On Blaschke products associated with n-widths Original Research Article

Let E be a closed subset of the open unit disk G={z : |z|<1}, and let μ be a positive Borel measure with support supp μ=E. Denote by Ap the restriction on E of the closed unit ball of the Hardy space Hp(G), 1⩽p⩽∞. In this paper we investigate orthogonality properties of the extremal functions associated with the Kolmogorov, Gelfand, and linear n-widths of Ap in Lq(μ,E), 1⩽q<∞, q⩽p.