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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

The following sharpening of Tur\'an's theorem is proved. Let $T_{n,p}$ denote the complete $p$--partite graph of order $n$ having the maximum number of edges. If $G$ is an $n$-vertex $K_{p+1}$-free graph with $e(T_{n,p})-t$ edges then there…

Combinatorics · Mathematics 2015-01-14 Zoltán Füredi

A well known theorem in graph theory states that every graph $G$ on $n$ vertices and minimum degree at least $d$ contains a path of length at least $d$, and if $G$ is connected and $n\ge 2d+1$ then $G$ contains a path of length at least…

Combinatorics · Mathematics 2019-03-12 Yue Ma , Xinmin Hou , Jun Gao

We study theorems giving sufficient conditions on the vertex degrees of a graph $G$ to guarantee $G$ is $t$-tough. We first give a best monotone theorem when $t\ge1$, but then show that for any integer $k\ge1$, a best monotone theorem for…

Combinatorics · Mathematics 2011-05-27 D. Bauer , H. J. Broersma , J. van den Heuvel , N. Kahl , E. Schmeichel

In this paper we consider a variation of the classical Tur\'{a}n-type extremal problems. Let $S$ be an $n$-term graphical sequence, and $\sigma(S)$ be the sum of the terms in $S$. Let $H$ be a graph. The problem is to determine the smallest…

Combinatorics · Mathematics 2007-05-23 Chunhui Lai

Given a collection $\mathcal{G}=(G_1,\dots, G_h)$ of graphs on the same vertex set $V$ of size $n$, an $h$-edge graph $H$ on the vertex set $V$ is a $\mathcal{G}$-transversal if there exists a bijection $\lambda : E(H) \rightarrow [h]$ such…

Combinatorics · Mathematics 2023-02-21 Debsoumya Chakraborti , Seonghyuk Im , Jaehoon Kim , Hong Liu

Our main result is that every graph $G$ on $n\ge 10^4r^3$ vertices with minimum degree $\delta(G) \ge (1 - 1 / 10^4 r^{3/2} ) n$ has a fractional $K_r$-decomposition. Combining this result with recent work of Barber, K\"uhn, Lo and Osthus…

Combinatorics · Mathematics 2018-09-05 Ben Barber , Daniela Kühn , Allan Lo , Richard Montgomery , Deryk Osthus

A fundamental result of Mader from 1972 asserts that a graph of high average degree contains a highly connected subgraph with roughly the same average degree. We prove a lemma showing that one can strengthen Mader's result by replacing the…

Combinatorics · Mathematics 2013-05-21 Asaf Shapira , Benny Sudakov

We prove that any graph $G$ of minimum degree greater than $2k^2-1$ has a $(k+1)$-connected induced subgraph $H$ such that the number of vertices of $H$ that have neighbors outside of $H$ is at most $2k^2-1$. This generalizes a classical…

Combinatorics · Mathematics 2016-11-04 Irena Penev , Stéphan Thomassé , Nicolas Trotignon

A graph $G$ is $k$-path-coverable if its vertex set $V(G)$ can be covered by $k$ or fewer vertex disjoint paths. In this paper, using the $Q$-index of a connected graph $G$, we present a tight sufficient condition for $G$ with fixed minimum…

Combinatorics · Mathematics 2021-09-16 Tao Cheng , Lihua Feng , Yongtao Li , Weijun Liu

B. Bollob\'{a}s and G. Brightwell and independently R. Shi proved the existence of a cycle through all vertices whose degrees at least $\frac{n}{2}$ in any $2$-connected graph of order $n$. Motivated by this result, we prove the existence…

Combinatorics · Mathematics 2025-02-12 Chengli Li , Leyou Xu

The distinguishing index of a simple graph $G$, denoted by $D'(G)$, is the least number of labels in an edge labeling of $G$ not preserved by any non-trivial automorphism. It was conjectured by Pil\'sniak (2015) that for any 2-connected…

Combinatorics · Mathematics 2017-02-14 Saeid Alikhani , Samaneh Soltani

An oriented graph $H$ is Tur\'anable (resp. tileable) if there exist $n_0 \in \mathbb{N}$ such that every semi-regular near-tournament on $n \ge n_0$ vertices contains a copy of $H$ (resp. a perfect $H$-tiling). We disprove a conjectured…

Combinatorics · Mathematics 2026-03-20 Igor Araujo , Zimu Xiang

The degree distribution of a graph $G=(V,E)$, $|V|=n$, $|E|=m$ is one of the most fundamental objects of study in the analysis of graphs as it embodies relationship among entities. In particular, an important derived distribution from…

Data Structures and Algorithms · Computer Science 2025-07-30 Arijit Bishnu , Debarshi Chanda , Gopinath Mishra

Given a set D of nonnegative integers, we derive the asymptotic number of graphs with a givenvnumber of vertices, edges, and such that the degree of every vertex is in D. This generalizes existing results, such as the enumeration of graphs…

Combinatorics · Mathematics 2015-07-22 Élie de Panafieu , Lander Ramos

The fundamental theorem of Tur\'{a}n from Extremal Graph Theory determines the exact bound on the number of edges $t_r(n)$ in an $n$-vertex graph that does not contain a clique of size $r+1$. We establish an interesting link between…

Data Structures and Algorithms · Computer Science 2023-07-17 Fedor V. Fomin , Petr A. Golovach , Danil Sagunov , Kirill Simonov

Given $a,b,c\in\mathbb N$, let $D_{a,b,c}$ be the tournament on $a+b+c$ vertices obtained by replacing the vertices of the directed triangle $C_3$ with transitive tournaments $TT_a$, $TT_b$, and $TT_c$, respectively. Keevash and Sudakov…

Combinatorics · Mathematics 2026-03-24 Ming Chen , Wenxu Lu , Yun Wang , Zhiwei Zhang

Let $G$ be a simple graph with maximum degree $\Delta(G)$. A subgraph $H$ of $G$ is overfull if $|E(H)|>\Delta(G)\lfloor \frac{1}{2}|V(H)| \rfloor$. Chetwynd and Hilton in 1986 conjectured that a graph $G$ with $\Delta(G)>\frac{1}{3}|V(G)|$…

Combinatorics · Mathematics 2022-06-28 Songling Shan

The crossing number of a graph is the minimum number of crossings in a drawing of the graph in the plane. Our main result is that every graph $G$ that does not contain a fixed graph as a minor has crossing number $O(\Delta n)$, where $G$…

Combinatorics · Mathematics 2018-08-01 Vida Dujmović , Ken-ichi Kawarabayashi , Bojan Mohar , David R. Wood

Loebl, Koml\'os, and S\'os conjectured that any graph with at least half of its vertices of degree at least k contains every tree with at most k edges. We propose a version of this conjecture for skewed trees, i.e., we consider the class of…

Combinatorics · Mathematics 2018-02-05 Tereza Klimošová , Diana Piguet , Václav Rozhoň