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Turkey NMO 2001 Problem 6, Coloring Problem

Source: Turkey NMO 2001 Problem 6

September 30, 2011
combinatorics unsolvedcombinatorics

Problem Statement

We wish to color the cells of a n×nn \times n chessboard with kk different colors such that for every i{1,2,...,n}i\in \{1,2,...,n\}, the 2n12n-1 cells on ii. row and ii. column have all different colors.
a) Prove that for n=2001n=2001 and k=4001k=4001, such coloring is not possible.
b) Show that for n=2m1n=2^{m}-1 and k=2m+11k=2^{m+1}-1, such coloring is possible.