A n x 6 - array
Source: Baltic Way 2005/7
November 7, 2005
vectorfloor functioncombinatorics proposedcombinatoricsBaltic Way2005#7
Problem Statement
A rectangular array has rows and columns, where . In each cell there is written either or . All rows in the array are different from each other. For each two rows and , the row can be found in the array as well. Prove that there is a column in which at least half of the entries are zeros.