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A $k$-ranking is a vertex $k$-coloring such that if two vertices have the same color any path connecting them contains a vertex of larger color. The rank number of a graph is smallest $k$ such that $G$ has a $k$-ranking. For certain graphs…

Combinatorics · Mathematics 2017-02-08 Rigoberto Florez , Darren A. Narayan

A matching of a graph is a subset of edges no two of which share a common vertex, and a maximum matching is a matching of maximum cardinality. In a $b$-matching every vertex $v$ has an associated bound $b_v$, and a maximum $b$-matching is a…

Data Structures and Algorithms · Computer Science 2019-04-24 Yuval Emek , Shay Kutten , Mordechai Shalom , Shmuel Zaks

The maximum matching width is a width-parameter that is defined on a branch-decomposition over the vertex set of a graph. The size of a maximum matching in the bipartite graph is used as a cut-function. In this paper, we characterize the…

Combinatorics · Mathematics 2016-06-24 Jisu Jeong , Seongmin Ok , Geewon Suh

We introduce the matching measure of a finite graph as the uniform distribution on the roots of the matching polynomial of the graph. We analyze the asymptotic behavior of the matching measure for graph sequences with bounded degree. A…

Combinatorics · Mathematics 2021-08-31 Miklos Abért , Péter Csikvári , Péter Frenkel , Gábor Kun

A topological graph is \emph{$k$-quasi-planar} if it does not contain $k$ pairwise crossing edges. A topological graph is \emph{simple} if every pair of its edges intersect at most once (either at a vertex or at their intersection). In…

Combinatorics · Mathematics 2015-03-19 Andrew Suk

A bisection in a graph is a cut in which the number of vertices in the two parts differ by at most 1. In this paper, we give lower bounds for the maximum weight of bisections of edge-weighted graphs with bounded maximum degree. Our results…

Combinatorics · Mathematics 2024-01-23 Stefanie Gerke , Gregory Gutin , Anders Yeo , Yacong Zhou

Graph matching, also known as network alignment, refers to finding a bijection between the vertex sets of two given graphs so as to maximally align their edges. This fundamental computational problem arises frequently in multiple fields…

Data Structures and Algorithms · Computer Science 2021-08-10 Cheng Mao , Mark Rudelson , Konstantin Tikhomirov

The subgraph number of a vertex in a graph is defined as the number of connected subgraphs containing that vertex. The graph and its vertex which correspond to the minimum subgraph number among all graphs on $n$ vertices and $k$ cut…

Combinatorics · Mathematics 2025-08-11 Dinesh Pandey , Peruvemba Sundaram Ravi

In this paper we study conditions which guarantee the existence of perfect matchings and perfect fractional matchings in uniform hypergraphs. We reduce this problem to an old conjecture by Erd\H{o}s on estimating the maximum number of edges…

Combinatorics · Mathematics 2012-02-01 Noga Alon , Peter Frankl , Hao Huang , Vojtech Rodl , Andrzej Rucinski , Benny Sudakov

Friedland's Lower Matching Conjecture asserts that if $G$ is a $d$--regular bipartite graph on $v(G)=2n$ vertices, and $m_k(G)$ denotes the number of matchings of size $k$, then $$m_k(G)\geq {n \choose…

Combinatorics · Mathematics 2017-04-13 Péter Csikvári

Let $G=(V,E)$ be an undirected graph without loops and multiple edges. A subset $C\subseteq V$ is called \emph{identifying} if for every vertex $x\in V$ the intersection of $C$ and the closed neighbourhood of $x$ is nonempty, and these…

Combinatorics · Mathematics 2009-02-04 Sylvain Gravier , Svante Janson , Tero Laihonen , Sanna Ranto

Let $f(n)$ be the smallest number such that every collection of $n$ matchings, each of size at least $f(n)$, in a bipartite graph, has a full rainbow matching. Generalizing famous conjectures of Ryser, Brualdi and Stein, Aharoni and Berger…

Combinatorics · Mathematics 2017-02-24 Ron Aharoni , Dani Kotlar , Ran Ziv

We give efficient distributed algorithms for the minimum vertex cover problem in bipartite graphs in the CONGEST model. From K\H{o}nig's theorem, it is well known that in bipartite graphs the size of a minimum vertex cover is equal to the…

Data Structures and Algorithms · Computer Science 2020-11-20 Salwa Faour , Fabian Kuhn

Mader proved that for $k\geq 2$ and $n\geq 2k$, every $n$-vertex graph with no $(k+1)$-connected subgraphs has at most $(1+\frac{1}{\sqrt{2}})k(n-k)$ edges. He also conjectured that for $n$ large with respect to $k$, every such graph has at…

Combinatorics · Mathematics 2017-05-08 Anton Bernshteyn , Alexandr Kostochka

Given a pair of graphs with the same number of vertices, the inexact graph matching problem consists in finding a correspondence between the vertices of these graphs that minimizes the total number of induced edge disagreements. We study…

Machine Learning · Statistics 2020-07-06 Jesús Arroyo , Daniel L. Sussman , Carey E. Priebe , Vince Lyzinski

The cage problem concerns finding $(k,g)$-graphs, which are $k$-regular graphs with girth $g$, of the smallest possible number of vertices. The central goal is to determine $n(k,g)$, the minimum order of such a graph, and to identify…

Combinatorics · Mathematics 2025-11-11 Geoffrey Exoo , Jan Goedgebeur , Jorik Jooken , Louis Stubbe , Tibo Van den Eede

A spectral characterization of the matching number (the size of a maximum matching) of a graph is given. More precisely, it is shown that the graphs G of order n whose matching number is k are precisely those graphs with the maximum skew…

Combinatorics · Mathematics 2016-02-12 Keivan Hassani Monfared , Sudipta Mallik

We prove tight upper bounds on the logarithmic derivative of the independence and matching polynomials of d-regular graphs. For independent sets, this theorem is a strengthening of the results of Kahn, Galvin and Tetali, and Zhao showing…

Combinatorics · Mathematics 2019-11-04 Ewan Davies , Matthew Jenssen , Will Perkins , Barnaby Roberts

A topological graph drawn on a cylinder whose base is horizontal is \emph{angularly monotone} if every vertical line intersects every edge at most once. Let $c(n)$ denote the maximum number $c$ such that every simple angularly monotone…

Combinatorics · Mathematics 2013-07-17 Radoslav Fulek

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. $1$- and $2$-factor-critical graphs are the well-known factor-critical and…

Combinatorics · Mathematics 2022-07-08 Jing Guo , Heping Zhang