Dzyubenko, G.A.; Gilewicz, J.; Shevchuk, I.A.
(Український математичний журнал, 2002)
Assume that a function f ∈ C[−1, 1] changes its convexity at a finite collection Y := {y 1, ... y s} of s points yi ∈ (−1, 1). For each n > N(Y), we construct an algebraic polynomial Pn of degree ≤ n that is coconvex ...