# Sums of square roots

Why has it taken me so long to figure out that Richard Lipton has a blog? Anyway he has a great recent post, starting out as a reminiscence about how theory talks used to be given and segueing into the still open and still very interesting question of how to compare the lengths of two polygonal chains exactly and efficiently. For some more geometric computing flavor, he also has another recent post on Rabin's randomized linear time algorithm for finding closest pairs.