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We introduce two topological non-$\Sigma$ operad structures on planar line arrangements subject to a certain geometric order condition, ensuring a well-defined notion of particle ordering on a distinguished line. This is interpreted in…

Mathematical Physics · Physics 2024-12-19 Denis Bashkirov

A linear layout of a graph $ G $ consists of a linear order $\prec$ of the vertices and a partition of the edges. A part is called a queue (stack) if no two edges nest (cross), that is, two edges $ (v,w) $ and $ (x,y) $ with $ v \prec x…

Combinatorics · Mathematics 2023-05-26 Henry Förster , Michael Kaufmann , Laura Merker , Sergey Pupyrev , Chrysanthi Raftopoulou

In this paper we study the computational complexity of the Upward Planarity Extension problem, which takes in input an upward planar drawing $\Gamma_H$ of a subgraph $H$ of a directed graph $G$ and asks whether $\Gamma_H$ can be extended to…

Data Structures and Algorithms · Computer Science 2019-02-19 Giordano Da Lozzo , Giuseppe Di Battista , Fabrizio Frati

An outer-1-planar graph is a graph admitting a drawing in the plane so that all vertices appear in the outer region of the drawing and every edge crosses at most one other edge. This paper establishes the local structure of outer-1-planar…

Combinatorics · Mathematics 2023-06-22 Yan Li , Xin Zhang

Network-based modeling of complex systems and data using the language of graphs has become an essential topic across a range of different disciplines. Arguably, this graph-based perspective derives its success from the relative simplicity…

Social and Information Networks · Computer Science 2023-08-11 Christian Bick , Elizabeth Gross , Heather A. Harrington , Michael T. Schaub

We prove that the ordered configuration spaces of planar graphs have the highest possible topological complexity generically, as predicted by a conjecture of Farber. Our argument establishes the same generic maximality for all higher…

Algebraic Topology · Mathematics 2021-08-03 Ben Knudsen

The slope number of a graph $G$ is the smallest number of slopes needed for the segments representing the edges in any straight-line drawing of $G$. It serves as a measure of the visual complexity of a graph drawing. Several bounds on the…

Computational Geometry · Computer Science 2022-10-13 Jonathan Klawitter , Johannes Zink

We introduce and study the {\em orderly spanning trees} of plane graphs. This algorithmic tool generalizes {\em canonical orderings}, which exist only for triconnected plane graphs. Although not every plane graph admits an orderly spanning…

Data Structures and Algorithms · Computer Science 2015-02-06 Yi-Ting Chiang , Ching-Chi Lin , Hsueh-I Lu

In an upward planar 2-slope drawing of a digraph, edges are drawn as straight-line segments in the upward direction without crossings using only two different slopes. We investigate whether a given upward planar digraph admits such a…

Discrete Mathematics · Computer Science 2022-07-06 Jonathan Klawitter , Tamara Mchedlidze

A graph generative model defines a distribution over graphs. One type of generative model is constructed by autoregressive neural networks, which sequentially add nodes and edges to generate a graph. However, the likelihood of a graph under…

Machine Learning · Statistics 2021-06-15 Xiaohui Chen , Xu Han , Jiajing Hu , Francisco J. R. Ruiz , Liping Liu

This paper considers 1-string representations of planar graphs that are order-preserving in the sense that the order of crossings along the curve representing vertex $v$ is the same as the order of edges in the clockwise order around $v$ in…

Computational Geometry · Computer Science 2016-09-27 Therese Biedl , Martin Derka

The page number of a directed acyclic graph $G$ is the minimum $k$ for which there is a topological ordering of $G$ and a $k$-coloring of the edges such that no two edges of the same color cross, i.e., have alternating endpoints along the…

Combinatorics · Mathematics 2023-05-10 Paul Jungeblut , Laura Merker , Torsten Ueckerdt

A graph is 1-planar if it can be drawn on a plane so that each edge is crossed by at most one other edge. In this paper, we first give a useful structural theorem for 1-planar graphs, and then apply it to the list edge and list total…

Combinatorics · Mathematics 2019-12-17 Xin Zhang , Bei Niu , Jiguo Yu

We write down a series of basic laws for (strict) higher-order circuit diagrams. More precisely, we define higher-order circuit theories in terms of: (a) nesting, (b) temporal and spatial composition, and (c) equivalence between lower-order…

Quantum Physics · Physics 2026-02-24 Matt Wilson

Constructions of directed configuration graphs based on a given bi-degree distribution were introduced in random graph theory some years ago. These constructions lead to graphs where the degrees of two nodes belonging to the same edge are…

Probability · Mathematics 2017-01-13 Philippe Deprez , Mario V. Wüthrich

This paper considers a hyperplane arrangement constructed with a subset of a set of all simple paths in a graph. A connection of the constructed arrangement to the maximum matching problem is established. Moreover, the problem of finding…

Combinatorics · Mathematics 2022-05-31 Aleksey Bolotnikov

Many "good" topologies for interconnection networks are based on line digraphs of regular digraphs. These digraphs support unitary matrices. We propose the property "being the digraph of a unitary matrix" as additional criterion for the…

Discrete Mathematics · Computer Science 2007-05-23 Simone Severini

A queue layout of a graph G consists of a linear order of the vertices of G and a partition of the edges of G into queues, so that no two independent edges of the same queue are nested. The queue number of G is the minimum number of queues…

Data Structures and Algorithms · Computer Science 2018-09-10 Jawaherul Md. Alam , Michael A. Bekos , Martin Gronemann , Michael Kaufmann , Sergey Pupyrev

Random directed acyclic graphs (DAGs) based on imposing an order on Erd\H{o}s-R\'enyi and scale free random graphs are widely used for evaluating causal discovery algorithms. We show that in such DAGs, the set of nodes reachable via open…

Methodology · Statistics 2026-05-08 Alexander G. Reisach , Antoine Chambaz , Gilles Blanchard , Sebastian Weichwald

Arrangement theory plays an essential role in the study of the unfolding model used in many fields. This paper describes how arrangement theory can be usefully employed in solving the problems of counting (i) the number of admissible…

Combinatorics · Mathematics 2013-01-11 Hidehiko Kamiya , Akimichi Takemura , Norihide Tokushige