scholarly journals New upper bound for multicolor Ramsey number of odd cycles

2019 ◽  
Vol 342 (1) ◽  
pp. 217-220 ◽  
Author(s):  
Qizhong Lin ◽  
Weiji Chen
2018 ◽  
Author(s):  
Benjamin Smith

We defined number of points with an inter-distance of β or more to necessarily exist on a plane. Furthermore, we aimed to reduce the range of this minimum value. We first showed that the upper bound of this value could be scaled by , and further reduced the constant that was multiplied. We compared the upper bound of and the Ramsey number in a special case and confirmed that was a better upper bound than except when were both small or trivial.


2013 ◽  
Vol 21 (3) ◽  
pp. 241-256 ◽  
Author(s):  
Manuel González Sarabia ◽  
Joel Nava Lara ◽  
Carlos Rentería Marquez ◽  
Eliseo Sarmíento Rosales

AbstractIn this paper we will compute the main parameters of the parameterized codes arising from cycles. In the case of odd cycles the corresponding codes are the evaluation codes associated to the projective torus and the results are well known. In the case of even cycles we will compute the length and the dimension of the corresponding codes and also we will find lower and upper bounds for the minimum distance of this kind of codes. In many cases our upper bound is sharper than the Singleton bound.


10.37236/257 ◽  
2009 ◽  
Vol 16 (1) ◽  
Author(s):  
Veselin Jungić ◽  
Tomáš Kaiser ◽  
Daniel Král'

We study the mixed Ramsey number $maxR(n,{K_m},{K_r})$, defined as the maximum number of colours in an edge-colouring of the complete graph $K_n$, such that $K_n$ has no monochromatic complete subgraph on $m$ vertices and no rainbow complete subgraph on $r$ vertices. Improving an upper bound of Axenovich and Iverson, we show that $maxR(n,{K_m},{K_4}) \leq n^{3/2}\sqrt{2m}$ for all $m\geq 3$. Further, we discuss a possible way to improve their lower bound on $maxR(n,{K_4},{K_4})$ based on incidence graphs of finite projective planes.


10.37236/2598 ◽  
2013 ◽  
Vol 20 (3) ◽  
Author(s):  
Tom Bohman ◽  
Ron Holzman ◽  
Venkatesh Natarajan

We give an upper bound on the independence number of the cube of the odd cycle $C_{8n+5}$. The best known lower bound is conjectured to be the truth; we prove the conjecture in the case $8n+5$ prime and, within $2$, for general $n$.


10.37236/1662 ◽  
2001 ◽  
Vol 9 (1) ◽  
Author(s):  
Benny Sudakov

The Ramsey number $r(C_l, K_n)$ is the smallest positive integer $m$ such that every graph of order $m$ contains either cycle of length $l$ or a set of $n$ independent vertices. In this short note we slightly improve the best known upper bound on $r(C_l, K_n)$ for odd $l$.


2016 ◽  
Vol 339 (12) ◽  
pp. 2857-2860 ◽  
Author(s):  
Kathleen Johst ◽  
Yury Person

2012 ◽  
Vol 71 (3) ◽  
pp. 293-316 ◽  
Author(s):  
Fabrıcio Siqueira Benevides
Keyword(s):  

10.37236/514 ◽  
2011 ◽  
Vol 18 (1) ◽  
Author(s):  
Yi Zhao

A conjecture of Loebl, also known as the $(n/2 - n/2 - n/2)$ Conjecture, states that if $G$ is an $n$-vertex graph in which at least $n/2$ of the vertices have degree at least $n/2$, then $G$ contains all trees with at most $n/2$ edges as subgraphs. Applying the Regularity Lemma, Ajtai, Komlós and Szemerédi proved an approximate version of this conjecture. We prove it exactly for sufficiently large $n$. This immediately gives a tight upper bound for the Ramsey number of trees, and partially confirms a conjecture of Burr and Erdős.


10.37236/9358 ◽  
2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Maria Axenovich ◽  
Izolda Gorgol

We write $F{\buildrel {\text{ind}} \over \longrightarrow}(H,G)$ for graphs $F, G,$ and $H$, if for any coloring of the edges of $F$ in red and blue, there is either a red induced copy of $H$ or a blue induced copy of $G$. For graphs $G$ and $H$, let $\mathrm{IR}(H,G)$ be the smallest number of vertices in a graph $F$ such that $F{\buildrel {\text{ind}} \over \longrightarrow}(H,G)$. In this note we consider the case when $G$ is a star on $n$ edges, for large $n$ and $H$ is a fixed graph. We prove that  $$ (\chi(H)-1) n \leq \mathrm{IR}(H, K_{1,n}) \leq (\chi(H)-1)^2n + \epsilon n,$$ for any $\epsilon>0$,  sufficiently large $n$, and $\chi(H)$ denoting the chromatic number of $H$. The lower bound is asymptotically tight  for any fixed bipartite $H$. The upper bound is attained up to a constant factor, for example when $H$ is a clique.


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