set with conditions, |F|≠1996
Source: Yugoslav TST 1996 P1
May 16, 2021
Setsnumber theorysetcombinatoricscombinatorics unsolved
Problem Statement
Let be a collection of subsets of the set satisfying the following conditions:(a) Any two distinct sets from have exactly one element in common;
(b) each element of is contained in exactly of the sets in .Can be equal to ?