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An \emph{obstacle representation} of a graph $G$ is a straight-line drawing of $G$ in the plane together with a collection of connected subsets of the plane, called \emph{obstacles}, that block all non-edges of $G$ while not blocking any of…

An \emph{outer-string representation} of a graph $G$ is an intersection representation of $G$ where vertices are represented by curves (strings) inside the unit disk and each curve has exactly one endpoint on the boundary of the unit disk…

Combinatorics · Mathematics 2026-05-18 Todor Antić , Vít Jelínek , Jan Kratochvíl , Peter Stumpf

The definition of $1$-planar graphs naturally extends graph planarity, namely a graph is $1$-planar if it can be drawn in the plane with at most one crossing per edge. Unfortunately, while testing graph planarity is solvable in linear time,…

Computational Geometry · Computer Science 2019-11-05 Carla Binucci , Walter Didimo , Fabrizio Montecchiani

For a graph $G=(V,E)$, a set $S \subseteq V$ is a $[1,2]$-set if it is a dominating set for $G$ and each vertex $v \in V \setminus S$ is dominated by at most two vertices of $S$, i.e. $1 \leq \vert N(v) \cap S \vert \leq 2$. Moreover a set…

Discrete Mathematics · Computer Science 2017-07-21 P. Sharifani , M. R. Hooshmandasl

A visibility representation is a classical drawing style of planar graphs. It displays the vertices of a graph as horizontal vertex-segments, and each edge is represented by a vertical edge-segment touching the segments of its end vertices;…

Computational Geometry · Computer Science 2013-08-26 Franz J. Brandenburg

An efficient implicit representation of an $n$-vertex graph $G$ in a family $\mathcal{F}$ of graphs assigns to each vertex of $G$ a binary code of length $O(\log n)$ so that the adjacency between every pair of vertices can be determined…

Combinatorics · Mathematics 2021-12-15 Hamed Hatami , Pooya Hatami

Pre-trained sequence-to-sequence language models have led to widespread success in many natural language generation tasks. However, there has been relatively less work on analyzing their ability to generate structured outputs such as…

Computation and Language · Computer Science 2022-04-12 Swarnadeep Saha , Prateek Yadav , Mohit Bansal

The graph of overlapping permutations is defined in a way analogous to the De Bruijn graph on strings of symbols. That is, for every permutation $\pi = \pi_{1} \pi_{2} ... \pi_{n+1}$ there is a directed edge from the standardization of…

Combinatorics · Mathematics 2014-10-08 Richard Ehrenborg , Sergey Kitaev , Einar Steingrimsson

Graph-based text representation focuses on how text documents are represented as graphs for exploiting dependency information between tokens and documents within a corpus. Despite the increasing interest in graph representation learning,…

Computation and Language · Computer Science 2022-10-13 Wenzhe Li , Nikolaos Aletras

A graph is said to be well-dominated if all its minimal dominating sets are of the same size. The class of well-dominated graphs forms a subclass of the well studied class of well-covered graphs. While the recognition problem for the class…

Discrete Mathematics · Computer Science 2023-06-22 Didem Gözüpek , Ademir Hujdurović , Martin Milanič

A graph H is common if the number of monochromatic copies of H in a 2-edge-coloring of the complete graph is asymptotically minimized by the random coloring. The classification of common graphs is one of the most intriguing problems in…

Combinatorics · Mathematics 2022-04-28 Robert Hancock , Daniel Kral , Matjaz Krnc , Jan Volec

We consider the class ${\cal A}$ of graphs that contain no odd hole, no antihole of length at least 5, and no "prism" (a graph consisting of two disjoint triangles with three disjoint paths between them) and the class ${\cal A}'$ of graphs…

Discrete Mathematics · Computer Science 2013-09-03 Frédéric Maffray , Nicolas Trotignon

A graph $G$ is {\it weakly semiregular} if there are two numbers $a,b$, such that the degree of every vertex is $a$ or $b$. The {\it weakly semiregular number} of a graph $G$, denoted by $wr(G)$, is the minimum number of subsets into which…

Combinatorics · Mathematics 2017-01-24 Arash Ahadi , Ali Dehghan , Mohsen Mollahajiaghaei

A graph $X$ is said to be a pattern polynomial graph if its adjacency algebra is a coherent algebra. In this study we will find a necessary and sufficient condition for a graph to be a pattern polynomial graph. Some of the properties of the…

Combinatorics · Mathematics 2011-06-24 A. Satyanarayana Reddy , Shashank K Mehta

In combinatorics on words, a word $w$ over an alphabet $\Sigma$ is said to avoid a pattern $p$ over an alphabet $\Delta$ of variables if there is no factor $f$ of $w$ such that $f=h(p)$ where $h:\Delta^*\to\Sigma^*$ is a non-erasing…

Discrete Mathematics · Computer Science 2016-10-14 Pascal Ochem , Matthieu Rosenfeld

When we study forbidden subgraph conditions guaranteeing graphs to have some properties, a claw (or $K_{1,3}$) frequently appears as one of forbidden subgraphs. Recently, Furuya and Tsuchiya compared two classes generated by different…

Combinatorics · Mathematics 2015-05-05 Guantao Chen , Michitaka Furuya , Songling Shan , Shoichi Tsuchiya , Ping Yang

In this paper, we study orthogonal representations of simple graphs $G$ in $\mathbb{R}^d$ from an algebraic perspective in case $d = 2$. Orthogonal representations of graphs, introduced by Lov\'asz, are maps from the vertex set to…

Commutative Algebra · Mathematics 2014-11-14 Jürgen Herzog , Antonio Macchia , Sara Saeedi Madani , Volkmar Welker

Let F be a set of ordered patterns, i.e., graphs whose vertices are linearly ordered. An F-free ordering of the vertices of a graph H is a linear ordering of V(H) such that none of patterns in F occurs as an induced ordered subgraph. We…

Discrete Mathematics · Computer Science 2014-08-08 Pavol Hell , Bojan Mohar , Arash Rafiey

Let k be a natural number. We introduce k-threshold graphs. We show that there exists an O(n^3) algorithm for the recognition of k-threshold graphs for each natural number k. k-Threshold graphs are characterized by a finite collection of…

Combinatorics · Mathematics 2015-03-19 Ling-Ju Hung , Ton Kloks , Fernando Villaamil

Klavik et al. [arXiv:1207.6960] recently introduced a generalization of recognition called the bounded representation problem which we study for the classes of interval and proper interval graphs. The input gives a graph G and in addition…

Discrete Mathematics · Computer Science 2013-09-06 Martin Balko , Pavel Klavík , Yota Otachi