A set is called a G delta set if it can be written as the countableintersection of open sets. Any closed set is a G delta set. The complement of a G delta set is called a F sigma set[?]. It is easy to see that any open set is a F sigma set.
All Wikipedia text
is available under the
terms of the GNU Free Documentation License
Search Encyclopedia
Search over one million articles, find something about almost anything!
... Museum[?]
Ipswich Museum[?]
Sue Ryder Foundation Museum[?], Cavendish
William Clowes Printing Museum[?], Beccles
West Sussex
Amberley Working Museum, ...