On the n−th linear polarization constant of Rn

Abstract

Abstract. We prove that given any set of n unit vectors {vi}n i=1 ⊂ Rn, the inequality sup kxkRn=1 |hx, v1i · · · hx, vni| ≥ n−n/2 holds for n ≤ 14. Moreover, the equality is attained if and only if {vi}n i=1 is an orthonormal system.