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Here we prove that counting maximum matchings in planar, bipartite graphs is #P-complete. This is somewhat surprising in the light that the number of perfect matchings in planar graphs can be computed in polynomial time. We also prove that…

Computational Complexity · Computer Science 2021-03-09 Istvan Miklos , Miklos Kresz

We design a fully polynomial time approximation scheme (FPTAS) for counting the number of matchings (packings) in arbitrary 3-uniform hypergraphs of maximum degree three, referred to as $(3,3)$-hypergraphs. It is the first polynomial time…

Combinatorics · Mathematics 2017-10-26 Andrzej Dudek , Marek Karpinski , Andrzej Ruciński , Edyta Szymańska

In 1988, Vazirani gave an NC algorithm for computing the number of perfect matchings in $K_{3,3}$-minor-free graphs by building on Kasteleyn's scheme for planar graphs, and stated that this "opens up the possibility of obtaining an NC…

Data Structures and Algorithms · Computer Science 2021-06-29 David Eppstein , Vijay V. Vazirani

We present a $(1- \varepsilon)$-approximation algorithms for maximum cardinality matchings in disk intersection graphs -- all with near linear running time. We also present estimation algorithm that returns $(1\pm…

Computational Geometry · Computer Science 2022-03-17 Sariel Har-Peled , Everett Yang

We consider 3-regular planar matchstick graphs, i.e. those which have a planar embedding such that all edge lengths are equal, with given girth g. For girth 3 it is known that such graphs exist if and only if the number of vertices n is an…

Combinatorics · Mathematics 2014-01-20 Sascha Kurz , Giuseppe Mazzuoccolo

A planar orthogonal drawing {\Gamma} of a connected planar graph G is a geometric representation of G such that the vertices are drawn as distinct points of the plane, the edges are drawn as chains of horizontal and vertical segments, and…

Computational Geometry · Computer Science 2025-02-06 Walter Didimo , Giuseppe Liotta , Giacomo Ortali , Maurizio Patrignani

We study a competitive optimization version of $\alpha'(G)$, the maximum size of a matching in a graph $G$. Players alternate adding edges of $G$ to a matching until it becomes a maximal matching. One player (Max) wants that matching to be…

Combinatorics · Mathematics 2015-08-06 Daniel W. Cranston , William B. Kinnersley , Suil O. , Douglas B. West

In this paper, we study the maximum matching problem in RDV graphs, i.e., graphs that are vertex-intersection graphs of downward paths in a rooted tree. We show that this problem can be reduced to a problem of testing (repeatedly) whether a…

Computational Geometry · Computer Science 2024-06-07 Therese Biedl , Prashant Gokhale

We present an algorithm for finding a perfect matching in a $3$-edge-connected cubic graph that intersects every $3$-edge cut in exactly one edge. Specifically, we propose an algorithm with a time complexity of $O(n \log^4 n)$, which…

Data Structures and Algorithms · Computer Science 2025-07-03 Babak Ghanbari , Robert Šámal

The problem of finding a maximum size matching in a graph (known as the maximum matching problem) is one of the most classical problems in computer science. Despite a significant body of work dedicated to the study of this problem in the…

Data Structures and Algorithms · Computer Science 2021-09-14 Moran Feldman , Ariel Szarf

For a graph $G$ define the parameters $\ell(G)$ and $L(G)$ as the minimum and maximum value of $\nu(G\backslash F)$, where $F$ is a maximum matching of $G$ and $\nu(G)$ is the matching number of $G$. In this paper, we show that there is a…

Combinatorics · Mathematics 2025-04-29 Vahan Mkrtchyan

In the k-Apex problem the task is to find at most k vertices whose deletion makes the given graph planar. The graphs for which there exists a solution form a minor closed class of graphs, hence by the deep results of Robertson and Seymour,…

Data Structures and Algorithms · Computer Science 2008-12-31 Dániel Marx , Ildikó Schlotter

In 2016, Chandrasekaran, V\'egh, and Vempala published a method to solve the minimum-cost perfect matching problem on an arbitrary graph by solving a strictly polynomial number of linear programs. However, their method requires a strong…

Combinatorics · Mathematics 2019-08-30 Amber Q Chen , Kevin K. H. Cheung , P. Michael Kielstra , Andrew Winn

In this paper we present an efficiently scaling quantum algorithm which finds the size of the maximum common edge subgraph for a pair of arbitrary graphs and thus provides a meaningful measure of graph similarity. The algorithm makes use of…

Quantum Physics · Physics 2018-10-04 M. Chiew , K. de Lacy , C. H. Yu , S. Marsh , J. B. Wang

A bottleneck plane perfect matching of a set of $n$ points in $\mathbb{R}^2$ is defined to be a perfect non-crossing matching that minimizes the length of the longest edge; the length of this longest edge is known as {\em bottleneck}. The…

Computational Geometry · Computer Science 2015-08-25 A. Karim Abu-Affash , Ahmad Biniaz , Paz Carmi , Anil Maheshwari , Michiel Smid

Counting maximum matchings in a graph is of great interest in statistical mechanics, solid-state chemistry, theoretical computer science, mathematics, among other disciplines. However, it is a challengeable problem to explicitly determine…

Combinatorics · Mathematics 2023-06-26 Tingzeng Wu , Xiaolin Zeng , Huazhong Lv

The Maximum Induced Matching problem asks to find the maximum $k$ such that, given a graph $G=(V,E)$, can we find a subset of vertices $S$ of size $k$ for which every vertices $v$ in the induced graph $G[S]$ has exactly degree $1$. In this…

Data Structures and Algorithms · Computer Science 2022-01-11 Gordon Hoi , Ammar Fathin Sabili , Frank Stephan

In this paper, we present two main results. First, by only one conjecture (Conjecture 2.9) for recognizing a vertex symmetric graph, which is the hardest task for our problem, we construct an algorithm for finding an isomorphism between two…

Data Structures and Algorithms · Computer Science 2017-06-29 Caishi Fang

It follows from known results that every regular tripartite hypergraph of positive degree, with $n$ vertices in each class, has matching number at least $n/2$. This bound is best possible, and the extremal configuration is unique. Here we…

Combinatorics · Mathematics 2017-01-24 Penny Haxell , Lothar Narins

Let $A$ and $B$ be two point sets in the plane of sizes $r$ and $n$ respectively (assume $r \leq n$), and let $k$ be a parameter. A matching between $A$ and $B$ is a family of pairs in $A \times B$ so that any point of $A \cup B$ appears in…

Data Structures and Algorithms · Computer Science 2019-03-25 Pankaj K. Agarwal , Hsien-Chih Chang , Allen Xiao