Zeev Ditzian

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For trigonometric polynomials on [−, ] ≡ T , the classical Jackson inequality E n (f) p C r (f, 1/n) p was sharpened by M. Timan for 1 < p < ∞ to yield n −r n k=1 k sr−1 E k (f) s p 1/s C r (f, n −1) p where s = max(p, 2). In this paper a general result on the relations between systems or sequences of best approximation and appropriate measures of(More)