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Given a non-trivial graph $G$, the minimum cardinality of a set of edges $F$ in $G$ such that $\chi'(G \setminus F)<\chi'(G)$ is called the chromatic edge stability index of $G$, denoted by $es_{\chi'}(G)$, and such a (smallest) set $F$ is…

We characterize the vertices belonging to all minimum dominating sets, to some minimum dominating sets but not all, and to no minimum dominating set. We refine this characterization for some well studied sub-classes of graphs: chordal,…

Combinatorics · Mathematics 2021-12-14 Valentin Bouquet , François Delbot , Christophe Picouleau

An immersion of a graph H in another graph G is a one-to-one mapping phi:V(H)->V(G) and a collection of edge-disjoint paths in G, one for each edge of H, such that the path P_{uv} corresponding to the edge uv has endpoints phi(u) and…

Combinatorics · Mathematics 2015-12-03 Zdeněk Dvořák , Liana Yepremyan

A graph is intrinsically knotted if every embedding contains a knotted cycle. It is known that intrinsically knotted graphs have at least 21 edges and that the KS graphs, $K_7$ and the 13 graphs obtained from $K_7$ by $\nabla Y$ moves, are…

Geometric Topology · Mathematics 2014-11-10 Hyoungjun Kim , Thomas Mattman , Seungsang Oh

In this paper uniquely list colorable graphs are studied. A graph G is called to be uniquely k-list colorable if it admits a k-list assignment from which G has a unique list coloring. The minimum k for which G is not uniquely k-list…

Combinatorics · Mathematics 2008-01-03 Ch. Eslahchi , M. Ghebleh , H. Hajiabolhassan

Recently there has been increased interest in fitting generative graph models to real-world networks. In particular, Bl\"asius et al. have proposed a framework for systematic evaluation of the expressivity of random graph models. We extend…

Social and Information Networks · Computer Science 2024-05-14 Benjamin Dayan , Marc Kaufmann , Ulysse Schaller

A graph $G$ of order $n$ is said to be $k$-factor-critical for integers $1\leq k < n$, if the removal of any $k$ vertices results in a graph with a perfect matching. A $k$-factor-critical graph $G$ is called minimal if for any edge $e\in…

Combinatorics · Mathematics 2022-11-08 Jing Guo , Heping Zhang

Chirality refers to the asymmetry of objects that cannot be superimposed on their mirror image. It is a concept that exists in various scientific fields and has profound consequences. Although these are perhaps most widely recognized within…

Charts are oriented labeled graphs in a disk. Any simple surface braid (2-dimensional braid) can be described by using a chart. Also, a chart represents an oriented closed surface embedded in 4-space. In this paper, we investigate embedded…

Geometric Topology · Mathematics 2024-05-10 Teruo Nagase , Akiko Shima

In this work we investigate the chordality of squares and line graph squares of graphs. We prove a sufficient condition for the chordality of squares of graphs not containing induced cycles of length at least five. Moreover, we characterize…

Combinatorics · Mathematics 2017-04-04 Robert Scheidweiler , Sebastian Wiederrecht

A connected $k$-chromatic graph $G$ is said to be {\it double-critical} if for all edges $uv$ of $G$ the graph $G - u - v$ is $(k-2)$-colourable. A longstanding conjecture of Erd\H{o}s and Lov\'asz states that the complete graphs are the…

Combinatorics · Mathematics 2010-08-02 Anders Sune Pedersen

An injective edge-coloring $c$ of a graph $G$ is an edge-coloring such that if $e_1$, $e_2$, and $e_3$ are three consecutive edges in $G$ (they are consecutive if they form a path or a cycle of length three), then $e_1$ and $e_3$ receive…

Combinatorics · Mathematics 2020-09-01 Baya Ferdjallah , Samia Kerdjoudj , Andre Raspaud

Molecular representation learning (MRL) is a key step to build the connection between machine learning and chemical science. In particular, it encodes molecules as numerical vectors preserving the molecular structures and features, on top…

Quantitative Methods · Quantitative Biology 2023-11-30 Zhichun Guo , Kehan Guo , Bozhao Nan , Yijun Tian , Roshni G. Iyer , Yihong Ma , Olaf Wiest , Xiangliang Zhang , Wei Wang , Chuxu Zhang , Nitesh V. Chawla

We study several cardinal characteristics of closed graphs G on compact metrizable spaces. In particular, we address the question when it is consistent for the bounding number to be strictly smaller than the smallest size of a set not…

Logic · Mathematics 2020-03-12 Francis Adams , Jindrich Zapletal

We consider the following properties of compact oriented irreducible graph-manifolds: to contain a $\pi_1$-injective surface (immersed, virtually embedded or embedded), be (virtually) fibered over $S^1$, and to carry a metric of nonpositive…

Geometric Topology · Mathematics 2007-05-23 P. Svetlov

We give the classification of all possible G-graphs for any small binary dihedral subgroup G in GL(2,C) and use this classification to give the combinatorial description of the special representations of G in terms of its maximal cyclic…

Algebraic Geometry · Mathematics 2012-08-09 Álvaro Nolla de Celis

This paper presents a first-principle and global perspective of electromagnetic chirality. It follows for this purpose a bottom-up construction, from the description of chiral particles or metaparticles (microscopic scale), through the…

Optics · Physics 2019-04-05 Christophe Caloz , Ari Sihvola

Chiral symmetry, fundamental in the physics of graphene, guarantees the existence of topologically stable doubled Dirac cones and anomalous behaviors of the zero-energy Landau level in magnetic fields. The crucial role is inherited in the…

Mesoscale and Nanoscale Physics · Physics 2013-11-13 Y. Hatsugai , T. Morimoto , T. Kawarabayashi , Y. Hamamoto , H. Aoki

In many biological materials with a hierarchical structure there is an intriguing and unique mechanism responsible for the 'propagation' of order from the molecular to the nano- or micro-scale level. Here we present a much simpler molecular…

We examine graphs that contain a non-trivial link in every embedding into real projective space, using a weaker notion of unlink than was used by Flapan, et al. We call such graphs intrinsically linked in projective space. We fully…