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Related papers: Robust hamiltonicity of random directed graphs

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An $n$-vertex graph $G$ is a $C$-expander if $|N(X)|\geq C|X|$ for every $X\subseteq V(G)$ with $|X|< n/2C$ and there is an edge between every two disjoint sets of at least $n/2C$ vertices. We show that there is some constant $C>0$ for…

Erd\H{o}s conjectured that every $n$-vertex triangle-free graph contains a subset of $\lfloor n/2\rfloor$ vertices that spans at most $n^2/50$ edges. Extending a recent result of Norin and Yepremyan, we confirm this conjecture for graphs…

Combinatorics · Mathematics 2019-03-05 Wiebke Bedenknecht , Guilherme Oliveira Mota , Christian Reiher , Mathias Schacht

We provide a combinatorial characterization of all testable properties of $k$-uniform hypergraphs ($k$-graphs for short). Here, a $k$-graph property $P$ is testable if there is a randomized algorithm which makes a bounded number of edge…

Combinatorics · Mathematics 2025-05-08 Felix Joos , Jaehoon Kim , Daniela Kühn , Deryk Osthus

We prove measurable analogues of Whitney's classical theorems on weak isomorphisms of finite graphs. In the setting of locally finite graphings, we introduce a notion of weak isomorphism as an edge-measure-preserving Borel bijection that…

Combinatorics · Mathematics 2026-05-18 Márton Borbényi , Grigory Terlov , László Márton Tóth

Two major milestones on the road to the full complexity dichotomy for finite-domain constraint satisfaction problems were Bulatov's proof of the dichotomy for conservative templates, and the structural dichotomy for smooth digraphs of…

Logic in Computer Science · Computer Science 2026-04-07 Johanna Brunar , Marcin Kozik , Tomáš Nagy , Michael Pinsker

We show that a $k$-uniform hypergraph on $n$ vertices has a spanning subgraph homeomorphic to the $(k - 1)$-dimensional sphere provided that $H$ has no isolated vertices and each set of $k - 1$ vertices supported by an edge is contained in…

Combinatorics · Mathematics 2025-06-17 Freddie Illingworth , Richard Lang , Alp Müyesser , Olaf Parczyk , Amedeo Sgueglia

We prove a conjecture of Penrose about the standard random geometric graph process, in which n vertices are placed at random on the unit square and edges are sequentially added in increasing order of lengths taken in the l_p norm. We show…

Combinatorics · Mathematics 2009-07-28 Xavier Pérez-Giménez , Nicholas C. Wormald

In 1952, Dirac proved that every $2$-connected $n$-vertex graph with the minimum degree $k+1$ contains a cycle of length at least $\min\{n, 2(k+1)\}$. Here we obtain a stability version of this result by characterizing those graphs with…

Combinatorics · Mathematics 2022-08-04 Xiutao Zhu , Ervin Győri , Zhen He , Zequn Lv , Nika Salia , Chuanqi Xiao

A well known theorem in graph theory states that every graph $G$ on $n$ vertices and minimum degree at least $d$ contains a path of length at least $d$, and if $G$ is connected and $n\ge 2d+1$ then $G$ contains a path of length at least…

Combinatorics · Mathematics 2019-03-12 Yue Ma , Xinmin Hou , Jun Gao

A graph is said to be $\mathcal{H}(n, \Delta)$-universal if it contains every graph on $n$ vertices with maximum degree at most $\Delta$. Using a `matching-based' embedding technique introduced by Alon and F\"uredi, Dellamonica, Kohayakawa,…

Combinatorics · Mathematics 2017-07-26 Asaf Ferber , Rajko Nenadov

A graph is called $2K_2$-free if it does not contain two independent edges as an induced subgraph. Broersma, Patel, and Pyatkin showed that every 25-tough $2K_2$-free graph with at least three vertices is hamiltonian. In this paper, we…

Combinatorics · Mathematics 2017-06-29 Songling Shan

Reed's $\omega$, $\Delta$, $\chi$ conjecture proposes that every graph satisfies $\chi\leq \lceil\frac 12(\Delta+1+\omega)\rceil$; it is known to hold for all claw-free graphs. In this paper we consider a local strengthening of this…

Discrete Mathematics · Computer Science 2011-11-30 Maria Chudnovsky , Andrew D. King , Matthieu Plumettaz , Paul Seymour

Persistent homology is a popular method for computing topological features of (metric) data. Standard approaches based on the \v{C}ech or Rips filtration are stable under small perturbations of the data, but highly sensitive to outliers.…

Algebraic Topology · Mathematics 2026-02-27 Pepijn Roos Hoefgeest , Lucas Slot

In a sequence of four papers, we prove the following results (via a unified approach) for all sufficiently large $n$: (i) [1-factorization conjecture] Suppose that $n$ is even and $D \geq 2\lceil n/4\rceil -1$. Then every $D$-regular graph…

Combinatorics · Mathematics 2014-10-24 Béla Csaba , Daniela Kühn , Allan Lo , Deryk Osthus , Andrew Treglown

Let $G$ be a graph on $n\geq 3$ vertices, claw the bipartite graph $K_{1,3}$, and $Z_i$ the graph obtained from a triangle by attaching a path of length $i$ to its one vertex. $G$ is called 1-heavy if at least one end vertex of each induced…

Combinatorics · Mathematics 2013-01-07 Bo Ning , Bing Chen , Shenggui Zhang

We consider random graphs in which the edges are allowed to be dependent. In our model the edge dependence is quite general, we call it $p$-robust random graph. It means that every edge is present with probability at least $p$, regardless…

Discrete Mathematics · Computer Science 2020-12-04 Zohre Ranjbar-Mojaveri , Andras Farago

Random intersection graphs have received much attention for nearly two decades, and currently have a wide range of applications ranging from key predistribution in wireless sensor networks to modeling social networks. In this paper, we…

Discrete Mathematics · Computer Science 2016-11-15 Jun Zhao , Osman Yağan , Virgil Gligor

Consider a graph $G=(V,E)$ without isolated edges and with maximum degree $\Delta$. Given a colouring $c:E\to\{1,2,\ldots,k\}$, the weighted degree of a vertex $v\in V$ is the sum of its incident colours, i.e., $\sum_{e\ni v}c(e)$. For any…

Combinatorics · Mathematics 2018-03-13 Jakub Przybyło

This article introduces and studies a new class of graphs motivated by discrete curvature. We call a graph resistance nonnegative if there exists a distribution on its spanning trees such that every vertex has expected degree at most two in…

Combinatorics · Mathematics 2025-08-08 Karel Devriendt

Consider the uniform random graph $G(n,M)$ with $n$ vertices and $M$ edges. Erd\H{o}s and R\'enyi (1960) conjectured that the limit $$ \lim_{n \to \infty} \Pr\{G(n,\textstyle{n\over 2}) is planar}} $$ exists and is a constant strictly…

Combinatorics · Mathematics 2012-05-01 Marc Noy , Vlady Ravelomanana , Juanjo Rué
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