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  "body": "\n## Summary\n\nA Sheffer function on a finite set $A$ is a single operation on $A$ that is [[functionally complete|TDZVCWYJ9F]] by itself.\nEvery operation on $A$ can then be written as a composition of copies of it.\nOn $\\set{0, 1}$ the binary Sheffer functions are NAND and NOR.\nSheffer functions show that one well-chosen operation can carry the whole expressive power of a many-valued logic.\n\n## Explanations\n\n### L1 human\n\nThe NAND gate outputs $0$ only when both inputs are $1$.\nChips can be built from NAND gates alone, because NAND can imitate every other gate.\nFor example, $\\neg x$ is $x \\uparrow x$, and $x \\wedge y$ is $(x \\uparrow y) \\uparrow (x \\uparrow y)$.\nAn operation with this \"one gate does everything\" property is called a Sheffer function.\n",
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