NCTS(South)/ NCKU Math Colloquium
DATE	2012-03-15　16:10-17:00
PLACE	R204, 2F, NCTS, NCKU
SPEAKER	Dr. Li-Huei Liu 劉麗惠（Indiana University, USA）
TITLE	Real Analytic Metrics on S^2 with Total Absence of Finite Blocking
ABSTRACT	If (M,g) is a Riemannian manifold and (x,y) belongs to M*M, then a set P\{x,y} is said to be a blocking set for (x,y) if every geodesic from x to y passes through a point of P. If no pair (x,y) in M*M has a finite blocking set, then (M,g) is said to be totally insecure. We prove that there exist real analytic metrics h on S^2 such that each (S^2,h) is totally insecure.