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  "body": "\n## Summary\n\nA stationary set in a regular uncountable cardinal $\\kappa$ is a subset of $\\kappa$ that meets every [[club set|YW8YSCFPG5]].\nIf club sets are the \"almost all\" sets, stationary sets are the sets that are \"not negligible\".\nThey are central in combinatorial set theory, through [[Fodor's lemma|55W1M20Q3F]], the [[diamond principle|HFQSSB1Z23]] and forcing axioms; the [[precise definition|6FDYJVG1CK]] is given separately.\n\n## Explanations\n\n### L1 human\n\nAmong the countable ordinals, the club sets are those that are \"almost everything\".\nA stationary set is one that you cannot avoid with a club set: whichever club set you pick, the two share a point.\nEvery club set is stationary.\nOne level up, the set of all ordinals of cofinality $\\omega$ below $\\omega_2$ is stationary in $\\omega_2$.\nA bounded set, for instance all ordinals below $\\omega \\cdot 2$, is not stationary in $\\omega_1$, because the ordinals above it form a club set that misses it.\n",
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