English

A note on $k$-wise oddtown problems

Combinatorics 2020-11-19 v1

Abstract

For integers 2tk2 \leq t \leq k, we consider a collection of kk set families Aj:1jk\mathcal{A}_j: 1 \leq j \leq k where Aj={Aj,i[n]:1im}\mathcal{A}_j = \{ A_{j,i} \subseteq [n] : 1 \leq i \leq m \} and A1,i1Ak,ik|A_{1, i_1} \cap \cdots \cap A_{k,i_k}| is even if and only if at least tt of the iji_j are distinct. In this paper, we prove that m=O(n1/k/2)m =O(n^{ 1/ \lfloor k/2 \rfloor}) when t=kt=k and m=O(n1/(t1))m = O( n^{1/(t-1)}) when 2t2k2t-2 \leq k and prove that both of these bounds are best possible. Specializing to the case where A=A1==Ak\mathcal{A} = \mathcal{A}_1 = \cdots = \mathcal{A}_k, we recover a variation of the classical oddtown problem.

Keywords

Cite

@article{arxiv.2011.09402,
  title  = {A note on $k$-wise oddtown problems},
  author = {Jason O'Neill and Jacques Verstraëte},
  journal= {arXiv preprint arXiv:2011.09402},
  year   = {2020}
}
R2 v1 2026-06-23T20:21:02.939Z