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We prove that graphs excluding a fixed immersion have bounded nonrepetitive chromatic number. More generally, we prove that if $H$ is a fixed planar graph that has a planar embedding with all the vertices with degree at least 4 on a single…

Combinatorics · Mathematics 2019-07-15 Paul Wollan , David R. Wood

A homogeneous set of a graph $G$ is a set $X$ of vertices such that $2\le \lvert X\rvert <\lvert V(G)\rvert$ and no vertex in $V(G)-X$ has both a neighbor and a non-neighbor in $X$. A graph is prime if it has no homogeneous set. We present…

Discrete Mathematics · Computer Science 2019-01-16 Robert Brignall , Hojin Choi , Jisu Jeong , Sang-il Oum

Computing the embedding distribution of a given graph is a fundamental question in topological graph theory. In this article, we extend our viewpoint to a sequence of graphs and consider their asymptotic embedding distributions, which are…

Combinatorics · Mathematics 2025-07-22 Yichao Chen , Wenjie Fang , Zhicheng Gao , Jinlian Zhang

We construct exponential objects in categories of generalized uniform hypergraphs and use embeddings induced by nerve-realization adjunctions to show why conventional categories of graphs and hypergraphs do not have exponential objects.

Combinatorics · Mathematics 2018-07-26 Martin Schmidt

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

In contrast to the usual quantum systems which have at most a finite number of open spectral gaps if they are periodic in more than one direction, periodic quantum graphs may have gaps arbitrarily high in the spectrum. This property of…

Quantum Physics · Physics 2020-05-26 Pavel Exner , Ondřej Turek

We collect some general results on graph limits associated to hereditary classes of graphs. As examples, we consider some classes defined by forbidden subgraphs and some classes of intersection graphs, including triangle-free graphs,…

Combinatorics · Mathematics 2013-03-29 Svante Janson

When can a unimodular random planar graph be drawn in the Euclidean or the hyperbolic plane in a way that the distribution of the random drawing is isometry-invariant? This question was answered for one-ended unimodular graphs in…

Probability · Mathematics 2026-03-24 Ádám Timár , László Márton Tóth

We prove that no separable Banach algebra is universal for homomorphic embeddings of all separable Banach algebras, whether embeddings are merely bounded or required to be contractive. The same holds in the commutative category. The proof…

Functional Analysis · Mathematics 2025-11-12 Tomasz Kania

We study 3-random-like graphs, that is, sequences of graphs in which the densities of triangles and anti-triangles converge to 1/8. Since the random graph ${\mathcal G}_{n,1/2}$ is, in particular, 3-random-like, this can be viewed as a weak…

Combinatorics · Mathematics 2019-02-20 Dan Hefetz , Mykhaylo Tyomkyn

We consider first order expressible properties of random perfect graphs. That is, we pick a graph $G_n$ uniformly at random from all (labelled) perfect graphs on $n$ vertices and consider the probability that it satisfies some graph…

Combinatorics · Mathematics 2018-10-02 Tobias Müller , Marc Noy

A "folklore conjecture, probably due to Tutte" (as described in [P.D. Seymour, Sums of circuits, Graph theory and related topics (Proc. Conf., Univ. Waterloo, 1977), pp. 341-355, Academic Press, 1979]) asserts that every bridgeless cubic…

Combinatorics · Mathematics 2011-01-14 Bojan Mohar

A graph is maximal knotless if it is edge maximal for the property of knotless embedding in $R^3$. We show that such a graph has at least $\frac74 |V|$ edges, and construct an infinite family of maximal knotless graphs with $|E| <…

Geometric Topology · Mathematics 2023-06-21 Lindsay Eakins , Thomas Fleming , Thomas W. Mattman

We show that there are $O(n \cdot 4^{n/11})$ planar graphs on $n$ vertices which do not admit a simultaneous straight-line embedding on any $n$-point set in the plane. In particular, this improves the best known bound $O(n!)$ significantly.

Combinatorics · Mathematics 2023-10-26 Ritesh Goenka , Pardis Semnani , Chi Hoi Yip

Graph encoder embedding, a recent technique for graph data, offers speed and scalability in producing vertex-level representations from binary graphs. In this paper, we extend the applicability of this method to a general graph model, which…

Machine Learning · Statistics 2024-10-24 Cencheng Shen

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

We study classes of countable graphs where every member does not contain a given finite graph as an induced subgraph -- denoted by $\mathsf{Free}(\mathcal{G})$ for a given finite graph $\mathcal{G}$. Our main results establish a structural…

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

We introduce and study embeddings of graphs in finite projective planes, and present related results for some families of graphs including complete graphs and complete bipartite graphs. We also make connections between embeddings of graphs…

Combinatorics · Mathematics 2013-10-02 Keith Mellinger , Ryan Vaughn , Oscar Vega

The shift-enabled property of an underlying graph is essential in designing distributed filters. This article discusses when a random graph is shift-enabled. In particular, popular graph models ER, WS, BA random graph are used, weighted and…

Discrete Mathematics · Computer Science 2021-09-02 Liyan Chen , Samuel Cheng , Vladimir Stankovic , Lina Stankovic
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