Gδ set

A Gδ set is a set which can be expressed as the intersectionMathworldPlanetmath of a countableMathworldPlanetmath collectionMathworldPlanetmath of open sets.

The complement of a Gδ set is an Fσ set (http://planetmath.org/F_sigmaSet).

For example, the closed intervalMathworldPlanetmath [-1,+1] is a Gδ set because

Title Gδ set
Canonical name GdeltaSet
Date of creation 2013-03-22 14:38:02
Last modified on 2013-03-22 14:38:02
Owner rspuzio (6075)
Last modified by rspuzio (6075)
Numerical id 7
Author rspuzio (6075)
Entry type Definition
Classification msc 54A05
Related topic F_sigmaSet
Related topic PavedSet
Related topic PavedSpace