Characterizing the amoeba

Kevin Purbhoo
Mathematics Department, University of British Columbia

Abstract: An amoeba is the set of all points (log|z_1|, ... log|z_n|), where (z_1, ... ,z_n) are the solutions to a system of polynomial equations. The name comes from the fact that pictures of these sets have a tendency to look like single celled organisms. Amoebas haved proved to be important in a number of different parts of math, including a recent partial solution to a Hilbert problem. Yet the most basic question, "given a point in R^n, how can one tell if it's in the amoeba" is non-trivial. The simplest case of this problem is: given a single polynomial f(z) in one variable, determine whether it has a root on the unit circle. I will talk about an approach to this problem, based on the triangle inequality, which turns out to generalise nicely to the case of systems of polynomials in several variables.