A probabilistic approach to the geometry of the ℓᵨⁿ-ball

This article investigates, by probabilistic methods, various geometric questions on B n p , the unit ball of ln p . We propose realizations in terms of independent random variables of several distributions on B n p , including the normalized volume measure. These representations allow us to unify and extend the known results of the sub-independence of coordinate slabs in B n p . As another application, we compute moments of linear functionals on B n p , which gives sharp constants in Khinchine's inequalities on B n p and determines the 2-constant of all directions on B n p . We also study the extremal values of several Gaussian averages on sections of B n p (including mean width and l-norm), and derive several monotonicity results as p varies. Applications to balancing vectors in l 2 and to covering numbers of polyhedra complete the exposition.