Cofinite Filter

If is an infinite set, then the collection $F_S={A subset= S:S-A is finite}$ is a filter called the cofinite (or Fréchet) filter on .

See also

Filter, Ultrafilter

This entry contributed by Viktor Bengtsson

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Bengtsson, Viktor. "Cofinite Filter." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/CofiniteFilter.html

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