Abstract
A Hamilton cycle in a digraph is a cycle that passes through all the vertices, where all the arcs are oriented in the same direction. The problem of finding Hamilton cycles in directed graphs is well studied and is known to be hard. One of the main reasons for this is that there is no general tool for finding Hamilton cycles in directed graphs comparable to the so-called Posá ‘rotation-extension’ technique for the undirected analogue. Let D(n, p) denote the random digraph on vertex set [n], obtained by adding each directed edge independently with probability p. Here we present a general and a very simple method, using known results, to attack problems of packing and counting Hamilton cycles in random directed graphs, for every edge-probability p > logC(n)/n. Our results are asymptotically optimal with respect to all parameters and apply equally well to the undirected case.
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N. Alon and J. H. Spencer, The Probabilistic Method, third ed., Wiley-Interscience Series in Discrete Mathematics and Optimization, John Wiley & Sons, Inc., Hoboken, NJ, 2008.
S. Ben-Shimon, M. Krivelevich and B. Sudakov, On the resilience of Hamiltonicity and optimal packing of Hamilton cycles in random graphs, SIAM J. Discrete Math. 25 (2011), 1176–1193.
B. Bollobás, The evolution of random graphs, Trans. Amer. Math. Soc. 286 (1984), 257–274.
B. Bollobás and A. M. Frieze, On matchings and Hamiltonian cycles in random graphs, in Random graphs’ 83 (Poznań, 1983), North-Holland Math. Stud., Vol. 118, North-Holland, Amsterdam, 1985, pp. 23–46.
B. Csaba, D. Kühn, A. Lo, D. Osthus and A. Treglown, Proof of the 1-factorization and Hamilton Decomposition Conjectures, Mem. Amer. Math. Soc. 244 (2016).
B. Cuckler, Hamiltonian cycles in regular tournaments, Combin. Probab. Comput. 16 (2007), 239–249.
B. Cuckler and J. Kahn, Hamiltonian cycles in Dirac graphs, Combinatorica 29 (2009), 299–326.
G. A. Dirac, Some theorems on abstract graphs, Proc. London Math. Soc. (3) 2 (1952), 69–81.
G. P. Egorychev, The solution of van der Waerden’s problem for permanents, Adv. in Math. 42 (1981), 299–305.
D. I. Falikman, Proof of the van der Waerden conjecture regarding the permanent of a doubly stochastic matrix, Mathematical Notes 29 (1981), 475–479.
A. Ferber, M. Krivelevich and B. Sudakov, Counting and packing Hamilton cycles in dense graphs and oriented graphs, J. Combin. Theory Ser. B, to appear.
A. Ferber, G. Kronenberg, F. Mousset and C. Shikhelman, Packing a randomly edgecolored random graph with rainbow k-outs, arXiv preprint arXiv:1410.1803 (2014).
A. Ferber, R. Nenadov, U. Peter, A. Noever and N. Škoric, Robust Hamiltonicity of random directed graphs, SODA’ 14.
A. M. Frieze, An algorithm for finding Hamilton cycles in random directed graphs, J. Algorithms 9 (1988), 181–204.
A. Frieze and M. Krivelevich, On two Hamilton cycle problems in random graphs, Israel J. Math. 166 (2008), 221–234.
A. Frieze and S. Suen, Counting the number of Hamilton cycles in random digraphs, Random Structures Algorithms 3 (1992), 235–241.
R. Glebov and M. Krivelevich, On the number of Hamilton cycles in sparse random graphs, SIAM J. Discrete Math. 27 (2013), 27–42.
R. Glebov, M. Krivelevich and T. Szabó, On covering expander graphs by Hamilton cycles, Random Structures Algorithms 44 (2014), 183–200.
D. Hefetz, D. Kühn, J. Lapinskas and D. Osthus, Optimal covers with Hamilton cycles in random graphs, Combinatorica 34 (2014), 573–596.
D. Hefetz, A. Steger and B. Sudakov, Random directed graphs are robustly Hamiltonian, arXiv preprint arXiv:1404.4734 (2014).
S. Janson, The numbers of spanning trees, Hamilton cycles and perfect matchings in a random graph, Combin. Probab. Comput. 3 (1994), 97–126.
S. Janson, T. ’Luczak and A. Rucinski, Random Graphs, Wiley-Interscience Series in Discrete Mathematics and Optimization, Wiley-Interscience, New York, 2000.
R. M. Karp, Reducibility among combinatorial problems, in Complexity of computer computations (Proc. Sympos., IBM Thomas J. Watson Res. Center, Yorktown Heights, N.Y., 1972), Plenum, New York, 1972, pp. 85–103.
F. Knox, D. Kühn and D. Osthus, Edge-disjoint Hamilton cycles in random graphs, Random Structures Algorithms 46 (2015), 397–445.
M. Krivelevich, On the number of Hamilton cycles in pseudo-random graphs, Electron. J. Combin. 19 (2012), Paper 25, 14.
M. Krivelevich and W. Samotij, Optimal packings of Hamilton cycles in sparse random graphs, SIAM J. Discrete Math. 26 (2012), 964–982.
D. Kühn and D. Osthus, Hamilton decompositions of regular expanders: a proof of Kelly’s conjecture for large tournaments, Adv. Math. 237 (2013), 62–146.
D. Kühn and D. Osthus, Hamilton decompositions of regular expanders: applications, J. Combin. Theory Ser. B 104 (2014), 1–27.
L. Lovász, Combinatorial Problems and Exercises, second ed., Akadémiai Kiadó, Budapest, and North-Holland, Amsterdam, 1993.
C. McDiarmid, Clutter percolation and random graphs, Math. Programming Stud. (1980), 17–25, Combinatorial optimization, II (Proc. Conf., Univ. East Anglia, Norwich, 1979).
C. S. J. A. Nash-Williams, Hamiltonian lines in graphs whose vertices have sufficiently large valencies, in Combinatorial Theory and its Applications, III (Proc. Colloq., Balatonf üred, 1969), North-Holland, Amsterdam, 1970, pp. 813–819.
L. Pósa, Hamiltonian circuits in random graphs, Discrete Math. 14 (1976), 359–364.
G. N. Sárközy, S. M. Selkow and E. Szemerédi, On the number of Hamiltonian cycles in Dirac graphs, Discrete Math. 265 (2003), 237–250.
T. Szele, Kombinatorikai vizsgalatok az iranyitott teljes graffal kapcsolatban, Mat. Fiz. Lapok 50 (1943), 223–256.
C. Thomassen, Hamilton circuits in regular tournaments, in Cycles in graphs (Burnaby, B.C., 1982), North-Holland Math. Stud., Vol. 115, North-Holland, Amsterdam, 1985, pp. 159–162.
T. W. Tillson, A Hamiltonian decomposition of K*2m , 2m ≥ 8, J. Combin. Theory Ser. B 29 (1980), 68–74.
J. H. van Lint and R. M. Wilson, A course in combinatorics, second ed., Cambridge University Press, Cambridge, 2001.
E. M. Wright, For how many edges is a digraph almost certainly Hamiltonian?, Proc. Amer. Math. Soc. 41 (1973), 384–388.
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Ferber, A., Kronenberg, G. & Long, E. Packing, counting and covering Hamilton cycles in random directed graphs. Isr. J. Math. 220, 57–87 (2017). https://doi.org/10.1007/s11856-017-1518-7
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DOI: https://doi.org/10.1007/s11856-017-1518-7