*Visual Insight*is a place to share striking images that help explain advanced topics in mathematics. I'm always looking for truly beautiful images, so if you know about one, please tell me! I can take jpg, png or gif files, but not videos such as YouTube videos, since that won't work well on the AMS homepage. If you have created an image that you want to share, please include a link to it a comment here, or email me the image at

baez@math.removethis.ucr.andthis.edu

Correctly using this email address involves a slight intelligence test.
If I choose your image, I'll need to know your email address so I can send you a partially filled out permission form for you to grant the American Mathematical Society the right to use your image here. You need to have the rights to the image to do this. Don't be scared: filling out this form won't prevent you from doing whatever *you*want with your image! New posts will show up on the 1st and 15th of each month.

*Visual Insight*is one of a series of blogs offered by the American Mathematical Society.

Here is a very handy tool for jpg to png image conversion http://jpgtopng.com/. Try it out, it is fast, free and easy to use.

Hi John. You can find a visual construction of a solution to Kirkman’s fifteen schoolgirl problem in the paper

“Kirkman’s Tetrahedron and the Fifteen Schoolgirl Problem”, The American Mathematical Monthly, 118:10, 887-900.

See

https://www.tandfonline.com/doi/abs/10.4169/amer.math.monthly.118.10.887

or

https://www.tandfonline.com/doi/pdf/10.4169/amer.math.monthly.118.10.887?needAccess=true

Best regards,

Marco

Cool, thanks!

Hi,

do the mathematics of simple graphs and equivalence classes fall into the category of advanced topics in mathematics? I am guessing maybe so here is a link to “About Fifty”

http://gallery.bridgesmathart.org/exhibitions/2020-joint-mathematics-meetings/edvogel56

Thanks for having a look. I enjoy your math tweets.

I’d say equivalence classes are things all math majors should learn about as undergrads, while simple graphs are something they’d learn about if they were interested in discrete math.

Why does the AMS list this Blog as “retired”? Is it restricted to retired mathematicians?

No, it’s because I’ve stopped posting new articles. Perhaps when I retire I’ll start writing them again.