On the riesz means of expansion by riesz bases formed by eigen functions for the ordinary differential operator of 2m-th order

الملخص EN

The aim of this paper is to prove a theorem on the Riesz means of expansions with respect to Riesz bases, which extends the previous results of [1] and [2] on the Schrödinger operator and the ordinary differential operator of 4-th order to the operator of order 2m by using the eigen functions of the ordinary differential operator.

Some Symbols that used in the paper : || || the uniform norm.

<, > the inner product in L2.

∂G the set of all boundary elements of G.

û the dual function of u.