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In 2017, Ron Aharoni made the following conjecture about rainbow cycles in edge-coloured graphs: If $G$ is an $n$-vertex graph whose edges are coloured with $n$ colours and each colour class has size at least $r$, then $G$ contains a…

Combinatorics · Mathematics 2022-11-22 Katie Clinch , Jackson Goerner , Tony Huynh , Freddie Illingworth

We prove the following 30-year old conjecture of Gy\H{o}ri and Tuza: the edges of every $n$-vertex graph $G$ can be decomposed into complete graphs $C_1,\ldots,C_\ell$ of orders two and three such that $|C_1|+\cdots+|C_\ell|\le…

Combinatorics · Mathematics 2019-04-03 Daniel Král' , Bernard Lidický , Taísa L. Martins , Yanitsa Pehova

An equitable $k$-coloring of a graph is a proper $k$-coloring where the sizes of any two different color classes differ by at most one. In 1973, Meyer conjectured that every connected graph $G$ has an equitable $k$-coloring for some $k\leq…

Combinatorics · Mathematics 2025-11-07 Yangyang Cheng , Zhenyu Li , Wanting Sun , Guanghui Wang

A graph $G$ is called $3$-choice critical if $G$ is not $2$-choosable but any proper subgraph is $2$-choosable. A characterization of $3$-choice critical graphs was given by Voigt in [On list Colourings and Choosability of Graphs,…

Combinatorics · Mathematics 2020-06-30 Rongxing Xu , Xuding Zhu

A seminal result by Koml\'os, Sark\"ozy, and Szemer\'edi states that if a graph $G$ with $n$ vertices has minimum degree at least $kn/(k + 1)$, for some $k \in \mathbb{N}$ and $n$ sufficiently large, then it contains the $k$-th power of a…

Combinatorics · Mathematics 2021-08-12 Rajko Nenadov , Miloš Trujić

Equitable list arboricity, introduced by Zhang in 2016, generalizes the notion of equitable list coloring by requiring the subgraph induced by each color class to be acyclic (instead of edgeless) in addition to the usual upper bound on the…

Combinatorics · Mathematics 2021-06-03 Hemanshu Kaul , Jeffrey A. Mudrock , Michael J. Pelsmajer

Graph symmetries intervene in diverse applications, from enumeration, to graph structure compression, to the discovery of graph dynamics (e.g., node arrival order inference). Whereas Erd\H{o}s-R\'enyi graphs are typically asymmetric, real…

Probability · Mathematics 2018-12-27 Tomasz Luczak , Abram Magner , Wojciech Szpankowski

A $k$-uniform tight cycle is a $k$-graph with a cyclic ordering of its vertices such that its edges are precisely the sets of $k$ consecutive vertices in that ordering. We show that, for each $k \geq 3$, the Ramsey number of the $k$-uniform…

Combinatorics · Mathematics 2025-07-03 Vincent Pfenninger

We consider the problem of finding edges of a hidden weighted graph using a certain type of queries. Let $G$ be a weighted graph with $n$ vertices. In the most general setting, the $n$ vertices are known and no other information about $G$…

Combinatorics · Mathematics 2012-01-19 Jeong Han Kim

Erd\H{o}s and Szekeres's quantitative version of Ramsey's theorem asserts that any complete graph on n vertices that is edge-colored with two colors has a monochromatic clique on at least 1/2log(n) vertices. The famous Erd\H{o}s-Hajnal…

Combinatorics · Mathematics 2021-07-30 Maria Axenovich , Richard Snyder , Lea Weber

Let $c$ be a proper edge colouring of a graph $G=(V,E)$ with integers $1,2,\ldots,k$. Then $k\geq \Delta(G)$, while by Vizing's theorem, no more than $k=\Delta(G)+1$ is necessary for constructing such $c$. On the course of investigating…

Discrete Mathematics · Computer Science 2018-03-07 Marthe Bonamy , Jakub Przybyło

In this paper we provide some exact formulas for the regularity of powers of edge ideals of vertex-weighted oriented cycles and vertex-weighted unicyclic graphs. These formulas are functions of the weight of vertices and the number of…

Commutative Algebra · Mathematics 2019-04-05 Guangjun Zhu , Hong Wang , Li Xu , Jiaqi Zhang

Let \mathcal{F}_k denote the family of 2-edge-colored complete graphs on 2k vertices in which one color forms either a clique of order k or two disjoint cliques of order k. Bollob\'as conjectured that for every \epsilon>0 and positive…

Combinatorics · Mathematics 2008-04-06 Jacob Fox , Benny Sudakov

Motivated by the exact weight perfect matching problem and recent parameterized algorithms for finding an $\ell$-th smallest perfect matching, we study structural properties of edge-weight symmetries in graphs. Recent work by El Maalouly et…

Combinatorics · Mathematics 2026-04-23 Kristóf Bérczi , Viktor Csaplár , Yutaro Yamaguchi

Bondy and Vince proved that a graph of minimum degree at least three contains two cycles whose lengths differ by one or two, which was conjectured by Erd\H{o}s. Gao, Li, Ma and Xie gave an average degree counterpart of Bondy-Vince's result,…

Combinatorics · Mathematics 2025-06-11 Binlong Li , Yufeng Pan , Lingjuan Shi

A convex geometric graph $G$ is said to be packable if there exist edge-disjoint copies of $G$ in the complete convex geometric graph $K_n$ covering all but $o(n^2)$ edges. We prove that every convex geometric graph with cyclic chromatic…

Combinatorics · Mathematics 2024-02-27 Jiaxi Nie , Erlang Surya , Ji Zeng

Given a graph $G$ and a coloring of its edges, a subgraph of $G$ is called rainbow if its edges have distinct colors. The rainbow girth of an edge coloring of G is the minimum length of a rainbow cycle in G. A generalization of the famous…

Combinatorics · Mathematics 2024-09-25 Ron Aharoni , He Guo

For a degree sequence, we define the set of edges that appear in every labeled realization of that sequence as forced, while the edges that appear in none as forbidden. We examine structure of graphs whose degree sequences contain either…

Combinatorics · Mathematics 2019-11-28 Brian Cloteaux

We consider the problem of inferring a matching hidden in a weighted random $k$-hypergraph. We assume that the hyperedges' weights are random and distributed according to two different densities conditioning on the fact that they belong to…

Disordered Systems and Neural Networks · Physics 2022-11-11 Urte Adomaityte , Anshul Toshniwal , Gabriele Sicuro , Lenka Zdeborová

There has been extensive studies on the following question: given $k$ graphs $G_1,\dots, G_k$ over a common vertex set of size $n$, what conditions on $G_i$ ensures a `colorful' copy of $H$, i.e., a copy of $H$ containing at most one edge…

Combinatorics · Mathematics 2024-01-24 Debsoumya Chakraborti , Jaehoon Kim , Hyunwoo Lee , Hong Liu , Jaehyeon Seo