English

A construction of almost Steiner systems

Combinatorics 2013-03-19 v1

Abstract

Let nn, kk, and tt be integers satisfying n>k>t2n>k>t\ge2. A Steiner system with parameters tt, kk, and nn is a kk-uniform hypergraph on nn vertices in which every set of tt distinct vertices is contained in exactly one edge. An outstanding problem in Design Theory is to determine whether a nontrivial Steiner system exists for t6t\geq6. In this note we prove that for every k>t2k>t\ge2 and sufficiently large nn, there exists an almost Steiner system with parameters tt, kk, and nn; that is, there exists a kk-uniform hypergraph on nn vertices such that every set of tt distinct vertices is covered by either one or two edges.

Keywords

Cite

@article{arxiv.1303.4065,
  title  = {A construction of almost Steiner systems},
  author = {Asaf Ferber and Rani Hod and Michael Krivelevich and Benny Sudakov},
  journal= {arXiv preprint arXiv:1303.4065},
  year   = {2013}
}
R2 v1 2026-06-21T23:43:19.937Z