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  "body": "\n## Summary\n\nEnumerative combinatorics is the part of [[combinatorics|0JKW7W7XFR]] that counts finite structures, see the [[definition|NWGARTY61Y]].\nIt asks for the number of objects of size $n$ in a family, as a function of $n$.\nIts answers take the form of closed formulas, [[recurrence relations|0FYX44GP92]], [[generating functions|0PHAC833JF]] or asymptotic estimates.\nIts tools range from bijections and the inclusion-exclusion principle to complex analysis in [[analytic combinatorics|YJK71RKVEB]].\n\n## Explanations\n\n### L1 human\n\nEnumerative combinatorics answers questions that begin with \"how many\".\nHow many ways are there to climb $n$ stairs taking one or two steps at a time?\nThe answer is a Fibonacci number, and a recurrence finds it: the last step is a single or a double step.\nThe aim is a formula or a fast method that works for every $n$ at once, not a list of cases.\n",
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