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In this paper we consider a colouring version of the general position problem. The \emph{$\gp $-chromatic number} is the smallest number of colours needed to colour the vertices of the graph such that each colour class has the…

Combinatorics · Mathematics 2025-09-11 Ullas Chandran S. V. , Gabriele Di Stefano , Haritha S. , Elias John Thomas , James Tuite

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

The Bell colouring graph $\mathcal{B}(G)$ of a graph $G$ is the graph whose vertices are the partitions of the vertex set of $G$ into independent sets, with an edge between two partitions if and only if one can be obtained from the other by…

Combinatorics · Mathematics 2026-04-15 Brian Hearn

This paper analyzes the representation theoretic stability, in the sense of Thomas Church and Benson Farb, of the rank-selected homology of the Boolean lattice and the partition lattice, proving sharp uniform representation stability bounds…

Combinatorics · Mathematics 2026-05-13 Patricia Hersh , Sheila Sundaram

Topological color codes are among the stabilizer codes with remarkable properties from quantum information perspective. In this paper we construct a four-valent lattice, the so called ruby lattice, governed by a 2-body Hamiltonian. In a…

Strongly Correlated Electrons · Physics 2015-05-13 M. Kargarian , H. Bombin , M. A. Martin-Delgado

Given a graph $H$ and an integer $k\ge1$, the Gallai-Ramsey number $GR_k(H)$ is defined to be the minimum integer $n$ such that every $k$-edge coloring of $K_n$ contains either a rainbow (all different colored) triangle or a monochromatic…

Combinatorics · Mathematics 2021-07-15 Qinghong Zhao , Bing Wei

For graphs $G_1,\ldots,G_k$, the Ramsey number $R(G_1,\ldots,G_k)$ is the smallest positive integer $N$ such that every $k$-edge-coloring of $K_N$ contains a monochromatic copy of $G_i$ in color $i$ for some $i\in[k]$. The Gallai--Ramsey…

Combinatorics · Mathematics 2026-05-05 Yanbo Zhang , Qian Chen , Yaojun Chen

Dowling and Rhodes defined different lattices on the set of triples (Subset, Partition, Cross Section) over a fixed finite group G. Although the Rhodes lattice is not a geometric lattice, it defines a matroid in the sense of the theory of…

Combinatorics · Mathematics 2017-10-17 Stuart W. Margolis , John Rhodes , Pedro V. Silva

For an integer $q\ge 2$, a graph $G$ is called $q$-Ramsey for a graph $H$ if every $q$-colouring of the edges of $G$ contains a monochromatic copy of $H$. If $G$ is $q$-Ramsey for $H$, yet no proper subgraph of $G$ has this property then…

Combinatorics · Mathematics 2020-08-12 Dennis Clemens , Anita Liebenau , Damian Reding

We study quantitative aspects of the following fact: For every graph $F$, there exists a graph $G$ with the property that any $2$-coloring of the triangles of $G$ yields an induced copy of $F$, in which all triangles are monochromatic. We…

Combinatorics · Mathematics 2024-11-21 Ayush Basu , Vojtěch Rödl , Marcelo Sales

Inspired by a question of Kra, Moreira, Richter, and Robertson, we prove two new results about infinite polynomial configurations in large subsets of the rational numbers. First, given a finite coloring of $\mathbb{Q}$, we show that there…

Combinatorics · Mathematics 2025-07-08 Ethan Ackelsberg

We calculate analytically the entanglement and R\'enyi entropies, the negativity and the mutual information together with all the density and many-particle correlation functions for free bosons on a lattice in the ground state, for both…

Quantum Gases · Physics 2022-03-08 Luca Dell'Anna

For graphs $F$ and $G$, let $F\to G$ signify that any red/blue edge coloring of $F$ contains a monochromatic $G$. Denote by ${\cal G}(N,p)$ the random graph space of order $N$ and edge probability $p$. Using the regularity method, one can…

Combinatorics · Mathematics 2021-11-03 Ye Wang , Yusheng Li

We prove a theorem ensuring that the compositions of certain Ramsey families are still Ramsey. As an application, we show that in any finite coloring of $\mathbb{N}$ there is an infinite set $A$ and an as large as desired finite set $B$…

Combinatorics · Mathematics 2022-11-22 Matt Bowen

The Boolean lattice $\mathcal{P}(n)$ consists of all subsets of $[n] = \{1,\dots, n\}$ partially ordered under the containment relation. Sperner's Theorem states that the largest antichain of the Boolean lattice is given by a middle layer:…

Combinatorics · Mathematics 2023-09-22 József Balogh , Robert A. Krueger

The Ramsey number $R_X(p,q)$ for a class of graphs $X$ is the minimum $n$ such that every graph in $X$ with at least $n$ vertices has either a clique of size $p$ or an independent set of size $q$. We say that Ramsey numbers are linear in…

Combinatorics · Mathematics 2020-12-07 Bogdan Alecu , Aistis Atminas , Vadim Lozin , Viktor Zamaraev

A resolving set for a graph $G$ is a set of vertices $Q = \{q_1, ..., q_k\}$ such that, for all $p\in V(G)$ the $k$-tuple $(d(p, q_1), ..., d(p, q_k ))$ uniquely determines $p$, where $d(p, q_i)$ is considered as the minimum length of a…

Combinatorics · Mathematics 2024-07-30 Ali Zafari , Saeid Alikhani

For two graphs $G$ and $H$, write $G \stackrel{\mathrm{rbw}}{\longrightarrow} H$ if $G$ has the property that every \emph{proper} colouring of its edges yields a \emph{rainbow} copy of $H$. We study the thresholds for such so-called…

Combinatorics · Mathematics 2022-07-18 Elad Aigner-Horev , Oran Danon , Dan Hefetz , Shoham Letzter

The canonical van der Waerden theorem asserts that, for sufficiently large $n$, every colouring of $[n]$ contains either a monochromatic or a rainbow arithmetic progression of length $k$ ($k$-AP, for short). In this paper, we determine the…

Combinatorics · Mathematics 2026-04-28 José D. Alvarado , Yoshiharu Kohayakawa , Patrick Morris , Guilherme O. Mota , Miquel Ortega

For a graph $H$ and an integer $k\ge1$, the $k$-color Ramsey number $R_k(H)$ is the least integer $N$ such that every $k$-coloring of the edges of the complete graph $K_N$ contains a monochromatic copy of $H$. Let $C_m$ denote the cycle on…

Combinatorics · Mathematics 2020-09-18 Fangfang Zhang , Zi-Xia Song , Yaojun Chen