MathDB
Select a separating family

Source: Miklós Schweitzer 2014, problem 1

December 23, 2014
ceiling functionlogarithmscombinatorics unsolvedcombinatorics

Problem Statement

Let nn be a positive integer. Let F\mathcal{F} be a family of sets that contains more than half of all subsets of an nn-element set XX. Prove that from F\mathcal{F} we can select log2n+1\lceil \log_2 n \rceil + 1 sets that form a separating family on XX, i.e., for any two distinct elements of XX there is a selected set containing exactly one of the two elements.
Moderator says: http://www.artofproblemsolving.com/Forum/viewtopic.php?f=41&t=614827&hilit=Schweitzer+2014+separating