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  "body": "\n## Summary\n\nA permutation pattern is a short [[permutation|05RWFKVTJ7]] that may occur inside a longer one, see the [[definition|DF69BF6841]].\nA permutation contains a pattern if some of its entries appear in the same relative order as the pattern, and avoids it otherwise.\nThe study of pattern avoidance counts the permutations that avoid given patterns.\nIts central result is the [[Stanley–Wilf conjecture|KWJS2QYJ1K]], now a theorem, which bounds these counts by an exponential.\n\n## Explanations\n\n### L1 human\n\nWrite a permutation as a row of numbers, such as $3\\,1\\,4\\,2$.\nPick some of the entries, keep their order, and look only at which is larger than which.\nPicking $3, 1, 2$ gives the shape \"high, low, middle\", which is the pattern $312$.\nThe row $3\\,1\\,4\\,2$ has no three entries that increase from left to right, so it avoids the pattern $123$.\n",
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