{
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  "body": "\n## Summary\n\nIn mathematics, the **Fréchet filter**, also called the **cofinite filter**, on a [[set|0BSJ7RQ9BW]] $X$ is a certain collection of subsets of $X$ (that is, it is a particular subset of the [[power set|00E0YZCERH]] of $X$). A subset $F$ of $X$ belongs to the Fréchet filter if and only if the [[complement|0RKF1ZT5JJ]] of $F$ in $X$ is finite. Any such set $F$ is said to be [[cofinite|1EZAT5BEVJ]] in $X$, which is why it is alternatively called the *cofinite filter* on $X$.\n",
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