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Frechet filter
In mathematics, Fréchet filter is an important concept in order theory.
If X is an infinite set, the Fréchet filter, also called cofinite filter on X, is the set of all subsets of X having finite complement in X.
For example, on the set N of natural numbers, the set
B = { (n,∞) ; n
N}
is a Fréchet filter base, i.e. the Fréchet filter on N consists of all supersets of elements of B.
See also
Last updated: 10-14-2005 18:37:24
10-26-2009 08:16:03
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details