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We develop a notion of containment for independent sets in hypergraphs. For every $r$-uniform hypergraph $G$, we find a relatively small collection $C$ of vertex subsets, such that every independent set of $G$ is contained within a member…

Combinatorics · Mathematics 2014-12-01 David Saxton , Andrew Thomason

We consider the problem of enumerating optimal solutions for two hypergraph $k$-partitioning problems -- namely, Hypergraph-$k$-Cut and Minmax-Hypergraph-$k$-Partition. The input in hypergraph $k$-partitioning problems is a hypergraph…

Data Structures and Algorithms · Computer Science 2023-03-09 Calvin Beideman , Karthekeyan Chandrasekaran , Weihang Wang

We consider straight line drawings of a planar graph $G$ with possible edge crossings. The \emph{untangling problem} is to eliminate all edge crossings by moving as few vertices as possible to new positions. Let $fix(G)$ denote the maximum…

Computational Geometry · Computer Science 2011-11-14 Alexander Ravsky , Oleg Verbitsky

Given a graph $G=(V,E)$, a set $\mathcal{F}$ of forbidden subgraphs, we study $\mathcal{F}$-Free Edge Deletion, where the goal is to remove minimum number of edges such that the resulting graph does not contain any $F\in \mathcal{F}$ as a…

Data Structures and Algorithms · Computer Science 2021-02-12 Ajinkya Gaikwad , Soumen Maity

We show that every $r$-uniform hypergraph on $n$ vertices which does not contain a tight cycle has at most $O(n^{r-1} (\log n)^5)$ edges. This is an improvement on the previously best-known bound, of $n^{r-1} e^{O(\sqrt{\log n})}$, due to…

Combinatorics · Mathematics 2022-02-18 Shoham Letzter

One of the fundamental results in graph minor theory is that for every planar graph $H$, there is a minimum integer $f(H)$ such that graphs with no minor isomorphic to $H$ have treewidth at most $f(H)$. A lower bound for ${f(H)}$ can be…

Combinatorics · Mathematics 2026-01-16 J. Pascal Gollin , Kevin Hendrey , Sang-il Oum , Bruce Reed

In their famous 1974 paper introducing the local lemma, Erd\H{o}s and Lov\'asz posed a question-later referred by Erd\H{o}s as one of his three favorite open problems: What is the minimum number of edges in an $r$-uniform, intersecting…

Combinatorics · Mathematics 2025-04-15 Matija Bucić , Vanshika Jain , Varun Sivashankar

In 1975, Bollob\'{a}s, Erd\H{o}s, and Szemer\'{e}di asked for the smallest $\tau$ such that an $n \times n \times n$ tripartite graph with minimum degree $n + \tau$ must contain $K_{t, t, t}$, conjecturing that $\tau = \mathcal{O}(n^{1/2})$…

Combinatorics · Mathematics 2024-12-05 Francesco Di Braccio , Freddie Illingworth

The transversal hypergraph problem is the task of enumerating the minimal hitting sets of a hypergraph. It is a long-standing open question whether this can be done in output-polynomial time. For hypergraphs whose solutions have bounded…

Data Structures and Algorithms · Computer Science 2021-10-25 Thomas Bläsius , Tobias Friedrich , Julius Lischeid , Kitty Meeks , Martin Schirneck

Graph sparsification has been studied extensively over the past two decades, culminating in spectral sparsifiers of optimal size (up to constant factors). Spectral hypergraph sparsification is a natural analogue of this problem, for which…

Data Structures and Algorithms · Computer Science 2021-06-07 Michael Kapralov , Robert Krauthgamer , Jakab Tardos , Yuichi Yoshida

A hypergraph $(V,E)$ is called an interval hypergraph if there exists a linear order $l$ on $V$ such that every edge $e\in E$ is an interval w.r.t. $l$; we also assume that $\{j\}\in E$ for every $j\in V$. Our main result is a de…

Probability · Mathematics 2018-02-27 Julian Gerstenberg

An ordered hypergraph is a hypergraph $H$ with a specified linear ordering of the vertices, and the appearance of an ordered hypergraph $G$ in $H$ must respect the specified order on $V(G)$. In on-line Ramsey theory, Builder iteratively…

Combinatorics · Mathematics 2018-07-16 Xavier Perez-Gimenez , Pawel Pralat , Douglas B. West

Given a graph $H$, we say that a graph $G$ is $H$-saturated if $G$ contains no copy of $H$ but adding any new edge to $G$ creates a copy of $H$. Let $sat(n,K_r,t)$ be the minimum number of edges in a $K_r$-saturated graph on $n$ vertices…

Combinatorics · Mathematics 2023-02-28 Asier Calbet

Consider the hypergraph whose vertex set is a family of $n$ lines in general position in the plane, and whose hyperedges are induced by intersections with a family of pseudo-discs. We prove that the number of $t$-hyperedges is bounded by…

Combinatorics · Mathematics 2022-08-29 Chaya Keller , Balázs Keszegh , Dömötör Pálvölgyi

We improve the best known upper bound on the number of edges in a unit-distance graph on $n$ vertices for each $n\in\{16,\ldots,30\}$. When $n\leq 21$, our bounds match the best known lower bounds, and we fully enumerate the densest…

Combinatorics · Mathematics 2025-02-14 Boris Alexeev , Dustin G. Mixon , Hans Parshall

Let $F$ be a graph. We say that a hypergraph $H$ is a {\it Berge}-$F$ if there is a bijection $f : E(F) \rightarrow E(H )$ such that $e \subseteq f(e)$ for every $e \in E(F)$. Note that Berge-$F$ actually denotes a class of hypergraphs. The…

Combinatorics · Mathematics 2017-06-15 Cory Palmer , Michael Tait , Craig Timmons , Adam Zsolt Wagner

In this paper, we consider the problem of finding weak independent sets in a distributed network represented by a hypergraph. In this setting, each edge contains a set of r vertices rather than simply a pair, as in a standard graph. A…

Distributed, Parallel, and Cluster Computing · Computer Science 2024-11-21 Duncan Adamson , Will Rosenbaum , Paul G. Spirakis

We prove three main results about semialgebraic hypergraphs. First, we prove an optimal and oblivious regularity lemma. Fox, Pach, and Suk proved that the class of $k$-uniform semialgebraic hypergraphs satisfies a very strong regularity…

Combinatorics · Mathematics 2024-11-05 Jonathan Tidor , Hung-Hsun Hans Yu

We prove that the number of multigraphs with vertex set $\{1, \ldots, n\}$ such that every four vertices span at most nine edges is $a^{n^2 + o(n^2)}$ where $a$ is transcendental (assuming Schanuel's conjecture from number theory). This is…

Combinatorics · Mathematics 2019-03-27 Dhruv Mubayi , Caroline Terry

An oriented k-uniform hypergraph (a family of ordered k-sets) has the ordering property (or Property O) if for every linear order of the vertex set, there is some edge oriented consistently with the linear order. We find bounds on the…

Combinatorics · Mathematics 2016-08-24 Dwight Duffus , Bill Kay , Vojtech Rodl