نتایج جستجو برای: ramsey number

تعداد نتایج: 1171359  

Journal: :Discrete Mathematics 1997

Journal: :The Electronic Journal of Combinatorics 2011

Journal: :Trends in mathematics 2021

A 4-uniform tight cycle is a hypergraph with cyclic ordering of its vertices such that edges are precisely the sets 4 consecutive in ordering. We prove Ramsey number for on 4n \((5 +o(1))n\). This asymptotically tight.

2011
GYULA KÁROLYI VERA ROSTA V. ROSTA

The Ramsey multiplicity R(G) of a graph G is the minimum number of monochromatic copies of G in any two-colouring of the edges of Kr(G), where r(G) denotes the Ramsey number of G. Here we prove that odd cycles have super-exponentially large Ramsey multiplicity: If Cn is an odd cycle of length n, then logR(Cn) = Θ(n logn).

2006
KASHIF ALI SURAHMAT Kashif Ali Surahmat

A graph is Ramsey unsaturated if there exists a proper supergraph of the same order with the same Ramsey number, and Ramsey saturated otherwise. We present some result concerning both Ramsey saturated and unsaturated graph. In particular, we show that a cycle Cn and a Jahangir Jm Ramsey unsaturated or saturated graphs of R(Cn,Wm) and R(Pn, Jm), respectively. We also suggest an open problems.

Journal: :Journal of Graph Theory 2006
Paul N. Balister Jenö Lehel Richard H. Schelp

A graph is Ramsey unsaturated if there exists a proper supergraph of the same order with the same Ramsey number, and Ramsey saturated otherwise. We present some conjectures and results concerning both Ramsey saturated and unsaturated graphs. In particular, we show that cycles Cn and paths Pn on n vertices are Ramsey unsaturated for all n ≥ 5. 1 Results and Conjectures Throughout this article, r...

Journal: :Electronic Notes in Discrete Mathematics 2015
Martin Balko Josef Cibulka Karel Král Jan Kyncl

An ordered graph G< is a graph G with vertices ordered by the linear ordering <. The ordered Ramsey number R(G<, c) is the minimum number N such that every ordered complete graph with c-colored edges and at least N vertices contains a monochromatic copy of G<. For unordered graphs it is known that Ramsey numbers of graphs with degrees bounded by a constant are linear with respect to the number ...

Journal: :Combinatorics, Probability & Computing 2014
Jozef Skokan Maya Jakobine Stein

We call a graph H Ramsey-unsaturated if there is an edge in the complement of H such that the Ramsey number r(H) of H does not change upon adding it to H. This notion was introduced by Balister, Lehel and Schelp in [2], where it is shown that cycles (except for C4) are Ramsey-unsaturated, and conjectured that, moreover, one may add any chord without changing the Ramsey number of the cycle Cn, u...

Journal: :Graphs and Combinatorics 2008
Brendan Nagle Sayaka Olsen Vojtech Rödl Mathias Schacht

We consider a hypergraph generalization of a conjecture of Burr and Erdős concerning the Ramsey number of graphs with bounded degree. It was shown by Chvátal, Rödl, Trotter, and Szemerédi [The Ramsey number of a graph with bounded maximum degree, J. Combin. Theory Ser. B 34 (1983), no. 3, 239–243] that the Ramsey number R(G) of a graph G of bounded maximum degree is linear in |V (G)|. We derive...

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