Table of Contents
Featured Articles and Invitations from the AMS
Interview with Mikio Sato
Emmanuel Andronikof
The late Emmanuel Andronikof talked to the distinguished mathematician about his work and life.
The Four Vertex Theorem and Its Converse
Dennis DeTurck, Herman Gluck, Daniel Pomerleano, and David Shea Vick
The Four Vertex Theorem of global differential geometry says that the curvature of a simple closed plane curve, if not constant, has at least four local extrema. The converse asserts that any continuous real-valued function on the circle with at least two local maxima and two local minima is the curvature function of a simple closed curve. The authors explain the proof of both.