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Let ${\rm dim}(G)$ and $D(G)$ respectively denote the metric dimension and the distinguishing number of a graph $G$. It is proved that $D(G) \le {\rm dim}(G)+1$ holds for every connected graph $G$. Among trees, exactly paths and stars…

Combinatorics · Mathematics 2025-07-08 Meysam Korivand , Nasrin Soltankhah , Sandi Klavžar

A graph $G$ with four or more vertices is called bicritical if the removal of any pair of distinct vertices of $G$ results in a graph with a perfect matching. A bicritical graph is minimal if the deletion of each edge results in a…

Combinatorics · Mathematics 2024-10-15 Jing Guo , Hailun Wu , Heping Zhang

In this paper we characterize the unique graph whose algebraic connectivity is minimum among all connected graphs with given order and fixed matching number or edge covering number, and present two lower bounds for the algebraic…

Combinatorics · Mathematics 2017-09-07 Jing Xu , Yi-Zheng Fan , Ying-Ying Tan

A matching cut in a graph G is an edge cut of G that is also a matching. This short survey gives an overview of old and new results and open problems for Maximum Matching Cut, which is to determine the size of a largest matching cut in a…

Combinatorics · Mathematics 2023-12-21 Van Bang Le , Felicia Lucke , Daniël Paulusma , Bernard Ries

We prove that an inseparable graph can have any positive number of cycles with the six exceptions 2, 4, 5, 8, 9, 16, and that an inseparable cubic graph has the additional exceptions 1 and 13. The exceptions for simple inseparable cubic…

Combinatorics · Mathematics 2025-12-01 Ryan McCulloch , Brendan D. McKay , Alireza Salahshoori , Thomas Zaslavsky

Let $G$ be a connected graph with vertex set $V(G)=\{v_1,v_2,...,v_{\nu}\}$, which may have multiple edges but have no loops, and $2\leq d_G(v_i)\leq 3$ for $i=1,2,...,\nu$, where $d_G(v)$ denotes the degree of vertex $v$ of $G$. We show…

Combinatorics · Mathematics 2009-06-23 Weigen Yan , Fuji Zhang

A graph $G$ is {\em matching-decyclable} if it has a matching $M$ such that $G-M$ is acyclic. Deciding whether $G$ is matching-decyclable is an NP-complete problem even if $G$ is 2-connected, planar, and subcubic. In this work we present…

Discrete Mathematics · Computer Science 2023-06-22 Fábio Protti , Uéverton S. Souza

A subset of vertices in a graph $G$ is considered a maximal dissociation set if it induces a subgraph with vertex degree at most 1 and it is not contained within any other dissociation sets. In this paper, it is shown that for $n\geq 3$,…

Combinatorics · Mathematics 2024-11-06 Junxia Zhang , Xiangyu Ren , Maoqun Wang

A graph $G$ is equimatchable if any matching in $G$ is a subset of a maximum-size matching. It is known that any $2$-connected equimatchable graph is either bipartite or factor-critical. We prove that for any vertex $v$ of a $2$-connected…

Combinatorics · Mathematics 2013-12-13 Eduard Eiben , Michal Kotrbčík

In 1979, Nishizeki and Baybars showed that every planar graph with minimum degree 3 has a matching of size $\frac{n}{3}+c$ (where the constant $c$ depends on the connectivity), and even better bounds hold for planar graphs with minimum…

Discrete Mathematics · Computer Science 2020-02-21 Therese Biedl , John Wittnebel

For a graph \(G\), let $avm(G)$ denote the average size of its maximal matchings. This parameter was introduced by Engbers and Erey in the study of extremal problems for maximal matchings, and they asked for extensions from trees and…

Combinatorics · Mathematics 2026-05-01 Kai Zhang

We discuss the question whether the existence of perfect matchings in a cubic graph can be seen from the spectrum of its adjacency matrix. For regular graphs in general and for three edge-disjoint perfect matchings in a cubic graph (that…

Combinatorics · Mathematics 2026-01-08 Willem H. Haemers

A packing $k$-coloring of a graph $G$ is a partition of $V(G)$ into sets $V_1,\ldots,V_k$ such that for each $1\leq i\leq k$ the distance between any two distinct $x,y\in V_i$ is at least $i+1$. The packing chromatic number, $\chi_p(G)$, of…

Combinatorics · Mathematics 2017-03-31 József Balogh , Alexandr Kostochka , Xujun Liu

Let $G$ be a distance-regular graph of order $v$ and size $e$. In this paper, we show that the max-cut in $G$ is at most $e(1-1/g)$, where $g$ is the odd girth of $G$. This result implies that the independence number of $G$ is at most…

Combinatorics · Mathematics 2017-01-09 Sebastian M. Cioabă , Jack H. Koolen , Weiqiang Li

We introduce new sufficient conditions for intrinsic knotting and linking. A graph on n vertices with at least 4n-9 edges is intrinsically linked. A graph on n vertices with at least 5n-14 edges is intrinsically knotted. We also classify…

Geometric Topology · Mathematics 2007-05-23 J. Campbell , T. W. Mattman , R. Ottman , J. Pyzer , M. Rodrigues , S. Williams

A matchstick graph is a plane graph with edges drawn as unit-distance line segments. Harborth introduced these graphs in 1981 and conjectured that the maximum number of edges for a matchstick graph on $n$ vertices is $\lfloor…

Combinatorics · Mathematics 2023-06-16 Jérémy Lavollée , Konrad Swanepoel

For an edge-colored graph $G$, we call an edge-cut $M$ of $G$ monochromatic if the edges of $M$ are colored with the same color. The graph $G$ is called monochromatic disconnected if any two distinct vertices of $G$ are separated by a…

Combinatorics · Mathematics 2020-09-07 Ping Li , Xueliang Li

Consider the family of all finite graphs with maximum degree $\Delta(G)<d$ and matching number $\nu(G)<m$. In this paper we give a new proof to obtain the exact upper bound for the number of edges in such graphs and also characterize all…

Combinatorics · Mathematics 2007-05-23 Niranjan Balachandran , Niraj Khare

In this paper, we prove two lower bounds for the maximum matching size in an arbitrary undirected graph. Despite their simplicity, these results are not widely known. This article aims to bring pleasure to the reader by giving short…

Combinatorics · Mathematics 2024-05-30 Fedor Kuyanov

A graph $G=(V,E)$ is called a unit-distance graph in the plane if there is an injective embedding of $V$ in the plane such that every pair of adjacent vertices are at unit distance apart. If additionally the corresponding edges are…

Combinatorics · Mathematics 2014-01-09 Sascha Kurz