is not contained in a set of colours incident…

Combinatorics · Mathematics 2019-09-04 Jakub Kwaśny , Jakub Przybyło

Komlos [Tiling Turan theorems, Combinatorica, 20,2 (2000), 203{218] determined the asymptotically optimal minimum degree condition for covering a given proportion of vertices of a host graph by vertex-disjoint copies of a fixed graph. We…

Combinatorics · Mathematics 2018-12-21 Diana Piguet , Maria Saumell

We establish a best-possible minimum codegree condition for the existence of a perfect tiling of a $3$-uniform hypergraph $H$ with copies of the generalised triangle $T$, which is the 3-uniform hypergraph with five vertices $a, b, c, d, e$…

Combinatorics · Mathematics 2025-05-12 Candida Bowtell , Amarja Kathapurkar , Natasha Morrison , Richard Mycroft

We study the problem of finding a minimum $k$-critical-bipartite graph of order $(n,m)$: a bipartite graph $G=(U,V;E)$, with $|U|=n$, $|V|=m$, and $n>m>1$, which is $k$-critical-bipartite, and the tuple $(|E|, \Delta_U, \Delta_V)$, where…

Combinatorics · Mathematics 2023-07-17 Sylwia Cichacz , Agieszka Görlich , Karol Suchan

The chromatic threshold $\delta_\chi(H)$ of a graph $H$ is the infimum of $d>0$ such that the chromatic number of every $n$-vertex $H$-free graph with minimum degree at least $d n$ is bounded by a constant depending only on $H$ and $d$.…

Combinatorics · Mathematics 2026-02-24 Jaehoon Kim , Hong Liu , Chong Shangguan , Guanghui Wang , Zhuo Wu , Yisai Xue

A star edge coloring of a graph is a proper edge coloring with no $2$-colored path or cycle of length four. The star chromatic index $\chi'_{st}(G)$ of $G$ is the minimum number $t$ for which $G$ has a star edge coloring with $t$ colors. We…

Combinatorics · Mathematics 2021-05-12 Carl Johan Casselgren , Jonas B. Granholm , André Raspaud

The problem of chromatic thresholds seeks for minimum degree conditions that ensure $H$-free graphs to have a bounded chromatic number, or equivalently a bounded size homomorphic image. The strengthened homomorphism thresholds problem…

Combinatorics · Mathematics 2025-02-14 Xinqi Huang , Hong Liu , Mingyuan Rong , Zixiang Xu

A graph $G$ is $H$-free, if it contains no $H$ as a subgraph. A graph is said to be \emph{$H$-minor free}, if it does not contain $H$ as a minor. In recent years, Nikiforov asked that what is the maximum spectral radius of an $H$-free graph…

Combinatorics · Mathematics 2023-02-08 Yuan Ren , Jing Zhang , Zhiyuan Zhang

We prove that there exists an absolute constant $C>0$ such that, for any positive integer $k$, every graph $G$ with minimum degree at least $Ck$ admits a vertex-partition $V(G)=S\cup T$, where both $G[S]$ and $G[T]$ have minimum degree at…

Combinatorics · Mathematics 2023-06-16 Jie Ma , Hehui Wu

We consider the problem of constructing a bipartite graph whose degrees lie in prescribed intervals. Necessary and sufficient conditions for the existence of such graphs are well-known. However, existing realization algorithms suffer from…

Data Structures and Algorithms · Computer Science 2017-08-21 Steffen Rechner

Erd\H{o}s and Simonovits asked the following question: For an integer $r\geq 2$ and a family of non-bipartite graphs $\mathcal{H}$, determine the infimum of $\alpha$ such that any $\mathcal{H}$-free $n$-vertex graph with minimum degree at…

Combinatorics · Mathematics 2025-04-10 Xiaoli Yuan , Yuejian Peng

Consider a random bipartite multigraph $G$ with $n$ left nodes and $m \geq n \geq 2$ right nodes. Each left node $x$ has $d_x \geq 1$ random right neighbors. The average left degree $\Delta$ is fixed, $\Delta \geq 2$. We ask whether for the…

Discrete Mathematics · Computer Science 2012-04-30 Martin Dietzfelbinger , Michael Rink

A bisection of a graph is a bipartition of its vertex set such that the two resulting parts differ in size by at most 1, and its size is the number of edges that connect vertices in the two parts. The perfect matching condition and…

Combinatorics · Mathematics 2024-11-19 Jianfeng Hou , Shufei Wu , Yuanyuan Zhong

Let $G$ be a connected graph. If $G$ contains a matching of size $k$, and every matching of size $k$ is contained in a perfect matching of $G$, then $G$ is said to be \emph{$k$-extendable}. A $k$-regular spanning subgraph of $G$ is called a…

Combinatorics · Mathematics 2022-11-18 Dandan Fan , Huiqiu Lin

For a bipartite graph $H$, its linear threshold is the smallest real number $\sigma$ such that every bipartite graph $G = (U \sqcup V, E)$ with unbalanced parts $|V| \gtrsim |U|^\sigma$ and without a copy of $H$ must have a linear number of…

Combinatorics · Mathematics 2025-06-16 Lili Ködmön , Anqi Li , Ji Zeng

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

Let ${\cal{F}}=\{F_1,F_2,\ldots\}$ be a sequence of graphs such that $F_n$ is a graph on $n$ vertices with maximum degree at most $\Delta$. We show that there exists an absolute constant $C$ such that the vertices of any 2-edge-colored…

Combinatorics · Mathematics 2014-05-30 Andrey Grinshpun , Gabor N. Sarkozy