English

The 3-way intersection problem for S(2, 4, v) designs

Combinatorics 2013-01-22 v1

Abstract

In this paper the 3-way intersection problem for S(2,4,v)S(2,4,v) designs is investigated. Let bv=v(v1)12b_{v}=\frac {v(v-1)}{12} and I3[v]={0,1,...,bv}{bv7,bv6,bv5,bv4,bv3,bv2,bv1}I_{3}[v]=\{0,1,...,b_{v}\}\setminus\{b_{v}-7,b_{v}-6,b_{v}-5,b_{v}-4,b_{v}-3,b_{v}-2,b_{v}-1\}. Let J3[v]={kJ_{3}[v]=\{k| there exist three S(2,4,v)S(2,4,v) designs with kk same common blocks}\}. We show that J3[v]I3[v]J_{3}[v]\subseteq I_{3}[v] for any positive integer v1,4 (mod 12)v\equiv1, 4\ (\rm mod \ 12) and J3[v]=I3[v]J_{3}[v]=I_{3}[v], for v49 v\geq49 and v=13v=13 . We find J3[16]J_{3}[16] completely. Also we determine some values of J3[v]J_{3}[v] for  v=25,28,37\ v=25,28,37 and 40.

Cite

@article{arxiv.1301.4764,
  title  = {The 3-way intersection problem for S(2, 4, v) designs},
  author = {Saeedeh Rashidi and Nasrin Soltankhah},
  journal= {arXiv preprint arXiv:1301.4764},
  year   = {2013}
}

Comments

accepted in Utilitas mathematics

R2 v1 2026-06-21T23:12:37.133Z