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  "body": "\n## Summary\n\nThe Parry measure is a special shift-[[invariant measure|B232EZ1FMB]] on an irreducible [[subshift of finite type|624XDXX8FN]].\nIt is the unique invariant probability measure of maximal entropy.\nSo its [[Kolmogorov–Sinai entropy|X1D1C7VH6P]] equals the [[topological entropy|BDZYBXBFDE]] $\\log \\lambda$, where $\\lambda$ is the Perron eigenvalue of the transition matrix.\nIt is a Markov measure built from the left and right Perron eigenvectors.\nIt shows the [[variational principle for entropy|HHR8HP3R6G]] at work in the simplest case.\n\n## Explanations\n\n### L1 human\n\nA subshift of finite type allows some words and forbids others.\nAmong all ways to pick an allowed sequence at random, the Parry measure is the one that is as unpredictable as possible.\nIt does not give each symbol equal weight; it weights them by how many long allowed words pass through them.\nFor the golden mean shift, where $11$ is forbidden, it gives the symbol $0$ probability $\\varphi^2/(\\varphi^2 + 1)$, with $\\varphi$ the golden ratio.\nSee the [[definition|BE3E2AH0EV]].\n",
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