Definitions for

**"Closed set"**a set of uniqueness if and only if there exists a distribution S supported on the set (so in particular it must be singular) such that ( here are the Fourier coefficients)

The set complement of an open set in a topological space. I. e., a set of all points of the space not in some open set.

An area open only to those involved in the production of the image. Those usually allowed on set are the talent, photographer and photographer's assistant or director, cameraman and production people the director considers necessary for the scene.