regular G_δ set

Definition

A subset H of a space X is called a regular G_δ set if H is an intersection of a sequence of closed sets whose interiors contain H. The complement of a regular G_δset is called a regular F_σ set.

Reference

J. K. Hohli and D. Singh, Between compactness and quasicompactness, Acta. Math. Hungar. 106 (4) (2005), 317-329.