Setwise intersecting families of permutations
Abstract
A family of permutations is said to be \emph{-set-intersecting} if for any two permutations , there exists a -set whose image is the same under both permutations, i.e. . We prove that if is sufficiently large depending on , the largest -set-intersecting families of permutations in are cosets of stabilizers of -sets. The case of this was conjectured by J\'anos K\"orner. It can be seen as a variant of the Deza-Frankl conjecture, proved in [4]. Our proof uses similar techniques to those of [4], namely, eigenvalue methods, together with the representation theory of the symmetric group, but the combinatorial part of the proof is harder.
Cite
@article{arxiv.1106.0725,
title = {Setwise intersecting families of permutations},
author = {David Ellis},
journal= {arXiv preprint arXiv:1106.0725},
year = {2019}
}
Comments
'Erratum' section added. Yuval Filmus has recently pointed out that Theorem 26 (which was used in the proof of Theorem 25, regarding the case of equality), is false for $t > 1$, so an alternative proof of Theorem 25 has been sketched