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We consider random graphs sampled uniformly from a structured class of graphs, such as the class of graphs embeddable in a given surface. We sharpen and extend earlier results on pendant appearances, concerning for example numbers of…

Combinatorics · Mathematics 2024-05-07 Colin McDiarmid

In this paper, we present a hybrid graph-drawing algorithm (GDA) for layouting large, naturally-clustered, disconnected graphs. We called it a hybrid algorithm because it is an implementation of a series of already known graph-drawing and…

Graphics · Computer Science 2015-07-13 Toni-Jan Keith P. Monserrat , Jaderick P. Pabico , Eliezer A. Albacea

Unigraphs are graphs identifiable up to isomorphism from their degree sequences. Given a class $\mathcal{A}$ of graphs, we define the class of $\mathcal{A}$-unigraphs to be graphs identifiable from degree sequence and membership in…

Combinatorics · Mathematics 2024-06-07 R. Whitman

In previous work, the author defined the intersection graph of a chord diagram associated with string links (as in the theory of finite type invariants). In this paper, we classify the trees which can be obtained as intersection graphs of…

Geometric Topology · Mathematics 2007-05-23 Blake Mellor

A generalized vertex join of a graph is obtained by joining an arbitrary multiset of its vertices to a new vertex. We present a low-order polynomial time algorithm for finding the chromatic polynomials of generalized vertex joins of trees,…

Discrete Mathematics · Computer Science 2015-01-20 Boris Brimkov , Illya V. Hicks

Graphs can be associated with a matrix according to some rule and we can find the spectrum of a graph with respect to that matrix. Two graphs are cospectral if they have the same spectrum. Constructions of cospectral graphs help us…

Combinatorics · Mathematics 2020-06-02 Kate Lorenzen

Much information about a graph can be obtained by studying its spanning trees. On the other hand, a graph can be regarded as a 1-dimensional cell complex, raising the question of developing a theory of trees in higher dimension. As observed…

Combinatorics · Mathematics 2015-06-24 Art M. Duval , Caroline J. Klivans , Jeremy L. Martin

We unify several seemingly different graph and digraph classes under one umbrella. These classes are all broadly speaking different generalizations of interval graphs, and include, in addition to interval graphs, also adjusted interval…

Discrete Mathematics · Computer Science 2018-06-28 Pavol Hell , Jing Huang , Ross M. McConnell , Arash Rafiey

We give characterizations of the structure and degree sequences of hereditary unigraphs, those graphs for which every induced subgraph is the unique realization of its degree sequence. The class of hereditary unigraphs properly contains the…

Combinatorics · Mathematics 2015-08-04 Michael D. Barrus

The paper discusses quantum graphs with a vertex coupling which interpolates between the common one of the $\delta$ type and a coupling introduced recently by two of the authors which exhibits a preferred orientation. Describing the…

Mathematical Physics · Physics 2018-06-11 Pavel Exner , Ondřej Turek , Miloš Tater

In this paper, we revisit the split decomposition of graphs and give new combinatorial and algorithmic results for the class of totally decomposable graphs, also known as the distance hereditary graphs, and for two non-trivial subclasses,…

Discrete Mathematics · Computer Science 2011-04-19 Emeric Gioan , Christophe Paul

Recently, so-called treebased phylogenetic networks have gained considerable interest in the literature, where a treebased network is a network that can be constructed from a phylogenetic tree, called the base tree, by adding additional…

Populations and Evolution · Quantitative Biology 2019-11-28 Mareike Fischer , Michelle Galla , Lina Herbst , Yangjing Long , Kristina Wicke

A path graph is the intersection graph of paths in a tree. A directed path graph is the intersection graph of paths in a directed tree. Even if path graphs and directed path graphs are characterized very similarly, their recognition…

Data Structures and Algorithms · Computer Science 2025-05-07 Lorenzo Balzotti

A theory of orientation on gain graphs (voltage graphs) is developed to generalize the notion of orientation on graphs and signed graphs. Using this orientation scheme, the line graph of a gain graph is studied. For a particular family of…

Combinatorics · Mathematics 2015-06-17 Nathan Reff

In this paper we introduce the horizon visibility graph, a simple extension to the popular horizontal visibility graph representation of a time series, and show that it possesses a rigorous mathematical foundation in computational algebraic…

Data Analysis, Statistics and Probability · Physics 2019-06-24 Colin Stephen

We consider the graph class Grounded-L corresponding to graphs that admit an intersection representation by L-shaped curves, where additionally the topmost points of each curve are assumed to belong to a common horizontal line. We prove…

Combinatorics · Mathematics 2019-11-06 Vít Jelínek , Martin Töpfer

A connected and nonempty graph A is defined as generalized t-edge distance-balanced, while for each edge f={\alpha}\{beta} the number of edges nearer to {\alpha} than \{beta} are equal to t-times of edges nearer to \{beta} than to {\alpha},…

Combinatorics · Mathematics 2023-12-25 Zohreh Aliannejadi , Mehdi Alaeiyan , Alireza Gilani

The vertices of a $k$-token graph of a graph $G$ correspond to $k$ indistinguishable tokens placed on $k$ different vertices of $G$. Changing some conditions on both the nature of the tokens and the number of tokens allowed in each vertex…

Combinatorics · Mathematics 2026-04-07 Xiaodi Song , Cristina Dalfó , Miquel Àngel Fiol , Mercè Mora , Shenggui Zhang

Chain graphs combine directed and undirected graphs and their underlying mathematics combines properties of the two. This paper gives a simplified definition of chain graphs based on a hierarchical combination of Bayesian (directed) and…

Artificial Intelligence · Computer Science 2013-02-21 Wray L. Buntine

Geometric graphs appear in many real-world data sets, such as road networks, sensor networks, and molecules. We investigate the notion of distance between embedded graphs and present a metric to measure the distance between two geometric…

Data Structures and Algorithms · Computer Science 2024-07-15 Erin Wolf Chambers , Elizabeth Munch , Sarah Percival , Xinyi Wang