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  "body": "\n## Summary\n\nPost algebras are the algebras of Post's $n$-valued logic, in the same way as Boolean algebras are the algebras of classical two-valued logic.\nFor each $n \\ge 2$, the Post algebras of order $n$ form the variety generated by an $n$-element chain with a cyclic negation.\nThis generating algebra is [[primal|XD01Y7B6XW]], so Post algebras have a Boolean-like structure theory.\nFor $n = 2$ they are exactly the Boolean algebras.\n\n## Explanations\n\n### L1 human\n\nClassical logic has two truth values, and Boolean algebras capture its laws.\nEmil Post studied logics with $n$ truth values $0, 1, \\dots, n - 1$, ordered like a ladder, with a negation that moves every value one step up and the top value back to $0$.\nPost algebras collect all algebras that obey the same laws as this $n$-valued system.\nWith three values, for example, the negation sends $0 \\mapsto 1 \\mapsto 2 \\mapsto 0$.\n",
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