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Markov- and Bernstein-Type Inequalities for Polynomials with Restricted Coefficients
Authors:Borwein  Peter  Erdélyi  Tamás
Abstract:The Markov-type inequality 
$$||p\prime ||_{0,1]} \leqslant cn\log (n + 1)||p||_{0,1]} $$
is proved for all polynomials of degree at most n with coefficients from {-1,0,1} with an absolute constant c. Here Verbar·Verbar0,1] denotes the supremum norm on 0,1]. The Bernstein-type inequality 
$$|p\prime (y)| \leqslant \frac{c} {{(1 - y)^2 }}||p||_{0,1]} ,y \in 0,1) $$
is shown for every polynomial p of the form 
$$p(x) = \sum\limits_{j = m}^n {a_j x^j } ,|a_m | = 1,|a_j | \leqslant 1,a_{j \in } \mathbb{C} $$
The inequality 
$$|p\prime (y)| \leqslant \frac{c} {{(1 - y)}}\log \left( {\frac{2} {{1 - y}}} \right)||p||_{0,1]} ,y \in 0,1) $$
is also proved for every analytic function p on the open unit disk D that satisfies the growth condition 
$$|p(0)| = 1,|p(z) \leqslant \frac{1} {{1 - |z|}},z \in D $$
Keywords:Markov  Bernstein  inequality  restricted coefficients  small integer coefficients  polynomial
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