For the plane curves Γ,the maximal operator associated to it is defined byMf(x)=sup|∫f(x-Γ(t))(r<sup>-1</sup>t)r<sup>-1</sup>dt|where is a Schwartz function.For
In this paper we give the exact order of丨x-x<sub>k</sub>丨<sup>丨</sup>l<sub>k</sub>(x)丨<sup>f</sup>or any fixed nonnegativeintegers s and t,which is n<sup>-s</
2-periodic trigonometric interpolation problems on 2n equidistant nodes and 4n+1 equi-distant nodes are considered respectively.Regularity theorems,fundamental