On sharp constants in one-dimensional embedding theorems of arbitrary order
arXiv:1308.2259
Abstract
We discuss the problem where the extremal function in embedding theorem of some (generally speaking, non-integer) order is the constant function. We obtain the necessary and sufficient conditions of this.
Translation of the paper published in Russian in the collected volume "Problems of contemporary approximation theory", St.Petersburg Univ. Publishers, 2004, 146--158. Some comments are added