Pointwise convergence along restricted directions for the fractional Schr\"odinger equation

Abstract

We consider the pointwise convergence problem for the solution of Schr\"odinger-type equations along directions determined by a given compact subset of the real line. This problem contains Carleson's problem as the most simple case and was studied in general by Cho--Lee--Vargas. We extend their result from the case of the classical Schr\"odinger equation to a class of equations which includes the fractional Schr\"odinger equations. To achieve this, we significantly simplify their proof by completely avoiding a time localization argument.