Furstenberg’s topological proof of the infinitude of primes

I just returned from a 10-day trip to India. It was my first visit there. I gave a talk at the ICM Satellite Conference: Various Aspects of Dynamical Systems. The conference was hosted by the Department of Mathematics at the M. S. University, Baroda, which is in Vadodara (formerly Baroda) in the Indian state of…

Nested nations

Recently I wrote about a neat land/water recursion that I found. I’ve seen countries that are completely surrounded by other countries (called enclaves)—Lesotho and San Marino being two examples. But I had no idea just how recursive this could become. Michael Tobis left a comment with a link to an eye-opening post on his Pining for Fjords…