A note on diameter-Ramsey sets

Corsten, J. & Frankl, N. (2018). A note on diameter-Ramsey sets. European Journal of Combinatorics, 71, 51-54. https://doi.org/10.1016/j.ejc.2018.02.036
Copy

A finite set A⊂Rd is called diameter-Ramsey if for every r∈N, there exists some n∈N and a finite set B⊂Rn with diam(A)=diam(B) such that whenever B is coloured with r colours, there is a monochromatic set A′⊂B which is congruent to A. We prove that sets of diameter 1 with circumradius larger than 1/2–√ are not diameter-Ramsey. In particular, we obtain that triangles with an angle larger than 135∘ are not diameter-Ramsey, improving a result of Frankl, Pach, Reiher and R\"odl. Furthermore, we deduce that there are simplices which are almost regular but not diameter-Ramsey.

picture_as_pdf

subject
Accepted Version

Download

Export as

EndNote BibTeX Reference Manager Refer Atom Dublin Core JSON Multiline CSV
Export