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We study the existence of powers of Hamiltonian cycles in graphs with large minimum degree to which some additional edges have been added in a random manner. It follows from the theorems of Dirac and of Koml\'os, Sark\"ozy, and Szemer\'edi…

Combinatorics · Mathematics 2020-05-26 Andrzej Dudek , Christian Reiher , Andrzej Ruciński , Mathias Schacht

The Graph Reconstruction Conjecture famously posits that any undirected graph on at least three vertices is determined up to isomorphism by its family of (unlabeled) induced subgraphs. At present, the conjecture admits partial resolutions…

Discrete Mathematics · Computer Science 2025-12-03 Julian Asilis , Xi Chen , Dutch Hansen , Shang-Hua Teng

We discuss a variant of the Ramsey and the directed Ramsey problem. First, consider a complete graph on $n$ vertices and a two-coloring of the edges such that every edge is colored with at least one color and the number of bicolored edges…

Combinatorics · Mathematics 2016-01-22 Zoltán Lóránt Nagy

The $\mathcal{D}$-process is a single player game in which the player is initially presented the empty graph on $n$ vertices. In each step, a subset of edges $X$ is independently sampled according to a distribution $\mathcal{D}$. The player…

Combinatorics · Mathematics 2023-10-27 Calum MacRury , Erlang Surya

Sidorenko's Conjecture asserts that every bipartite graph H has the Sidorenko property, i.e., a quasirandom graph minimizes the density of H among all graphs with the same edge density. We study a stronger property, which requires that a…

Combinatorics · Mathematics 2019-12-10 Daniel Král' , Taísa Martins , Péter Pál Pach , Marcin Wrochna

For a positive integer $k$ and a graph $H$ on $k$ vertices, we are interested in the inducibility of $H$, denoted $\mathrm{ind}(H)$, which is defined as the maximum possible probability that choosing $k$ vertices uniformly at random from a…

Combinatorics · Mathematics 2024-11-27 Richard Ueltzen

We confirm the eventual evasiveness of several classes of monotone graph properties under widely accepted number theoretic hypotheses. In particular we show that Chowla's conjecture on Dirichlet primes implies that (a) for any graph $H$,…

Computational Complexity · Computer Science 2010-02-03 Laszlo Babai , Anandam Banerjee , Raghav Kulkarni , Vipul Naik

An ordered graph $H$ on $n$ vertices is a graph whose vertices have been labeled bijectively with $\{1,...,n\}$. The ordered Ramsey number $r_<(H)$ is the minimum $n$ such that every two-coloring of the edges of the complete graph $K_n$…

Combinatorics · Mathematics 2019-10-31 Will Overman , Jeremy F. Alm , Kayla Coffey , Carolyn Langhoff

A tuple $(G_1,\dots,G_n)$ of graphs on the same vertex set of size $n$ is said to be Hamilton-universal if for every map $\chi: [n]\to[n]$ there exists a Hamilton cycle whose $i$-th edge comes from $G_{\chi(i)}$. Bowtell, Morris, Pehova and…

Combinatorics · Mathematics 2026-02-26 Micha Christoph , Anders Martinsson , Aleksa Milojević

In this paper, we prove tight sufficient conditions for traceability and Hamiltonicity of connected graphs with given minimum degree, in terms of Wiener index and Harary index. We also prove some result on Hamiltonicity of balanced…

Combinatorics · Mathematics 2017-01-30 Hongbo Hua , Bo Ning

Order the vertices of a directed random graph \math{v_1,...,v_n}; edge \math{(v_i,v_j)} for \math{i<j} exists independently with probability \math{p}. This random graph model is related to certain spreading processes on networks. We…

Combinatorics · Mathematics 2012-09-12 Paul Horn , Malik Magdon-Ismail

A graph $G$ is called a $2K_2$-free graph if it does not contain $2K_2$ as an induced subgraph. In 2014, Broersma, Patel and Pyatkin showed that every 25-tough $2K_2$-free graph on at least three vertices is Hamiltonian. Recently, Shan…

Combinatorics · Mathematics 2021-12-06 Katsuhiro Ota , Masahiro Sanka

Given a symmetric $n\times n$ matrix $P$ with $0 \le P(u, v)\le 1$, we define a random graph $G_{n, P}$ on $[n]$ by independently including any edge $\{u, v\}$ with probability $P(u, v)$. For $k\ge 1$ let $\mathcal{A}_k$ be the property of…

Combinatorics · Mathematics 2020-12-23 Tony Johansson

A bipartite graph on 2n vertices is bipancyclic if it contains cycles of all even lengths from 4 to 2n. In this paper we prove that the random bipartite graph $G(n,n,p)$ with $p(n)\gg n^{-2/3}$ asymptotically almost surely has the following…

Combinatorics · Mathematics 2012-12-17 Yilun Shang

Let $r\ge 3$ be a fixed constant and let $ {\mathcal H}$ be an $r$-uniform, $D$-regular hypergraph on $N$ vertices. Assume further that $ D > N^\varepsilon $ for some $ \varepsilon>0 $. Consider the random greedy algorithm for forming an…

Combinatorics · Mathematics 2024-09-25 Patrick Bennett , Tom Bohman

A conjecture of Carsten Thomassen states that every 4-connected line graph is hamiltonian. It is known that the conjecture is true for 7-connected line graphs. We improve this by showing that any 5-connected line graph of minimum degree at…

Combinatorics · Mathematics 2011-04-01 Tomáš Kaiser , Petr Vrána

When each vertex is assigned a set, the intersection graph generated by the sets is the graph in which two distinct vertices are joined by an edge if and only if their assigned sets have a nonempty intersection. An interval graph is an…

Combinatorics · Mathematics 2017-02-13 Jeong Han Kim , Sang June Lee , Joohan Na

We prove a new generalisation of Ramsey's theorem by showing that every $2$-edge-coloured graph with sufficiently large minimum degree contains a monochromatic induced subgraph whose minimum degree remains large. From this, we also derive…

Combinatorics · Mathematics 2026-04-17 Arnab Char , Ken-ichi Kawarabayashi , Lucas Picasarri-Arrieta

Given a graph $G$ and an $r$-edge-colouring $\chi$ on $E(G)$, a Hamilton cycle $H\subset G$ is said to have $t$ colour-bias if $H$ contains $n/r+t$ edges of the same colour in $\chi$. Freschi, Hyde, Lada and Treglown showed every…

Combinatorics · Mathematics 2025-06-05 Wenchong Chen , Xinbu Cheng , Zhifei Yan

A graph on $n$ vertices is said to be \emph{$C$-Ramsey} if every clique or independent set of the graph has size at most $C \log n$. The only known constructions of Ramsey graphs are probabilistic in nature, and it is generally believed…

Combinatorics · Mathematics 2017-09-08 Bhargav Narayanan , Julian Sahasrabudhe , István Tomon
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