(a) Find the chromatic number of the unit sphere in n > 3 dimensional real Hilbert space.
(b) Find the chromatic number of the rational unit sphere in n > 3 dimensions.
(c) Find the minimum number of vectors in three dimensional real Hilbert space which orthogenerates a system of vectors whose chromatic number exceeds three. Generalize this result to n Dimensions.
(d) Find the minimum number of vectors in three dimensional real Hilbert space which orthogenerates a system of vectors for which no valuation (two-valued measure) exists such that every orthogonal tripod contains exactly two vectors whose measure is 0 and one vector whose measure is 1. Generalize this result to n Dimensions.