scholarly journals On a greedy 2-matching algorithm and Hamilton cycles in random graphs with minimum degree at least three

2012 ◽  
Vol 45 (3) ◽  
pp. 443-497 ◽  
Author(s):  
Alan Frieze
2021 ◽  
Vol 94 (12) ◽  
Author(s):  
Till Kahlke ◽  
Martin Fränzle ◽  
Alexander K. Hartmann

Abstract We study numerically the maximum z-matching problems on ensembles of bipartite random graphs. The z-matching problems describes the matching between two types of nodes, users and servers, where each server may serve up to z users at the same time. Using a mapping to standard maximum-cardinality matching, and because for the latter there exists a polynomial-time exact algorithm, we can study large system sizes of up to $$10^6$$ 10 6 nodes. We measure the capacity and the energy of the resulting optimum matchings. First, we confirm previous analytical results for bipartite regular graphs. Next, we study the finite-size behaviour of the matching capacity and find the same scaling behaviour as before for standard matching, which indicates the universality of the problem. Finally, we investigate for bipartite Erdős–Rényi random graphs the saturability as a function of the average degree, i.e. whether the network allows as many customers as possible to be served, i.e. exploiting the servers in an optimal way. We find phase transitions between unsaturable and saturable phases. These coincide with a strong change of the running time of the exact matching algorithm, as well with the point where a minimum-degree heuristic algorithm starts to fail. Graphical Abstract


2000 ◽  
Vol 34 (1) ◽  
pp. 42-59 ◽  
Author(s):  
B. Bollob�s ◽  
C. Cooper ◽  
T. I. Fenner ◽  
A. M. Frieze

2019 ◽  
Vol 29 (1) ◽  
pp. 113-127
Author(s):  
Rajko Nenadov ◽  
Nemanja Škorić

AbstractGiven graphs G and H, a family of vertex-disjoint copies of H in G is called an H-tiling. Conlon, Gowers, Samotij and Schacht showed that for a given graph H and a constant γ>0, there exists C>0 such that if $p \ge C{n^{ - 1/{m_2}(H)}}$ , then asymptotically almost surely every spanning subgraph G of the random graph 𝒢(n, p) with minimum degree at least $\delta (G) \ge (1 - \frac{1}{{{\chi _{{\rm{cr}}}}(H)}} + \gamma )np$ contains an H-tiling that covers all but at most γn vertices. Here, χcr(H) denotes the critical chromatic number, a parameter introduced by Komlós, and m2(H) is the 2-density of H. We show that this theorem can be bootstrapped to obtain an H-tiling covering all but at most $\gamma {(C/p)^{{m_2}(H)}}$ vertices, which is strictly smaller when $p \ge C{n^{ - 1/{m_2}(H)}}$ . In the case where H = K3, this answers the question of Balogh, Lee and Samotij. Furthermore, for an arbitrary graph H we give an upper bound on p for which some leftover is unavoidable and a bound on the size of a largest H -tiling for p below this value.


2012 ◽  
pp. 59-96 ◽  
Author(s):  
Béla Bollobás ◽  
T. I. Fenner ◽  
A. M. Frieze

2016 ◽  
Vol 49 (4) ◽  
pp. 635-668 ◽  
Author(s):  
Asaf Ferber ◽  
Michael Krivelevich ◽  
Benny Sudakov ◽  
Pedro Vieira

COMBINATORICA ◽  
2014 ◽  
Vol 34 (5) ◽  
pp. 573-596 ◽  
Author(s):  
Dan Hefetz ◽  
Daniela Kühn ◽  
John Lapinskas ◽  
Deryk Osthus

2018 ◽  
Vol 27 (4) ◽  
pp. 475-495
Author(s):  
JOSEPH BRIGGS ◽  
ALAN FRIEZE ◽  
MICHAEL KRIVELEVICH ◽  
PO-SHEN LOH ◽  
BENNY SUDAKOV

It is known that w.h.p. the hitting time τ2σ for the random graph process to have minimum degree 2σ coincides with the hitting time for σ edge-disjoint Hamilton cycles [4, 9, 13]. In this paper we prove an online version of this property. We show that, for a fixed integer σ ⩾ 2, if random edges of Kn are presented one by one then w.h.p. it is possible to colour the edges online with σ colours so that at time τ2σ each colour class is Hamiltonian.


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