# G-delta

From Encyclopedia of Mathematics

2020 Mathematics Subject Classification: *Primary:* 28A05 [MSN][ZBL]

In a topological space $X$ a subset which is the countable intersection of open sets. See Borel set and also F-sigma.

**How to Cite This Entry:**

G-delta.

*Encyclopedia of Mathematics.*URL: http://encyclopediaofmath.org/index.php?title=G-delta&oldid=27667