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Given a graph $H$, a balanced subdivision of $H$ is a graph obtained from $H$ by subdividing every edge the same number of times. In 1984, Thomassen conjectured that for each integer $k\ge 1$, high average degree is sufficient to guarantee…

Combinatorics · Mathematics 2023-02-21 Bingyu Luan , Yantao Tang , Guanghui Wang , Donglei Yang

The codegree threshold $\mathrm{ex}_2(n, F)$ of a $3$-graph $F$ is the minimum $d=d(n)$ such that every $3$-graph on $n$ vertices in which every pair of vertices is contained in at least $d+1$ edges contains a copy of $F$ as a subgraph. We…

Combinatorics · Mathematics 2022-12-22 Victor Falgas-Ravry , Oleg Pikhurko , Emil R. Vaughan , Jan Volec

Finding dense subgraphs in a graph is a fundamental graph mining task, with applications in several fields. Algorithms for identifying dense subgraphs are used in biology, in finance, in spam detection, etc. Standard formulations of this…

Data Structures and Algorithms · Computer Science 2018-07-10 G. Nikolentzos , P. Meladianos , Y. Stavrakas , M. Vazirgiannis

Let $K\_{[k,t]}$ be the complete graph on $k$ vertices from which a set of edges, induced by a clique of order $t$, has been dropped. In this note we give two explicit upper bounds for $R(K\_{[k\_1,t\_1]},\dots, K\_{[k\_r,t\_r]})$ (the…

Combinatorics · Mathematics 2014-12-15 Jonathan Chappelon , Luis Pedro Montejano , Jorge Luis Ramírez Alfonsín

We consider the problem of space-efficiently estimating the number of simplices in a hypergraph stream. This is the most natural hypergraph generalization of the highly-studied problem of estimating the number of triangles in a graph…

Data Structures and Algorithms · Computer Science 2021-12-22 Amit Chakrabarti , Themistoklis Haris

For a $k$-uniform hypergraph (or simply $k$-graph) $F$, the codegree Tur\'{a}n density $\pi_{\mathrm{co}}(F)$ is the infimum over all $\alpha$ such that any $n$-vertex $k$-graph $H$ with every $(k-1)$-subset of $V(H)$ contained in at least…

Combinatorics · Mathematics 2023-12-06 Laihao Ding , Hong Liu , Shuaichao Wang , Haotian Yang

We give a simple method to estimate the number of distinct copies of some classes of spanning subgraphs in hypergraphs with high minimum degree. In particular, for each $k\geq 2$ and $1\leq \ell\leq k-1$, we show that every $k$-graph on $n$…

Combinatorics · Mathematics 2024-11-20 Richard Montgomery , Matías Pavez-Signé

We provide an algorithm that verifies the optimal colored Tverberg problem for $10$ points in the plane: Every $10$ points in the plane in color classes of size at most $3$ can be partitioned in $4$ rainbow pieces such that their convex…

Combinatorics · Mathematics 2022-03-28 Jonathan Kliem

Our main result improves bounds of Markstrom and Rucinski on the minimum d-degree which forces a perfect matching in a k-uniform hypergraph on n vertices. We also extend bounds of Bollobas, Daykin and Erdos by asymptotically determining the…

Combinatorics · Mathematics 2013-12-03 Daniela Kühn , Deryk Osthus , Timothy Townsend

For an integer $k\ge 3$, a $k$-path vertex cover of a graph $G=(V,E)$ is a set $T\subseteq V$ that shares a vertex with every path subgraph of order $k$ in $G$. The minimum cardinality of a $k$-path vertex cover is denoted by $\psi_k(G)$.…

Combinatorics · Mathematics 2021-05-06 Csilla Bujtás , Marko Jakovac , Zsolt Tuza

A $k$-edge-coloured graph is colour-balanced if each colour appears equally often. Resolving a conjecture of Pardey and Rautenbach, we show that any colour-balanced $k$-edge-coloured complete graph $K_{2kt}$ contains a perfect matching that…

Combinatorics · Mathematics 2026-04-13 Emma Hogan , Alex Scott , Dmitry Tsarev

For a graph G, the k-total dominating graph D_{k}^{t}(G) is the graph whose vertices correspond to the total dominating sets of G that have cardinality at most k; two vertices of D_{k}^{t}(G) are adjacent if and only if the corresponding…

Combinatorics · Mathematics 2017-11-17 Saeid Alikhani , Davood Fatehi , Kieka Mynhardt

A $k$-graph (or $k$-uniform hypergraph) $H$ is uniformly dense if the edge distribution of $H$ is uniformly dense with respect to every large collection of $k$-vertex cliques induced by sets of $(k-2)$-tuples. Reiher, R\"odl and Schacht…

Combinatorics · Mathematics 2023-05-03 Hao Lin , Guanghui Wang , Wenling Zhou

If each edge (u,v) of a graph G=(V,E) is decorated with a permutation pi_{u,v} of k objects, we say that it has a permuted k-coloring if there is a coloring sigma from V to {1,...,k} such that sigma(v) is different from pi_{u,v}(sigma(u))…

Combinatorics · Mathematics 2011-11-16 Varsha Dani , Cristopher Moore , Anna Olson

Given a graph $G$, a \textit{$k$-total difference labeling} of the graph is a total labeling $f$ from the set of edges and vertices to the set $\{1, 2, \cdots k\}$ satisfying that for any edge $\{u,v\}$, $f(\{u,v\})=|f(u)-f(v)|$. If $G$ is…

A proper total colouring of a graph $G$ is called harmonious if it has the further property that when replacing each unordered pair of incident vertices and edges with their colours, then no pair of colours appears twice. The smallest…

Combinatorics · Mathematics 2024-01-19 M. Abreu , J. B. Gauci , D. Mattiolo , G. Mazzuoccolo , F. Romaniello , C. Rubio-Montiel , T. Traetta

We show that for all $k\geq 4$, $\varepsilon >0$, and $n$ sufficiently large, every $k$-uniform hypergraph on $n$ vertices in which each set of $k-3$ vertices is contained in at least $(5/8 + \varepsilon) \binom{n}{3}$ edges contains a…

Combinatorics · Mathematics 2025-07-31 Richard Lang , Mathias Schacht , Jan Volec

The codegree Tur\'an density $\gamma(F)$ of a $k$-uniform hypergraph $F$ is the minimum real number $\gamma \ge 0$ such that every $k$-uniform hypergraph on sufficiently many $n$ vertices, in which every set of $k-1$ vertices is contained…

Combinatorics · Mathematics 2025-12-30 Jie Ma , Mingyuan Rong

A star $k$-edge coloring is a proper edge coloring such that there are no bichromatic paths or cycles of length four. The smallest integer $k$ such that $G$ admits a star $k$-edge coloring is the star chromatic index of $G$. Deng \etal…

Combinatorics · Mathematics 2021-06-22 Zhengke Miao , Yimin Song , Tao Wang , Xiaowei Yu

We study the following problem: given an integer $k \ge 3$ and a simple graph $G$, sample a connected induced $k$-node subgraph of $G$ uniformly at random. This is a fundamental graph mining primitive with applications in social network…

Data Structures and Algorithms · Computer Science 2021-10-29 Marco Bressan