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We introduce a method to embed edge-colored graphs into families of expander graphs, which generalizes a framework developed by Dragani\'c, Krivelevich, and Nenadov (2022). As an application, we show that each family of sufficiently…

Combinatorics · Mathematics 2025-01-27 Ben Lund , Chuandong Xu

The primary objective of this paper is to investigate the notions of geometric and sequential convexity within a graph-theoretic framework, with the aim of examining various structural properties and exploring the connection between these…

General Mathematics · Mathematics 2026-04-24 Angshuman R. Goswami

A random geometric digraph $G_n$ is constructed by taking $\{X_1,X_2,... X_n\}$ in $\mathbb{R}^2$ independently at random with a common bounded density function. Each vertex $X_i$ is assigned at random a sector $S_i$ of central angle…

Combinatorics · Mathematics 2019-09-18 Yilun Shang

The ring of graph invariants is spanned by the basic graph invariants which calculate the number of subgraphs isomorphic to a given graph in other graphs. These subgraphs counting invariants are not algebraically independent. In our view…

Combinatorics · Mathematics 2008-12-11 Tomi Mikkonen

The design spectrum of a simple graph $G$ is the set of positive integers $n$ such that there exists an edgewise decomposition of the complete graph $K_n$ into $n(n - 1)/(2 |E(G)|)$ copies of $G$. We compute the design spectra for 7788…

Combinatorics · Mathematics 2024-01-08 Anthony D. Forbes , Carrie G. Rutherford

Let $D$ be a connected oriented graph. A set $S \subseteq V(D)$ is convex in $D$ if, for every pair of vertices $x, y \in S$, the vertex set of every $xy$-geodesic, ($xy$ shortest directed path) and every $yx$-geodesic in $D$ is contained…

Le n be any positive integer. A hyperbinary expansion of n is are presentation of n as sum of powers of 2, each power being used at most twice. In this paper we study some properties of a suitable edge-coloured and vertex-weighted oriented…

Combinatorics · Mathematics 2016-10-05 M. Brunetti , A. D'Aniello

A pedigree is a directed graph in which each vertex (except the founder vertices) has two parents. The main result in this paper is a construction of an infinite family of counter examples to a reconstruction problem on pedigrees, thus…

Combinatorics · Mathematics 2010-09-21 Bhalchandra D. Thatte

For a given permutation or set partition there is a natural way to assign a genus. Counting all permutations or partitions of a fixed genus according to cycle lengths or block sizes, respectively, is the main content of this article. After…

Combinatorics · Mathematics 2025-01-03 Alexander Hock

Distance-hereditary graphs form an important class of graphs, from the theoretical point of view, due to the fact that they are the totally decomposable graphs for the split-decomposition. The previous best enumerative result for these…

Combinatorics · Mathematics 2016-08-05 Cédric Chauve , Éric Fusy , Jérémie Lumbroso

A monotone drawing of a planar graph $G$ is a planar straight-line drawing of $G$ where a monotone path exists between every pair of vertices of $G$ in some direction. Recently monotone drawings of planar graphs have been proposed as a new…

Computational Geometry · Computer Science 2013-10-24 Md. Iqbal Hossain , Md. Saidur Rahman

A class of countable infinite graphs with unbounded vertex degree is considered. In these graphs, the vertices of large degree `repel' each other, which means that the path distance between two such vertices cannot be smaller than a certain…

Combinatorics · Mathematics 2012-11-22 Dorota Kȩpa-Maksymowicz , Yuri Kozitsky

A rooted tree is balanced if the degree of a vertex depends only on its distance to the root. In this paper we determine the sharp threshold for the appearance of a large family of balanced spanning trees in the random geometric graph…

Combinatorics · Mathematics 2023-03-28 Alberto Espuny Díaz , Lyuben Lichev , Dieter Mitsche , Alexandra Wesolek

The sorting number of a graph with $n$ vertices is the minimum depth of a sorting network with $n$ inputs and outputs that uses only the edges of the graph to perform comparisons. Many known results on sorting networks can be stated in…

Data Structures and Algorithms · Computer Science 2022-03-22 Indranil Banerjee , Dana Richards , Igor Shinkar

We characterize the graphs with loops whose degree sequences have no repeated values and find their adjacency spectrum. In the case of simple graphs, such graphs are called anti-regular graphs and are examples of threshold graphs. The…

Combinatorics · Mathematics 2019-12-16 Cesar O. Aguilar

This article focuses on a class of properly edge-colored graphs, which arise from topological combinatorics, and investigates their embeddings onto surfaces. Specifically, these graphs are known as the dual graphs of balanced normal…

Geometric Topology · Mathematics 2025-12-03 Biplab Basak , Sourav Sarkar

A {\em string graph} is the intersection graph of a family of continuous arcs in the plane. The intersection graph of a family of plane convex sets is a string graph, but not all string graphs can be obtained in this way. We prove the…

Combinatorics · Mathematics 2018-03-20 János Pach , Bruce Reed , Yelena Yuditsky

The geometric thickness of a graph G is the minimum integer k such that there is a straight line drawing of G with its edge set partitioned into k plane subgraphs. Eppstein [Separating thickness from geometric thickness. In: Towards a…

Combinatorics · Mathematics 2007-05-23 Janos Barat , Jiri Matousek , David R. Wood

A graph is 2-degenerate if every subgraph contains a vertex of degree at most 2. We show that every 2-degenerate graph can be drawn with straight lines such that the drawing decomposes into 4 plane forests. Therefore, the geometric…

Combinatorics · Mathematics 2023-03-01 Rahul Jain , Marco Ricci , Jonathan Rollin , André Schulz

Let $A$ be a gentle algebra. For every collection of string and band diagrammes, we consider the constructible subset of the variety of representations containing all modules with this underlying diagramme. We study degenerations of such…

Representation Theory · Mathematics 2026-01-21 Judith Marquardt