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The Tur\'{a}n number of a graph $H$, denoted $\mbox{ex}(n,H)$, is the maximum number of edges in an $n$-vertex graph with no subgraph isomorphic to $H$. Solymosi conjectured that if $H$ is any graph and $\mbox{ex}(n,H) = O(n^{\alpha})$…

Combinatorics · Mathematics 2013-12-12 Craig Timmons , Jacques Verstraete

The classical K\H{o}v\'ari-S\'os-Tur\'an theorem states that if $G$ is an $n$-vertex graph with no copy of $K_{s,t}$ as a subgraph, then the number of edges in $G$ is at most $O(n^{2-1/s})$. We prove that if one forbids $K_{s,t}$ as an…

Combinatorics · Mathematics 2017-10-19 Po-Shen Loh , Michael Tait , Craig Timmons , Rodrigo Zhou

The Tur\'an number of a graph H, ex(n,H), is the maximum number of edges in a graph on n vertices which does not have H as a subgraph. Let P_k be the path with k vertices, the square P^2_k of P_k is obtained by joining the pairs of vertices…

Combinatorics · Mathematics 2019-12-06 Chuanqi Xiao , Gyula O. H. Katona , Jimeng Xiao , Oscar Zamora

For integers $k, \ell \geq 3$, let $\mathrm{ex}(n, \overrightarrow{C_k}, \overrightarrow{C_\ell})$ denote the maximum number of directed cycles of length $k$ in any oriented graph on $n$ vertices which does not contain a directed cycle of…

Combinatorics · Mathematics 2025-05-29 Andrzej Grzesik , Justyna Jaworska , Bartłomiej Kielak , Piotr Kuc , Tomasz Ślusarczyk

For a fixed set of positive integers $R$, we say $\mathcal{H}$ is an $R$-uniform hypergraph, or $R$-graph, if the cardinality of each edge belongs to $R$. For a graph $G=(V,E)$, a hypergraph $\mathcal{H}$ is called a Berge-$G$, denoted by…

Combinatorics · Mathematics 2019-05-24 Linyuan Lu , Zhiyu Wang

The Tur\'{a}n number of a graph $H$ is the maximum number of edges in any graph of order $n$ that does not contain $H$ as a subgraph. In 1959, Erd\H os and Gallai obtained a sharp upper bound of Tur\'{a}n numbers for a path of arbitrary…

Combinatorics · Mathematics 2025-11-04 Miao Dong , Bo Ning , Long-Tu Yuan , Xiao-Dong Zhang

For a graph $G$ whose degree sequence is $d_{1},..., d_{n}$, and for a positive integer $p$, let $e_{p}(G)=\sum_{i=1}^{n}d_{i}^{p}$. For a fixed graph $H$, let $t_{p}(n,H)$ denote the maximum value of $e_{p}(G)$ taken over all graphs with…

Combinatorics · Mathematics 2007-05-23 Y. Caro , R. Yuster

Hajos' conjecture that every simple even graph on $n$ vertices can be decomposed into at most $(n-1)/2$ cycles (see L. Lovasz, On covering of graphs, in: P. Erdos, G.O.H. Katona (Eds.), Theory of Graphs, Academic Press, New York, 1968, pp.…

Combinatorics · Mathematics 2015-01-09 Chunhui Lai , Mingjing Liu

As a variant of the much studied Tur\'an number, $ex(n,F)$, the largest number of edges that an $n$-vertex $F$-free graph may contain, we introduce the connected Tur\'an number $ex_c(n,F)$, the largest number of edges that an $n$-vertex…

Combinatorics · Mathematics 2022-08-15 Yair Caro , Balázs Patkós , Zsolt Tuza

Let $\mathcal{F}$ be a set of graphs. The planar Tur\'an number, $ex_{\mathcal{P}}(n,\mathcal{F})$, is the maximum number of edges in an $n$-vertex planar graph which does not contain any member of $\mathcal{F}$ as a subgraph. In this…

