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Topological drawings are natural representations of graphs in the plane, where vertices are represented by points, and edges by curves connecting the points. Topological drawings of complete graphs and of complete bipartite graphs have been…

Computational Geometry · Computer Science 2017-02-10 Jean Cardinal , Stefan Felsner

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

We consider the problem of counting matchings in planar graphs. While perfect matchings in planar graphs can be counted by a classical polynomial-time algorithm, the problem of counting all matchings (possibly containing unmatched vertices,…

Computational Complexity · Computer Science 2016-07-28 Radu Curticapean

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

The decision problem of perfect matchings in uniform hypergraphs is famously an NP-complete problem. It has been shown by Keevash--Knox--Mycroft [STOC, 2013] that for every $\varepsilon>0$, such decision problem restricted to $k$-uniform…

Combinatorics · Mathematics 2025-10-23 Jie Han , Jingwen Zhao

We propose efficient algorithms for enumerating the notorious combinatorial structures of maximal planar graphs, called canonical orderings and Schnyder woods, and the related classical graph drawings by de Fraysseix, Pach, and Pollack…

Data Structures and Algorithms · Computer Science 2023-10-04 Giordano Da Lozzo , Giuseppe Di Battista , Fabrizio Frati , Fabrizio Grosso , Maurizio Patrignani

We determine the minimum degree sum of two adjacent vertices that ensures a perfect matching in a 3-graph without isolated vertex. More precisely, suppose that $H$ is a 3-uniform hypergraph whose order $n$ is sufficiently large and…

Combinatorics · Mathematics 2017-10-16 Yi Zhang , Yi Zhao , Mei Lu

In 1994, it was conjectured by Fan and Raspaud that every simple bridgeless cubic graph has three perfect matchings whose intersection is empty. In this paper we answer a question recently proposed by Mkrtchyan and Vardanyan, by giving an…

Combinatorics · Mathematics 2022-03-22 Giuseppe Mazzuoccolo , Jean Paul Zerafa

As training deep learning models on large dataset takes a lot of time and resources, it is desired to construct a small synthetic dataset with which we can train deep learning models sufficiently. There are recent works that have explored…

Machine Learning · Computer Science 2022-09-12 Wei Jin , Xianfeng Tang , Haoming Jiang , Zheng Li , Danqing Zhang , Jiliang Tang , Bing Yin

We propose a weighted common subgraph (WCS) matching algorithm to find the most similar subgraphs in two labeled weighted graphs. WCS matching, as a natural generalization of the equal-sized graph matching or subgraph matching, finds wide…

Data Structures and Algorithms · Computer Science 2014-11-05 Xu Yang , Hong Qiao , Zhi-Yong Liu

We study the perfect matching lattice of a matching covered graph $G$, generated by the incidence vectors of its perfect matchings. Building on results of Lov\'asz and de Carvalho, Lucchesi, and Murty, we give a polynomial-time algorithm…

Combinatorics · Mathematics 2025-11-07 Olha Silina

Let $n \equiv 0\, (\, \text{mod } 3\,)$ and $H_{n, n/3}^2$ be the 3-graph of order $n$, whose vertex set is partitioned into two sets $S$ and $T$ of size $\frac{1}{3}n+1$ and $\frac{2}{3}n -1$, respectively, and whose edge set consists of…

Combinatorics · Mathematics 2024-01-09 Yan Wang , Yi Zhang

A perfect matching in a hypergraph is a set of edges that partition the set of vertices. We study the complexity of deciding the existence of a perfect matching in orderable and separable hypergraphs. We show that the class of orderable…

Combinatorics · Mathematics 2022-02-03 Shmuel Onn

Inspired by applications of perfect graphs in combinatorial optimization, Chv\'{a}tal defined t-perfect graphs in 1970s. The long efforts of characterizing t-perfect graphs started immediately, but embarrassingly, even a working conjecture…

Combinatorics · Mathematics 2021-05-03 Yixin Cao , Shenghua Wang

We consider, for complete bipartite graphs, the convex hulls of characteristic vectors of all matchings, extended by a binary entry indicating whether the matching contains two specific edges. These polytopes are associated to the quadratic…

Discrete Mathematics · Computer Science 2019-04-09 Matthias Walter

A 2-join is an edge cutset that naturally appears in decomposition of several classes of graphs closed under taking induced subgraphs, such as perfect graphs and claw-free graphs. In this paper we construct combinatorial polynomial time…

Discrete Mathematics · Computer Science 2016-03-27 Nicolas Trotignon , Kristina Vušković

A vertex coloring of a given simple graph $G=(V,E)$ with $k$ colors ($k$-coloring) is a map from its vertex set to the set of integers $\{1,2,3,\dots, k\}$. A coloring is called perfect if the multiset of colors appearing on the neighbours…

Combinatorics · Mathematics 2020-05-29 O. G. Parshina , M. A. Lisitsyna

The perfect matching complex of a simple graph $G$ is a simplicial complex having facets (maximal faces) as the perfect matchings of $G$. This article discusses the perfect matching complex of polygonal line tilings and the $\left(2 \times…

Combinatorics · Mathematics 2025-04-08 Himanshu Chandrakar , Anurag Singh

Graph condensation aims to reduce the size of a large-scale graph dataset by synthesizing a compact counterpart without sacrificing the performance of Graph Neural Networks (GNNs) trained on it, which has shed light on reducing the…

Machine Learning · Computer Science 2024-06-19 Yuchen Zhang , Tianle Zhang , Kai Wang , Ziyao Guo , Yuxuan Liang , Xavier Bresson , Wei Jin , Yang You

The perfect matching polytope, i.e. the convex hull of (incidence vectors of) perfect matchings of a graph is used in many combinatorial algorithms. Kotzig, Lov\'asz and Plummer developed a decomposition theory for graphs with perfect…

Combinatorics · Mathematics 2019-03-01 Isabel Beckenbach , Meike Hatzel , Sebastian Wiederrecht