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  "body": "\n## Summary\n\nA Venn diagram is a picture of the relations between a small number of sets.\nEach set is a closed curve, often a circle, inside a rectangle for the [[universal set|0BPYRMHJ48]].\nFor $n$ sets, the curves cut the plane into $2^n$ regions, one for each combination of \"in\" and \"out\" of the sets.\n\n## Remarks\n\nJohn Venn made these diagrams popular in the 1880s.\nThe diagrams make laws such as [[De Morgan's laws for sets|0VK0W4D5Y5]] visible, but a picture is not a proof.\nAn Euler diagram is similar, but it shows only the regions that are not empty.\n\n## Explanations\n\n### L1 human\n\nDraw two overlapping circles $A$ and $B$.\nThe overlap is $A \\cap B$, both circles together are $A \\cup B$, and the region outside both circles is the complement of $A \\cup B$.\n",
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