Combinatorics · Mathematics 2024-04-09 Tao Fang

An edge-colored graph $F$ is {\it rainbow} if each edge of $F$ has a unique color. The {\it rainbow Tur\'an number} $\mathrm{ex}^*(n,F)$ of a graph $F$ is the maximum possible number of edges in a properly edge-colored $n$-vertex graph with…

Combinatorics · Mathematics 2020-09-02 Anastasia Halfpap , Cory Palmer

The Ruzsa-Szemer\'{e}di $(6,3)$-problem can be equivalently stated as determining the maximum number of edge-disjoint triangles on $n$ vertices such that no triangle is formed by edges from three distinct triangle-copies. Gowers and Janzer…

Combinatorics · Mathematics 2026-03-25 Ping Li

Given integers $r > t \ge 1$ and a real number $p > 0$, the $(t,p)$-norm $\left\lVert \mathcal{H} \right\rVert_{t,p}$ of an $r$-graph $\mathcal{H}$ is the sum of the $p$-th power of the degrees $d_{\mathcal{H}}(T)$ over all $t$-subsets $T…

Combinatorics · Mathematics 2024-06-25 Wanfang Chen , Daniel Iľkovič , Jared León , Xizhi Liu , Oleg Pikhurko

For given graphs $G$ and $F$, the Tur\'an number $ex(G,F)$ is defined to be the maximum number of edges in an $F$-free subgraph of $G$. Foucaud, Krivelevich and Perarnau and later independently Briggs and Cox introduced a dual version of…

Combinatorics · Mathematics 2021-01-28 Ervin Győri , Nika Salia , Casey Tompkins , Oscar Zamora

An \emph{$(n,k,t)$-graph} is a graph on $n$ vertices in which every set of $k$ vertices contains a clique on $t$ vertices. Tur\'an's Theorem, rephrased in terms of graph complements, states that the unique minimum $(n,k,2)$-graph is an…

Combinatorics · Mathematics 2025-05-19 Stacie Baumann , Joseph Briggs

In this paper, we address problems related to parameters concerning edge mappings of graphs. The quantity $h(n,G)$ is defined to be the maximum number of edges in an $n$-vertex graph $H$ such that there exists a mapping $f: E(H)\rightarrow…

Combinatorics · Mathematics 2024-02-05 Yair Caro , Balázs Patkós , Zsolt Tuza , Máté Vizer

The planar Tur\'an number of a graph $H$, denoted by $ex_{_\mathcal{P}}(n,H)$, is the largest number of edges in a planar graph on $n $ vertices without containing $H$ as a subgraph. In this paper, we continue to study the topic of…

Combinatorics · Mathematics 2022-09-07 Yongxin Lan , Zi-Xia Song

Reiher, R\"odl, Sales, and Schacht initiated the study of relative Tur\'an densities of ordered graphs and showed that it is more subtle and interesting than the unordered case. For an ordered graph $F$, its relative Tur\'an density,…

Combinatorics · Mathematics 2025-11-27 Freddie Illingworth , Arjun Ranganathan , Leo Versteegen , Ella Williams

There are various different notions measuring extremality of hypergraphs. In this survey we compare the recently introduced notion of the codegree squared extremal function with the Tur\'an function, the minimum codegree threshold and the…

Combinatorics · Mathematics 2025-01-20 József Balogh , Felix Christian Clemen , Bernard Lidický

Given two $r$-uniform hypergraphs $G$ and $H$ the Tur\'an number $\rm{ex}(G, H)$ is the maximum number of edges in an $H$-free subgraph of $G$. We study the typical value of $\rm{ex}(G, H)$ when $G=G_{n,p}^{(r)}$, the Erd\H{o}s-R\'enyi…

Combinatorics · Mathematics 2023-05-01 Dhruv Mubayi , Liana Yepremyan