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Graph neural networks (GNNs) are a powerful architecture for tackling graph learning tasks, yet have been shown to be oblivious to eminent substructures such as cycles. We present TOGL, a novel layer that incorporates global topological…

机器学习 · 计算机科学 2022-03-18 Max Horn , Edward De Brouwer , Michael Moor , Yves Moreau , Bastian Rieck , Karsten Borgwardt

A monotone cylindrical graph is a topological graph drawn on an open cylinder with an infinite vertical axis satisfying the condition that every vertical line intersects every edge at most once. It is called simple if any pair of its edges…

组合数学 · 数学 2014-12-15 Andres J. Ruiz-Vargas

A nut graph is a simple graph of order 2 or more for which the adjacency matrix has a single zero eigenvalue such that all non-zero kernel eigenvectors have no zero entry (i.e. are full). It is shown by construction that every finite group…

组合数学 · 数学 2024-05-08 Nino Bašić , Patrick W. Fowler

Given $t\geq 2$ and $0\leq k\leq t$, we prove that the number of labelled $k$-connected chordal graphs with $n$ vertices and tree-width at most $t$ is asymptotically $c n^{-5/2} \gamma^n n!$, as $n\to\infty$, for some constants $c,\gamma…

组合数学 · 数学 2024-02-02 Jordi Castellví , Michael Drmota , Marc Noy , Clément Requilé

Topological drawings are representations of graphs in the plane, where vertices are represented by points, and edges by simple curves connecting the points. A drawing is simple if two edges intersect at most in a single point, either at a…

计算几何 · 计算机科学 2022-09-08 Alfredo García , Alexander Pilz , Javier Tejel

A nut graph is a simple graph for which the adjacency matrix has a single zero eigenvalue such that all non-zero kernel eigenvectors have no zero entry. If the isolated vertex is excluded as trivial, nut graphs have seven or more vertices;…

组合数学 · 数学 2023-12-07 Nino Bašić , Patrick W. Fowler , Tomaž Pisanski

Let $C_{s,t}$ be the complete bipartite geometric graph, with $s$ and $t$ vertices on two distinct parallel lines respectively, and all $s t$ straight-line edges drawn between them. In this paper, we show that every complete bipartite…

组合数学 · 数学 2026-02-25 Balázs Keszegh , Andrew Suk , Gábor Tardos , Ji Zeng

Graph pebbling is a network optimization model for transporting discrete resources that are consumed in transit: the movement of two pebbles across an edge consumes one of the pebbles. The pebbling number of a graph is the fewest number of…

组合数学 · 数学 2012-11-20 Liliana Alcón , Marisa Gutierrez , Glenn Hurlbert

Suppose that $T_n$ is a Toeplitz matrix whose entries come from a sequence of independent but not necessarily identically distributed random variables with mean zero. Under some additional tail conditions, we show that the spectral norm of…

概率论 · 数学 2007-10-29 Mark W. Meckes

A partition $\Sigma = \{S_1, S_2, \dots, S_k\}$ of the vertex set $V(G)$ is a resolving partition if every pair of distinct vertices in $G$ has a unique representation relative to $\Sigma$. The partition dimension, $pd(G)$, is the minimum…

组合数学 · 数学 2026-05-13 Ali Zafari , Saeid Alikhani

Threshold graphs are graphs that can be characterized in a number of different ways. For example, they are graphs that are $P_4,\ C_4,\ 2K_2$--free. They may also be characterized by a finite sequence of positive integers $a_1, \ldots,…

组合数学 · 数学 2026-05-07 James L. Borg , Irene Sciriha , Zoia Sherman

Let $X$ be a finite, simple graph with vertex set $V(X)$. The $2$-distance graph $T_2(X)$ of $X$ is the graph with the same vertex set as $X$ and two vertices are adjacent if and only if their distance in $X$ is exactly $2$. A graph $G$ is…

组合数学 · 数学 2015-10-06 Ramuel P. Ching , I. J. L. Garces

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…

组合数学 · 数学 2018-03-20 János Pach , Bruce Reed , Yelena Yuditsky

A topological drawing of a graph is fan-planar if for each edge $e$ the edges crossing $e$ form a star and no endpoint of $e$ is enclosed by $e$ and its crossing edges. A fan-planar graph is a graph admitting such a drawing. Equivalently,…

离散数学 · 计算机科学 2021-07-16 Michael Kaufmann , Torsten Ueckerdt

The transmission of a vertex $v$ of a graph $G$ is the sum of distances from $v$ to all the other vertices in $G$. A graph is transmission irregular if all of its vertices have pairwise different transmissions. A starlike tree…

组合数学 · 数学 2020-04-20 Kexiang Xu , Sandi Klavžar

We investigate straight-line drawings of topological graphs that consist of a planar graph plus one edge, also called almost-planar graphs. We present a characterization of such graphs that admit a straight-line drawing. The…

计算几何 · 计算机科学 2015-07-01 Peter Eades , Seok-Hee Hong , Giuseppe Liotta , Naoki Katoh , Sheung-Hung Poon

Let $G=(V,E)$ be a graph of order $n$ and let $1\leq k< n$ be an integer. The $k$-token graph of $G$ is the graph whose vertices are all the $k$-subsets of $V$, two of which are adjacent whenever their symmetric difference is a pair of…

组合数学 · 数学 2018-02-21 Walter Carballosa , Ruy Fabila-Monroy , Jesús Leaños , Luis Manuel Rivera

A graph is \emph{fan-crossing free} if it has a drawing in the plane so that each edge is crossed by independent edges, that is the crossing edges have distinct vertices. On the other hand, it is \emph{fan-crossing} if the crossing edges…

离散数学 · 计算机科学 2020-12-14 Franz J. Brandenburg

The independent domination number $i(G)$ of a graph $G$ is the minimum cardinality of a maximal independent set of $G$, also called an $i(G)$-set. The $i$-graph of $G$ is the graph whose vertices correspond to the $i(G)$-sets, and where two…

组合数学 · 数学 2023-05-30 Richard Brewster , Kieka Mynhardt , Laura Teshima

We construct a hereditary class of triangle-free graphs with unbounded chromatic number, in which every non-trivial graph either contains a pair of non-adjacent twins or has an edgeless vertex cutset of size at most two. This answers in the…