Totally agreed. Note that this is topologically equivalent to Branko Grunbaum's Venn diagram of 5 ellipses: https://commons.wikimedia.org/wiki/File:Symmetrical_5-set_Venn_diagram.svg Indeed, I suspect that Randall Munroe started with Grunbaum's Venn diagram and perturbed it to make the regions have roughly* equal area. * you could do this on the surface of a sphere, and get a 'Venn globe' where the antipodal involution x --> -x corresponds to complementation. -- APG.

Sent: Monday, March 11, 2019 at 5:18 PM From: rcs@xmission.com To: math-fun@mailman.xmission.com Cc: rcs@xmission.com Subject: [math-fun] Venn diagram

Today's XKCD has the best 5-variable Venn diagram drawing that I've seen. It's possible to draw VDs with any number of variables, but the diagrams are tortured, with the regions having odd shapes that make the visualization useless. It's even possible to make the single-variable regions convex, but the intersections are mostly sliver-shaped, and the dimensions vary widely. The XKCD layout is symmetric in each variable, and has reasonable size & shape for every region. There are lots of concavities, but they aren't awkward.

https://xkcd.com/2122/

Rich

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