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A well-known open problem on the behavior of optimal paths in random graphs in the strong disorder regime, formulated by statistical physicists, and supported by a large amount of numerical evidence over the last decade [31,32,38,70] is as…

Probability · Mathematics 2024-01-15 Shankar Bhamidi , Sanchayan Sen

Given an $r$-graph $F$ with $r \ge 2$, let $\mathrm{ex}(n, (t+1) F)$ denote the maximum number of edges in an $n$-vertex $r$-graph with at most $t$ pairwise vertex-disjoint copies of $F$. Extending several old results and complementing…

Combinatorics · Mathematics 2024-10-15 Jianfeng Hou , Caiyun Hu , Heng Li , Xizhi Liu , Caihong Yang , Yixiao Zhang

The degree diameter problem asks for the maximum possible number of vertices in a graph of maximum degree $\Delta$ and diameter $D$. In this paper, we focus on planar graphs of diameter $3$. Fellows, Hell and Seyffarth (1995) proved that…

Combinatorics · Mathematics 2025-07-28 Antoine Dailly , Sasha Darmon , Ugo Giocanti , Claire Hilaire , Petru Valicov

Let G=(V,E) be a graph with f:V\to Z_+ a function assigning degree bounds to vertices. We present the first efficient algebraic algorithm to find an f-factor. The time is \tilde{O}(f(V)^{\omega}). More generally for graphs with integral…

Data Structures and Algorithms · Computer Science 2013-04-26 Harold N. Gabow , Piotr Sankowski

The hypergraph regularity lemma -- the extension of Szemer\'edi's graph regularity lemma to the setting of $k$-uniform hypergraphs -- is one of the most celebrated combinatorial results obtained in the past decade. By now there are several…

Combinatorics · Mathematics 2019-07-18 Guy Moshkovitz , Asaf Shapira

Covering numbers are a powerful tool used in the development of approximation algorithms, randomized dimension reduction methods, smoothed complexity analysis, and others. In this paper we prove upper bounds on the covering number of…

Algebraic Geometry · Mathematics 2025-06-09 Yifan Zhang , Joe Kileel

In this paper we investigate Ramanujan hypergraphs by using hypergraph coverings. We first show that the spectrum of a $k$-fold covering $\bar{H}$ of a connected hypergraph $H$ contains the spectrum of $H$, and that it is the union of the…

Combinatorics · Mathematics 2024-03-05 Yi-Min Song , Yi-Zheng Fan , Zhengke Miao

Geometrization says `` any closed oriented three-manifold which is prime (not a connected sum) carries one of the eight Thurston geometries OR it has incompressible torus walls whose complementary components each carry one of four…

Geometric Topology · Mathematics 2023-09-06 Alice Kwon , Dennis Sullivan

In this paper we give a f-approximation algorithm for the minimum unweighted Vertex Cover problem with Hard Capacity constraints (VCHC) on f-hypergraphs. This problem generalizes standard vertex cover for which the best known approximation…

Data Structures and Algorithms · Computer Science 2017-01-24 Sam Chiu-wai Wong

We show that for sufficiently large $d$ and for $t\geq d+1$, there is a graph $G$ with average degree $(1-\varepsilon)\lambda t \sqrt{\ln d}$ such that almost every graph $H$ with $t$ vertices and average degree $d$ is not a minor of $G$,…

Combinatorics · Mathematics 2020-12-14 Sergey Norin , Bruce Reed , Andrew Thomason , David R. Wood

For any $\epsilon > 0$, we show that if $G$ is a regular graph on $n \gg_\epsilon 1$ vertices that is $\epsilon$-far (differs by at least $\epsilon n^2$ edges) from any Tur\'{a}n graph, then its second eigenvalue $\lambda_2$ satisfies…

Combinatorics · Mathematics 2025-07-15 Shengtong Zhang

Let $G=(V,E)$ be a $\tau$-critical graph with $\tau(G)=t$. Erd\H{o}s and Gallai proved that $|V|\leq 2t$ and the bound $|E|\leq {t+1\choose 2}$ was obtained by Erd\H{o}s, Hajnal and Moon. We give here the sharp combined bound $|E|+|V|\leq…

Combinatorics · Mathematics 2019-08-15 Andras Gyarfas , Lehel Jeno

The hypergraph regularity lemma -- the extension of Szemer\'edi's graph regularity lemma to the setting of $k$-uniform hypergraphs -- is one of the most celebrated combinatorial results obtained in the past decade. By now there are several…

Combinatorics · Mathematics 2019-07-19 Guy Moshkovitz , Asaf Shapira

An $\mathcal{F}$-saturated $r$-graph is a maximal $r$-graph not containing any member of $\mathcal{F}$ as a subgraph. Let $\mathcal{K}_{\ell + 1}^{r}$ be the collection of all $r$-graphs $F$ with at most $\binom{\ell+1}{2}$ edges such that…

Combinatorics · Mathematics 2022-11-08 Jianfeng Hou , Heng Li , Caihong Yang , Qinghou Zeng , Yixiao Zhang

We consider list-decoding in the zero-rate regime for two cases: the binary alphabet and the spherical codes in Euclidean space. Specifically, we study the maximal $\tau \in [0,1]$ for which there exists an arrangement of $M$ balls of…

Information Theory · Computer Science 2018-05-15 Noga Alon , Boris Bukh , Yury Polyanskiy

We study $\tau$-Bounded-Density Edge Deletion ($\tau$-BDED), where given an undirected graph $G$, the task is to remove as few edges as possible to obtain a graph $G'$ where no subgraph of $G'$ has density more than $\tau$. The density of a…

Data Structures and Algorithms · Computer Science 2026-01-07 Matthias Bentert , Tom-Lukas Breitkopf , Vincent Froese , Anton Herrmann , André Nichterlein

Fix $k \geq 3$, and let $G$ be a $k$-uniform hypergraph with maximum degree $\Delta$. Suppose that for each $l = 2, ..., k-1$, every set of l vertices of G is in at most $\Delta^{(k-l)/(k-1)}/f$ edges. Then the chromatic number of $G$ is…

Combinatorics · Mathematics 2014-04-11 Jeff Cooper , Dhruv Mubayi

We show that for every $n$-vertex graph with at least one edge, its treewidth is greater than or equal to $n \lambda_{2} / (\Delta + \lambda_{2}) - 1$, where $\Delta$ and $\lambda_{2}$ are the maximum degree and the second smallest…

Combinatorics · Mathematics 2024-04-15 Tatsuya Gima , Tesshu Hanaka , Kohei Noro , Hirotaka Ono , Yota Otachi

Given a weighted hypergraph $\mathcal{H}(V, \mathcal{E} \subseteq 2^V, w)$, the approximate $k$-cover problem seeks for a size-$k$ subset of $V$ that has the maximum weighted coverage by \emph{sampling only a few hyperedges} in…

Social and Information Networks · Computer Science 2019-01-24 Hung Nguyen , Phuc Thai , My Thai , Tam Vu , Thang Dinh

We consider the performance of the Depth First Search (DFS) algorithm on the random graph $G\left(n,\frac{1+\epsilon}{n}\right)$, $\epsilon>0$ a small constant. Recently, Enriquez, Faraud and M\'enard [2] proved that the stack $U$ of the…

Combinatorics · Mathematics 2022-07-27 Sahar Diskin , Michael Krivelevich
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