Baire category theorem: Difference between revisions

From Citizendium
Jump to navigation Jump to search
imported>Richard Pinch
(→‎References: page numbers)
imported>Richard Pinch
m (update link)
Line 1: Line 1:
In [[general topology]], the '''Baire category theorem''' states that a non-[[empty set|empty]] [[complete metric space]] is a [[second category space]]: that is, it is not a [[countability|countable]] [[union]] of [[nowhere dense set]]s (sets whose [[closure (mathematics)|closure]] have empty [[interior (topology)|interior]]).
In [[general topology]], the '''Baire category theorem''' states that a non-[[empty set|empty]] [[complete metric space]] is a [[second category space]]: that is, it is not a [[countability|countable]] [[union]] of [[nowhere dense set]]s (sets whose [[closure (topology)|closure]] have empty [[interior (topology)|interior]]).


==References==
==References==
* {{cite book | author=J.L. Kelley | authorlink=John L. Kelley | title=General topology | publisher=van Nostrand | year= 1955 | pages=200-201 }}
* {{cite book | author=J.L. Kelley | authorlink=John L. Kelley | title=General topology | publisher=van Nostrand | year= 1955 | pages=200-201 }}

Revision as of 15:31, 6 January 2009

In general topology, the Baire category theorem states that a non-empty complete metric space is a second category space: that is, it is not a countable union of nowhere dense sets (sets whose closure have empty interior).

References

  • J.L. Kelley (1955). General topology. van Nostrand, 200-201.