English

On quantitative aspects of a canonisation theorem for edge-orderings

Combinatorics 2022-11-15 v2

Abstract

For integers k2k\ge 2 and N2k+1N\ge 2k+1 there are k!2kk!2^k canonical orderings of the edges of the complete kk-uniform hypergraph with vertex set [N]={1,2,,N}[N] = \{1,2,\dots, N\}. These are exactly the orderings with the property that any two subsets A,B[N]A, B\subseteq [N] of the same size induce isomorphic suborderings. We study the associated canonisation problem to estimate, given kk and nn, the least integer NN such that no matter how the kk-subsets of [N][N] are ordered there always exists an nn-element set X[N]X\subseteq [N] whose kk-subsets are ordered canonically. For fixed kk we prove lower and upper bounds on these numbers that are kk times iterated exponential in a polynomial of nn.

Keywords

Cite

@article{arxiv.2012.09256,
  title  = {On quantitative aspects of a canonisation theorem for edge-orderings},
  author = {Christian Reiher and Vojtěch Rödl and Marcelo Sales and Kevin Sames and Mathias Schacht},
  journal= {arXiv preprint arXiv:2012.09256},
  year   = {2022}
}

Comments

revised according to referee report