| DATE: | Thursday, December 13, 2001 |
| TIME: | 4:30-5:30 PM |
| PLACE: | LN 2205 |
| SPEAKER: | Stan Wagon (Macalester College) |
| TITLE: | A Computational View of the Four-Color Theorem: A Resuscitation of a Famous False Proof |
The Four-Color Theorem (proved in 1976) is one of the most famous theorems of mathematics. I will show how modern computation helps us understand the coloring of maps and graphs, using ideas stemming from the famous false proof of 1879 and also from a well-known hoax of April Fools Day, 1975. These ideas led to the resolution of a long-standing conjecture about coloring Penrose tilings. I will also discuss a recent result of D. Finn, showing how one can create a curved unicycle track that a bicycle can follow.