English
Related papers

Related papers: Integer colorings with forbidden rainbow sums

200 papers

A ring is a graph $R$ whose vertex set can be partitioned into $k \geq 4$ nonempty sets, $X_1, \dots, X_k$, such that for all $i \in \{1,\dots,k\}$, the set $X_i$ can be ordered as $X_i = \{u_i^1, \dots, u_i^{|X_i|}\}$ so that $X_i…

Combinatorics · Mathematics 2020-09-21 Frédéric Maffray , Irena Penev , Kristina Vušković

We show that for any integer $k\ge 1$ there exists an integer $t_0(k)$ such that for integers $t, k_1, \ldots, k_{t+1}, n$ with $t>t_0(k)$, $\max\{k_1, \ldots, k_{t+1}\}\le k$, and $n > 2k(t+1)$, the following holds: If $F_i \subseteq…

Combinatorics · Mathematics 2026-02-25 Hongliang Lu , Yan Wang , Xingxing Yu

We say that an edge-coloring of a graph $G$ is proper if every pair of incident edges receive distinct colors, and is rainbow if no two edges of $G$ receive the same color. Furthermore, given a fixed graph $F$, we say that $G$ is rainbow…

Combinatorics · Mathematics 2026-02-19 Anastasia Halfpap , Bernard Lidický , Tomáš Masařík

We show that for any nonnegative integer $r$, the Weighted Maximum List-$k$-Colourable Induced Subgraph problem can be solved in polynomial time for input graphs that do not contain $(P_5+ rK_1)$ as an induced subgraph, and give an explicit…

Combinatorics · Mathematics 2025-11-17 Cicely Henderson , Evelyne Smith-Roberge , Sophie Spirkl , Rebecca Whitman

In this paper, we generalize the concepts related to rainbow coloring to hypergraphs. Specifically, an $(n,r,H)$-local coloring is defined as a collection of $n$ edge-colorings, $f_v: E(K^{(r)}_n) \rightarrow [k]$ for each vertex $v$ in the…

Combinatorics · Mathematics 2025-05-13 Zhenyu Li , Weichan Liu , Guowei Sun , Xia Wang , Shunan Wei

We prove a known 2-coloring of the integers $[N] := \{1,2,3,\ldots,N\}$ minimizes the number of monochromatic arithmetic 3-progressions under certain restrictions. A monochromatic arithmetic progression is a set of equally-spaced integers…

Combinatorics · Mathematics 2023-01-03 Torin Greenwood , Jonathan Kariv , Noah Williams

We define the problem as a two-player game between Algorithm and Builder. The game is played in rounds. Each round, Builder presents an interval that is neither contained in nor contains any previously presented interval. Algorithm…

Combinatorics · Mathematics 2025-02-26 Israel R. Curbelo , Hannah R. Malko

A finite set $A$ of integers is square-sum-free if there is no subset of $A$ sums up to a square. In 1986, Erd\H os posed the problem of determining the largest cardinality of a square-sum-free subset of $\{1, ..., n \}$. Answering this…

Combinatorics · Mathematics 2009-10-30 Hoi Nguyen , Van Vu

Let $k$ and $n$ be two integers, with $k\geq 3$, $n\equiv 0\pmod k$, and $n$ sufficiently large. We determine the $(k-1)$-degree threshold for the existence of a rainbow perfect matchings in $n$-vertex $k$-uniform hypergraph. This implies…

Combinatorics · Mathematics 2021-11-02 Hongliang Lu , Yan Wang , Xingxing Yu

An edge-coloring of a graph $G$ with natural numbers is called a sum edge-coloring if the colors of edges incident to any vertex of $G$ are distinct and the sum of the colors of the edges of $G$ is minimum. The edge-chromatic sum of a graph…

Combinatorics · Mathematics 2012-11-26 P. A. Petrosyan , R. R. Kamalian

The canonical Ramsey theorem of Erd\H{o}s and Rado implies that for any graph $H$, any edge-coloring (with an arbitrary number of colors) of a sufficiently large complete graph $K_N$ contains a monochromatic, lexicographic, or rainbow copy…

Combinatorics · Mathematics 2024-10-14 Lior Gishboliner , Aleksa Milojević , Benny Sudakov , Yuval Wigderson

We prove that any family $E_1, \ldots , E_{\lceil rn \rceil}$ of (not necessarily distinct) sets of edges in an $r$-uniform hypergraph, each having a fractional matching of size $n$, has a rainbow fractional matching of size $n$ (that is, a…

Combinatorics · Mathematics 2020-01-27 Ron Aharoni , Ron Holzman , Zilin Jiang

Alon and Shikhelman initiated the systematic study of the following generalized Tur\'an problem: for fixed graphs $H$ and $F$ and an integer $n$, what is the maximum number of copies of $H$ in an $n$-vertex $F$-free graph? An edge-colored…

Combinatorics · Mathematics 2019-11-18 Dániel Gerbner , Tamás Mészáros , Abhishek Methuku , Cory Palmer

Given an edge-coloured graph, we say that a subgraph is rainbow if all of its edges have different colours. Let $\operatorname{ex}(n,H,$rainbow-$F)$ denote the maximal number of copies of $H$ that a properly edge-coloured graph on $n$…

Combinatorics · Mathematics 2022-02-28 Barnabás Janzer

We give asymptotically optimal constructions in generalized Ramsey theory using results about conflict-free hypergraph matchings. For example, we present an edge-coloring of $K_{n,n}$ with $2n/3 + o(n)$ colors such that each $4$-cycle…

Combinatorics · Mathematics 2022-08-29 Felix Joos , Dhruv Mubayi

In their 1997 paper titled ``Fruit Salad", Gy\'{a}rf\'{a}s posed the following conjecture: there exists a constant $k$ such that if each path of a graph spans a $3$-colourable subgraph, then the graph is $k$-colourable. It is noted that…

Combinatorics · Mathematics 2025-06-25 Ben Cameron , Alexander Clow

A conjecture of the first two authors is that $n$ matchings of size $n$ in any graph have a rainbow matching of size $n-1$. We prove a lower bound of $\frac{2}{3}n-1$, improving on the trivial $\frac{1}{2}n$, and an analogous result for…

Combinatorics · Mathematics 2021-10-08 Ron Aharoni , Eli Berger , Maria Chudnovsky , Shira Zerbib

The multicolor Ramsey number problem asks, for each pair of natural numbers $\ell$ and $t$, for the largest $\ell$-coloring of a complete graph with no monochromatic clique of size $t$. Recent works of Conlon-Ferber and Wigderson have…

Combinatorics · Mathematics 2021-11-23 Will Sawin

Let $G$ be a graph of order $n$ with an edge-coloring $c$, and let $\delta^c(G)$ denote the minimum color degree of $G$. A subgraph $F$ of $G$ is called rainbow if all edges of $F$ have pairwise distinct colors. There have been a lot…

Combinatorics · Mathematics 2020-10-23 Xiaozheng Chen , Xueliang Li

For a graph with colored vertices, a rainbow subgraph is one where all vertices have different colors. For graph $G$, let $c_k(G)$ denote the maximum number of different colors in a coloring without a rainbow path on $k$ vertices, and…

Combinatorics · Mathematics 2025-01-03 Wayne Goddard , Tyler Herrman , Simon J. Hughes