Is the Union-closed sets conjecture the best possible?
J-C. Renaud · Journal of the Australian Mathematical Society Series A Pure Mathematics and Statistics · 1991
Abstract A slightly strengthened version of the union-closed sets conjecture is proposed. It is shown that this version holds for a minimum set size of one or two and an examination of a boundary function shows that it holds for collections containing up to 19 sets. Some related conjectures are outlined.