On Best Polynomial Approximations in L2
For the τ-moduli of smoothness of mth order, we calculate exact constants in Jackson-type inequalities. We also obtain the exact values of the n-widths of classes of functions whose rth derivatives are characterized by τ-moduli of smoothness majorized by functions satisfying certain constraints. We present an example of the majorant for which all the stated requirements are satisfied.
In this work, we study the existence and multiplicity of positive solutions for the higher order p-Laplacian boundary value problem with even derivatives