Some things, like cubes, tetrahedrons, and Venn diagrams, seem so simple and natural that it’s kind of a surprise when you learn that their supply is very limited.

I know I’ve read somewhere about the challenge of Venn diagrams with 4 or more circles, but I can’t remember the place. It seems like a natural for John Cook but I couldn’t find it on his blog, so I’ll … Continue reading → …