Counting Circles and Other Things
Counting Circles and Other Things

Elena Fuchs, Princeton University
Fine Hall 214
Take a circle of radius one and inscribe in it two circles that are tangent to each other. Now add another circle into the original one so that it's tangent to all three. If we repeat this process over and over, we get an old picture known as the Apollonian circle packing. What radii will we get from one such packing? There are many ways to approach this simple question, and I'll tell you about some in this talk.