MathDB
Hales–Jewett theorem

Source: Iran PPCE 2004

January 9, 2009
geometry3D geometrycombinatorics proposedcombinatorics

Problem Statement

Let l,d,k l,d,k be natural numbers. We want to prove that for large numbers n n, for each k k-coloring of the n n-dimensional cube with side length l l, there is a d d-dimensional subspace that all of its vertices have the same color. Let H(l,d,k) H(l,d,k) be the least number such that for nH(l,d,k) n\geq H(l,d,k) the previus statement holds. a) Prove that: H(l,d \plus{} 1,k)\leq H(l,1,k) \plus{} H(l,d,k^l)^{H(l,1,k)} b) Prove that H(l \plus{} 1,1,k \plus{} 1)\leq H(l,1 \plus{} H(l \plus{} 1,1,k),k \plus{} 1) c) Prove the statement of problem. d) Prove Van der Waerden's Theorem.