noun A Banach space (X,‖⋅‖), such that, given a sequence of independent random variables from a Rademacher distribution, (εi), and a rank q in the range from 2 to infinity, there exists a finite constant C≥1 such that for all finite sequences (xi)∈X, 𝔼ε[‖∑i=1nεixi‖q]≥1Cq(∑i=1n‖xi‖q),if2≤q<∞ or 𝔼ε[‖∑i=1nεixi‖]≥1Csup‖xi‖,ifq=∞ .