A sharp threshold for random graphs with a monochromatic triangle in every edge coloring

Let R be the set of all finite graphs G with the Ramsey property that every coloring of the edges of G by two colors yields a monochromatic triangle. In this paper we establish a sharp threshold for random graphs with this property. Let G(n,p) be the random graph on n vertices with edge probability p. We prove that there exists a function b =b(n) = �(1) such that for any " > 0, as n tends to infinity,

[1]  Béla Bollobás,et al.  Random Graphs , 1985 .

[2]  S. Janson,et al.  Upper tails for subgraph counts in random graphs , 2004 .

[3]  Vojtech Rödl,et al.  Random Graphs with Monochromatic Triangles in Every Edge Coloring , 1994, Random Struct. Algorithms.

[4]  Vojtech Rödl,et al.  On Schur Properties of Random Subsets of Integers , 1996 .

[5]  Vojtech Rödl,et al.  Large triangle-free subgraphs in graphs withoutK4 , 1986, Graphs Comb..

[6]  D. Achlioptas,et al.  A sharp threshold for k-colorability , 1999 .

[7]  Michael Krivelevich,et al.  Sharp thresholds for certain Ramsey properties of random graphs , 2000, Random Struct. Algorithms.

[8]  B. Rothschild,et al.  Every graph is contained in a sparsest possible balanced graph , 1985, Mathematical Proceedings of the Cambridge Philosophical Society.

[9]  P. Erdos,et al.  On the evolution of random graphs , 1984 .

[10]  Yoshiharu Kohayakawa,et al.  Szemerédi’s Regularity Lemma and Quasi-randomness , 2003 .

[11]  Tomasz Luczak On triangle-free random graphs , 2000, Random Struct. Algorithms.

[12]  Vojtech Rödl,et al.  A Fast Approximation Algorithm for Computing the Frequencies of Subgraphs in a Given Graph , 1995, SIAM J. Comput..

[13]  Tomasz Łuczak,et al.  On triangle-free random graphs , 2000 .

[14]  Vojtech Rödl,et al.  Extremal problems on set systems , 2002, Random Struct. Algorithms.

[15]  Andrzej Rucinski,et al.  Ramsey properties of random graphs , 1992, J. Comb. Theory, Ser. B.

[16]  B. Bollobás The evolution of random graphs , 1984 .

[17]  Béla Bollobás,et al.  Threshold functions , 1987, Comb..

[18]  Ehud Friedgut,et al.  A Sharp Threshold for k-Colorability , 1999, Random Struct. Algorithms.

[19]  Vojtech Rödl,et al.  The Algorithmic Aspects of the Regularity Lemma , 1994, J. Algorithms.

[20]  V. Rödl,et al.  Threshold functions for Ramsey properties , 1995 .

[21]  Andrzej Rucinski,et al.  Two variants of the size Ramsey number , 2005, Discuss. Math. Graph Theory.

[22]  Andrzej Ruciński,et al.  Rado Partition Theorem for Random Subsets of Integers , 1997 .

[23]  V. Rödl,et al.  Arithmetic progressions of length three in subsets of a random set , 1996 .

[24]  Yoshiharu Kohayakawa,et al.  Regular pairs in sparse random graphs I , 2003, Random Struct. Algorithms.

[25]  Vojtech Rödl,et al.  Ramsey Properties of Random Hypergraphs , 1998, J. Comb. Theory, Ser. A.

[26]  Y. Kohayakawa Szemerédi's regularity lemma for sparse graphs , 1997 .

[27]  S. Ross A random graph , 1981 .

[28]  M. Simonovits,et al.  Szemeredi''s Regularity Lemma and its applications in graph theory , 1995 .

[29]  Alan M. Frieze,et al.  Random graphs , 2006, SODA '06.

[30]  Yoshiharu Kohayakawa,et al.  Ramsey Games Against a One-Armed Bandit , 2003, Comb. Probab. Comput..

[31]  E. Friedgut,et al.  Sharp thresholds of graph properties, and the -sat problem , 1999 .

[32]  Michael Krivelevich,et al.  Sharp Thresholds for Ramsey Properties of Random Graphs , 1999 .

[33]  Svante Janson,et al.  Random graphs , 2000, ZOR Methods Model. Oper. Res..

[34]  Vojtech Rödl,et al.  Regularity properties for triple systems , 2003, Random Struct. Algorithms.