Abstract:
N. N. Luzin has constructed a sieve defining a screened non-Borel analytic set and has indicated the arithmetical properties of points of this set. In this article it is shown that a screened analytic set contains continuum number of points which do not have these arithmetical properties. Necessary and sufficient arithmetical conditions on points are found, under which they lie in a Luzin set screened by a sieve.