2016/02/24 by Day, A. Nicholas, Johnson, J. Robert · 3 citations
#Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.1602.07607
We show that for any positive integer r there exists an integer k and a k-colouring of the edges of K2k+1 with no monochromatic odd cycle of length less than r. This makes progress on a problem of Erdős and Graham and answers a question of Chung. We use these colourings to give new lower bounds on the k-colour Ramsey number of the odd cycle and prove that, for all odd r and all k sufficiently large, there exists a constant ε= ε(r) > 0 such that Rk(Cr) > (r-1)(2+ε)k-1.