MathDB
TOT 002 1980 Spring J2 S2 delete a row in NxN array of numbers

Source:

August 16, 2019
combinatoricssquare tabletable

Problem Statement

In a N×NN \times N array of numbers, all rows are different (two rows are said to be different even if they differ only in one entry). Prove that there is a column which can be deleted in such a way that the resulting rows will still be different.
(A Andjans, Riga)