A Ramsey Class for Steiner Systems
Combinatorics
2017-09-25 v3
Abstract
We construct a Ramsey class whose objects are Steiner systems. In contrast to the situation with general -uniform hypergraphs, it turns out that simply putting linear orders on their sets of vertices is not enough for this purpose: one also has to strengthen the notion of subobjects used from "induced subsystems" to something we call "strongly induced subsystems". Moreover we study the Ramsey properties of other classes of Steiner systems obtained from this class by either forgetting the order or by working with the usual notion of subsystems. This leads to a perhaps surprising induced Ramsey theorem in which designs get coloured.
Cite
@article{arxiv.1607.02792,
title = {A Ramsey Class for Steiner Systems},
author = {Vindya Bhat and Jaroslav Nešetřil and Christian Reiher and Vojtěch Rödl},
journal= {arXiv preprint arXiv:1607.02792},
year = {2017}
}
Comments
third version addresses changes arising from the referee reports