In this paper a particular solution of the problem of L. Flatto [1] has been given. Namely, the following theorem was proved. If there exists a point (a,b) S such that {a} x T c S, then for any function f C(T) there exists an optimal polynomial g O(f,Pk) such that g C(T).
From the text: "We generalize a theorem of G. Meinardus [Arch. Rational Mech. Anal. 14 (1963), 301–303; MR0156143] in two directions: first, instead of concrete function spaces we consider arbitrary normed spaces and secondly, we deal with the subspace of models-approximating elements-that can be of arbitrary measure. The operator in regard to which we study the invariability of the approximation is linear.''
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