scholarly journals Color Isomorphic Even Cycles and a Related Ramsey Problem

2020 ◽  
Vol 34 (3) ◽  
pp. 1999-2008
Author(s):  
Gennian Ge ◽  
Yifan Jing ◽  
Zixiang Xu ◽  
Tao Zhang
Keyword(s):  
2018 ◽  
Vol 16 (2) ◽  
pp. 437-441 ◽  
Author(s):  
Chula Jayawardene ◽  
Keyword(s):  

2020 ◽  
Vol 29 (6) ◽  
pp. 830-867 ◽  
Author(s):  
Shagnik Das ◽  
Andrew Treglown

AbstractGiven graphs H1, H2, a graph G is (H1, H2) -Ramsey if, for every colouring of the edges of G with red and blue, there is a red copy of H1 or a blue copy of H2. In this paper we investigate Ramsey questions in the setting of randomly perturbed graphs. This is a random graph model introduced by Bohman, Frieze and Martin [8] in which one starts with a dense graph and then adds a given number of random edges to it. The study of Ramsey properties of randomly perturbed graphs was initiated by Krivelevich, Sudakov and Tetali [30] in 2006; they determined how many random edges must be added to a dense graph to ensure the resulting graph is with high probability (K3, Kt) -Ramsey (for t ≽ 3). They also raised the question of generalizing this result to pairs of graphs other than (K3, Kt). We make significant progress on this question, giving a precise solution in the case when H1 = Ks and H2 = Kt where s, t ≽ 5. Although we again show that one requires polynomially fewer edges than in the purely random graph, our result shows that the problem in this case is quite different to the (K3, Kt) -Ramsey question. Moreover, we give bounds for the corresponding (K4, Kt) -Ramsey question; together with a construction of Powierski [37] this resolves the (K4, K4) -Ramsey problem.We also give a precise solution to the analogous question in the case when both H1 = Cs and H2 = Ct are cycles. Additionally we consider the corresponding multicolour problem. Our final result gives another generalization of the Krivelevich, Sudakov and Tetali [30] result. Specifically, we determine how many random edges must be added to a dense graph to ensure the resulting graph is with high probability (Cs, Kt) -Ramsey (for odd s ≽ 5 and t ≽ 4).To prove our results we combine a mixture of approaches, employing the container method, the regularity method as well as dependent random choice, and apply robust extensions of recent asymmetric random Ramsey results.


2020 ◽  
Vol 94 (4) ◽  
pp. 509-517
Author(s):  
Luka Milićević
Keyword(s):  

2020 ◽  
Vol 22 (4) ◽  
pp. 1247-1259 ◽  
Author(s):  
Dhruv Mubayi ◽  
Andrew Suk
Keyword(s):  

COMBINATORICA ◽  
1997 ◽  
Vol 17 (4) ◽  
pp. 459-467 ◽  
Author(s):  
Paul Erdős ◽  
András Gyárfás
Keyword(s):  

1987 ◽  
Vol 67 (3) ◽  
pp. 227-233 ◽  
Author(s):  
P Erdös ◽  
R.J Faudree ◽  
C.C Rousseau ◽  
R.H Schelp
Keyword(s):  

1999 ◽  
Vol 22 (1) ◽  
pp. 48-59 ◽  
Author(s):  
W.A Carnielli ◽  
E.L Monte Carmelo

1983 ◽  
Vol 7 (1) ◽  
pp. 137-147 ◽  
Author(s):  
Paul Erdös ◽  
János Pach
Keyword(s):  

2017 ◽  
Vol 23 (07) ◽  
pp. 2649-2674
Author(s):  
Shen Guo ◽  
Zheng Jiang

This paper examines China's optimal fiscal policy in a general equilibrium model, in which the government finances its budget through both a special instrument, an implicit tax on the residential land, and a typical conventional instrument, the value-added tax (VAT). By solving a Ramsey problem, we find that (i) the optimal policy suggests a much lower land tax rate than the existing rate in China, and (ii) a substantial part of debt stabilization should come through an adjustment in the VAT rate, instead of relying on land financing. Switching from the existing policy to the Ramsey policy generates significant welfare gains.


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