A note on polynomial operator approximation

A note on polynomial approximation in Sobolev spaces

Résumé: Pour des domaines étoilés on donne des nouvelles bornes sur les constants dans les inégalités de Jackson pour les espaces de Sobolev. Pour des domaines convexes, les bornes ne dépendent pas de l’excentricité. Pour des domaines non-convexes ayant un point rentrant, les bornes sont uniformes par rapport à l’angle extérieur. L’outil central est un nouvel opérateur de projection sur l’espac...

A Note on the Degree of Polynomial Approximation*

Let C be a rectifiable Jordan curve of the finite z plane. We shall say that a function f(z) belongs to the class Lip (C, j , a) if ƒ (z) is regular in the limited region bounded by C (which we shall call the interior of C), if f{z) is continuous in the corresponding closed region, and if the jth. derivative of f(z) is also continuous in this closed region and satisfies a Lipschitz condition wi...

A note on inequalities for Tsallis relative operator entropy

‎In this short note‎, ‎we present some inequalities for relative operator entropy which are generalizations of some results obtained by Zou [Operator inequalities associated with Tsallis relative operator entropy‎, ‎{em Math‎. ‎Inequal‎. ‎Appl.}‎ ‎{18} (2015)‎, ‎no‎. ‎2‎, ‎401--406]‎. ‎Meanwhile‎, ‎we also show some new lower and upper bounds for relative operator entropy and Tsallis relative o...

A Note on Hilberts Operator

LEMMA L 1 When Kp< oo, then &fis a continuous (bounded) linear transformation with both domain and range Lp( — <*> , oo ), and § 2 / = — ƒ. LEMMA 2. Whenf(t)ÇzLi(— <*>, oo), then §ƒ exists for almost all x in ( — oo , co ), but does not necessarily belong to Li(a, b), where a, b are arbitrary numbers(— oo ^a<b^ oo) ; however (l+x)~\ &f\ÇzLi(— oo , co) when 0<q<l. When f and ^f belong to Li(— oo...

Note on a polynomial of