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Existence of a perfect matching in a random bipartite digraph with bipartition $(V_1, V_2)$, $|V_i|=n$, is studied. The graph is generated in two rounds of random selections of a potential matching partner such that the average number of…

Combinatorics · Mathematics 2019-03-15 Michal Karoński , Ed Overman , Boris Pittel

Lovasz and Plummer conjectured in the 1970's that cubic bridgeless graphs have exponentially many perfect matchings. This conjecture has been verified for bipartite graphs by Voorhoeve in 1979, and for planar graphs by Chudnovsky and…

Combinatorics · Mathematics 2012-06-08 L. Esperet , F. Kardos , D. Kral'

We prove that a fractional perfect matching in a non-bipartite graph can be written, in polynomial time, as a convex combination of perfect matchings. This extends the Birkhoff-von Neumann Theorem from bipartite to non-bipartite graphs. The…

Data Structures and Algorithms · Computer Science 2020-10-16 Vijay V. Vazirani

In this paper we consider the well-studied problem of finding a perfect matching in a d-regular bipartite graph on 2n nodes with m=nd edges. The best-known algorithm for general bipartite graphs (due to Hopcroft and Karp) takes time…

Data Structures and Algorithms · Computer Science 2010-11-15 Ashish Goel , Michael Kapralov , Sanjeev Khanna

We characterize hyperfinite bipartite graphings that admit measurable perfect matchings. In particular, we prove that every regular hyperfinite bipartite graphing admits a measurable perfect matching if it is one-ended or the degree is odd.…

Combinatorics · Mathematics 2022-07-01 Matthew Bowen , Gabor Kun , Marcin Sabok

Matching minors are a specialisation of minors fit for the study of graph with perfect matchings. The notion of matching minors has been used to give a structural description of bipartite graphs on which the number of perfect matchings can…

Combinatorics · Mathematics 2021-06-03 Archontia C Giannopoulou , Stephan Kreutzer , Sebastian Wiederrecht

A graph is {\em perfect} if, in all its induced subgraphs, the size of a largest clique is equal to the chromatic number. Examples of perfect graphs include bipartite graphs, line graphs of bipartite graphs and the complements of such…

Combinatorics · Mathematics 2007-05-23 Gérard Cornuéjols

An $r$-graph is an $r$-regular graph with no odd cut of size less than $r$. A well-celebrated result due to Lov\'asz says that for such graphs the linear system $Ax = \textbf{1}$ has a solution in $\mathbb{Z}/2$, where $A$ is the $0,1$ edge…

Combinatorics · Mathematics 2024-12-10 Olha Silina

We show that the perfect matching problem in general graphs is in Quasi-NC. That is, we give a deterministic parallel algorithm which runs in $O(\log^3 n)$ time on $n^{O(\log^2 n)}$ processors. The result is obtained by a derandomization of…

Computational Complexity · Computer Science 2018-09-14 Ola Svensson , Jakub Tarnawski

We show that each perfect matching in a bipartite graph $G$ intersects at least half of the perfect matchings in $G$. This result has equivalent formulations in terms of the permanent of the adjacency matrix of a graph, and in terms of…

Combinatorics · Mathematics 2019-10-14 Matija Bucic , Pat Devlin , Mo Hendon , Dru Horne , Ben Lund

Extending the notion of (random) $k$-out graphs, we consider when the $k$-out hypergraph is likely to have a perfect fractional matching. In particular, we show that for each $r$ there is a $k=k(r)$ such that the $k$-out $r$-uniform…

Combinatorics · Mathematics 2017-03-13 Pat Devlin , Jeff Kahn

We prove that any non-amenable Cayley graph admits a factor of IID perfect matching. We also show that any connected d-regular vertex tran- sitive graph admits a perfect matching. The two results together imply that every Cayley graph…

Combinatorics · Mathematics 2012-11-13 Endre Csoka , Gabor Lippner

In this paper we consider a simple Markov chain for bipartite graphs with given degree sequence on $n$ vertices. We show that the mixing time of this Markov chain is bounded above by a polynomial in $n$ in case of {\em semi-regular} degree…

Combinatorics · Mathematics 2021-01-01 Péter L. Erdös , Istán Miklós , Lajos Soukup

Lovasz and Plummer conjectured that there exists a fixed positive constant c such that every cubic n-vertex graph with no cutedge has at least 2^(cn) perfect matchings. Their conjecture has been verified for bipartite graphs by Voorhoeve…

Combinatorics · Mathematics 2022-10-05 Sang-il Oum

The 1970s conjecture of Lov\'asz and Plummer that the number of perfect matchings in any $3$-regular graph is exponential in the number of vertices was proved in 2011 by Esperet, Kardo\v{s}, King, Kr\'al', and Norine. We give the exact…

Combinatorics · Mathematics 2020-03-26 R. S. Lekshmi , Douglas B. West

A $d$-regular graph on $n$ nodes has at most $T_{\max} = \frac{n}{3} \tbinom{d}{2}$ triangles. We compute the leading asymptotics of the probability that a large random $d$-regular graph has at least $c \cdot T_{\max}$ triangles, and…

Combinatorics · Mathematics 2021-04-16 Pim van der Hoorn , Gabor Lippner , Elchanan Mossel

Haxell's condition is a natural hypergraph analog of Hall's condition, which is a well-known necessary and sufficient condition for a bipartite graph to admit a perfect matching. That is, when Haxell's condition holds it forces the…

Data Structures and Algorithms · Computer Science 2016-12-06 Chidambaram Annamalai

We investigate the asymptotic structure of a random perfect graph $P_n$ sampled uniformly from the perfect graphs on vertex set $\{1,\ldots,n\}$. Our approach is based on the result of Pr\"omel and Steger that almost all perfect graphs are…

Combinatorics · Mathematics 2017-09-07 Colin McDiarmid , Nikola Yolov

We show that efficient approximate sampling algorithms, combined with a slow exponential time oracle for computing its output distribution, can be combined into constructing efficient perfect samplers, which sample exactly from a target…

Computational Complexity · Computer Science 2024-12-09 Andreas Göbel , Jingcheng Liu , Pasin Manurangsi , Marcus Pappik

Let $n\ge 34$ be an even integer, and $D_n=2\lceil n/4 \rceil-1$. In this paper, we prove that every $\{D_n,\,D_n+1\}$-graph of order $n$ contains $\lceil n/4 \rceil$ disjoint perfect matchings. This result is sharp in the sense that (i)…

Combinatorics · Mathematics 2015-09-03 Hongliang Lu , David G. L. Wang