Main Page
|
See live article
|
Alphabetical index
G-delta set
In
topology
,
X
, a
G-delta set
(or
G
δ
set
) is a
countable
intersection
of open sets. In
metrizable
spaces, every
closed set
is a G
δ
set.
The complement of a G
δ
set is an
F
σ
. In a metrizable space, every open set is an F
σ
set.