MathDB

Arrays

Source: INMO 1996 Problem 6

October 6, 2005

linear algebramatrixcombinatorics unsolvedcombinatorics

Problem Statement

There is a

2n \times 2n

array (matrix) consisting of

0's

and

1's

and there are exactly

3n

zeroes. Show that it is possible to remove all the zeroes by deleting some

n

rows and some

n

columns.