Public or Private: Public

The Famous 4-color Theorem states that four colors are sufficient to color any map on a plane or sphere so that regions sharing a boundary line are different colors. The less well-known Map Coloring Theorem gives a formula for the number of colors needed for a map drawn on a torus with one or more holes. Visualizing such maps is quite difficult. Over the past several years I have been trying to understand maps on these surfaces by constructing models in various media. I have published directions for these models so you can learn how to make your own!

Eve Torrence is professor emeritus at Randolph-Macon College where she taught from 1994 to 2021. She is the author of Cut and Assemble Icosahedra: Twelve models in White and Color and co-author with her husband and fellow mathematician, Bruce Torrence, of The Student’s Introduction to Mathematica. She has served as the chair of the Maryland-DC-Virginia Section of the MAA and President of Pi Mu Epsilon Mathematics Honor Society. Eve is currently a member of the Bridges Organization Board and has served as a Proceedings editor for six Bridges conferences.