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Given a family $\mathcal{H}$ of graphs, a graph $G$ is called $\mathcal{H}$-universal if $G$ contains every graph of $\mathcal{H}$ as a subgraph. Following the extensive research on universal graphs of small size for bounded-degree graphs,…

Combinatorics · Mathematics 2023-09-12 Peter Allen , Julia Böttcher , Anita Liebenau

A graph $G$ is $\textit{universal}$ for a (finite) family $\mathcal{H}$ of graphs if every $H \in \mathcal{H}$ is a subgraph of $G$. For a given family $\mathcal{H}$, the goal is to determine the smallest number of edges an…

Combinatorics · Mathematics 2024-01-12 Noga Alon , Natalie Dodson , Carmen Jackson , Rose McCarty , Rajko Nenadov , Lani Southern

We give a series of new lower bounds on the minimum number of vertices required by a graph to contain every graph of a given family as induced subgraph. In particular, we show that this induced-universal graph for $n$-vertex planar graphs…

Combinatorics · Mathematics 2025-08-18 Cyril Gavoille , Amaury Jacques

We characterise the slices of the category of graphs that are algebraically universal in terms of the structure of the slicing graph. In particular, we show that algebraic universality is obtained if, and only if, the slicing graph contains…

Combinatorics · Mathematics 2023-10-06 Ioannis Eleftheriadis

A graph $U$ is an induced universal graph for a family $F$ of graphs if every graph in $F$ is a vertex-induced subgraph of $U$. For the family of all undirected graphs on $n$ vertices Alstrup, Kaplan, Thorup, and Zwick [STOC 2015] give an…

Data Structures and Algorithms · Computer Science 2016-07-25 Mikkel Abrahamsen , Stephen Alstrup , Jacob Holm , Mathias Bæk Tejs Knudsen , Morten Stöckel

An old open problem in graph drawing asks for the size of a universal point set, a set of points that can be used as vertices for straight-line drawings of all n-vertex planar graphs. We connect this problem to the theory of permutation…

Computational Geometry · Computer Science 2015-07-16 Michael J. Bannister , Zhanpeng Cheng , William E. Devanny , David Eppstein

A graph $G$ is called universal for a family of graphs $\mathcal{F}$ if it contains every element $F \in \mathcal{F}$ as a subgraph. Let $\mathcal{F}(n,2)$ be the family of all graphs with maximum degree $2$. Ferber, Kronenberg, and Luh…

Combinatorics · Mathematics 2019-02-19 Olaf Parczyk

A finite set $P$ of points in the plane is $n$-universal with respect to a class $\mathcal{C}$ of planar graphs if every $n$-vertex graph in $\mathcal{C}$ admits a crossing-free straight-line drawing with vertices at points of $P$. For the…

Computational Geometry · Computer Science 2023-03-02 Stefan Felsner , Hendrik Schrezenmaier , Felix Schröder , Raphael Steiner

A hypergraph $H$ is called universal for a family $\mathcal{F}$ of hypergraphs, if it contains every hypergraph $F \in \mathcal{F}$ as a copy. For the family of $r$-uniform hypergraphs with maximum vertex degree bounded by $\Delta$ and at…

Combinatorics · Mathematics 2016-05-16 Samuel Hetterich , Olaf Parczyk , Yury Person

A set P of points in R^2 is n-universal, if every planar graph on n vertices admits a plane straight-line embedding on P. Answering a question by Kobourov, we show that there is no n-universal point set of size n, for any n>=15. Conversely,…

Computational Geometry · Computer Science 2013-08-28 Jean Cardinal , Michael Hoffmann , Vincent Kusters

The Tur\'an number $\text{ex}(n,H)$ of a graph $H$ is the maximal number of edges in an $H$-free graph on $n$ vertices. In $1983$ Chung and Erd\H{o}s asked which graphs $H$ with $e$ edges minimize $\text{ex}(n,H)$. They resolved this…

Combinatorics · Mathematics 2023-06-22 Matija Bucić , Nemanja Draganić , Benny Sudakov

A homogeneous set of an $n$-vertex graph is a set $X$ of vertices ($2\le |X|\le n-1$) such that every vertex not in $X$ is either complete or anticomplete to $X$. A graph is called prime if it has no homogeneous set. A chain of length $t$…

Combinatorics · Mathematics 2016-07-26 Maria Chudnovsky , Ringi Kim , Sang-il Oum , Paul Seymour

We introduce and study the problem of constructing geometric graphs that have few vertices and edges and that are universal for planar graphs or for some sub-class of planar graphs; a geometric graph is \emph{universal} for a class…

Combinatorics · Mathematics 2020-06-22 Fabrizio Frati , Michael Hoffmann , Csaba D. Tóth

In the present paper, we introduce the concept of universal graph series. We then present four invariants of graphs and discuss some of their properties. In particular, one of these invariants is a generalization of the chromatic symmetric…

Combinatorics · Mathematics 2025-01-22 Tsuyoshi Miezaki , Akihiro Munemasa , Yusaku Nishimura , Tadashi Sakuma , Shuhei Tsujie

For a family $\mathcal{F}$ of graphs, a graph $G$ is called \emph{$\mathcal{F}$-universal} if $G$ contains every graph in $\mathcal{F}$ as a subgraph. Let $\mathcal{F}_n(d)$ be the family of all graphs on $n$ vertices with maximum degree at…

Combinatorics · Mathematics 2015-03-17 Jeong Han Kim , Sang June Lee

A connected digraph in which the in-degree of any vertex equals its out-degree is Eulerian; this baseline result is used as the basis of existence proofs for universal cycles (also known as ucycles or generalized deBruijn cycles or…

Combinatorics · Mathematics 2019-11-22 Amelia Cantwell , Juliann Geraci , Anant Godbole , Cristobal Padilla

Given a class of graphs F, we say that a graph G is universal for F, or F-universal, if every H in F is contained in G as a subgraph. The construction of sparse universal graphs for various families F has received a considerable amount of…

Combinatorics · Mathematics 2011-08-24 Daniel Johannsen , Michael Krivelevich , Wojciech Samotij

A graph is unipolar if it can be partitioned into a clique and a disjoint union of cliques, and a graph is a generalised split graph if it or its complement is unipolar. A unipolar partition of a graph can be used to find efficiently the…

Data Structures and Algorithms · Computer Science 2016-04-05 Colin McDiarmid , Nikola Yolov

A universal cycle (u-cycle) for permutations of length $n$ is a cyclic word, any size $n$ window of which is order-isomorphic to exactly one permutation of length $n$, and all permutations of length $n$ are covered. It is known that…

Combinatorics · Mathematics 2024-08-13 Sergey Kitaev , Dun Qiu

A graph $G$ is universal for a class of graphs $\mathcal{C}$, if, up to isomorphism, $G$ contains every graph in $\mathcal{C}$ as a subgraph. In 1978, Chung and Graham asked for the minimal number $s(n)$ of edges in a graph with $n$…

Combinatorics · Mathematics 2026-03-27 Julian Becker , Konstantinos Panagiotou , Matija Pasch
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