## Event Date:

## Event Location:

- 6635 South Hall

## Event Contact:

Guofang Wei

Email: wei@math.ucsb.edu

Abstract: A well-known result of J. P. Serre states that for an arbitrary pair of points on a closed Riemannian manifold there exist infinitely many geodesics connecting these points.

A natural question is whether one can estimate the length of the "k-th" geodesic in terms of the diameter of a manifold. We will demonstrate that given any pair of points p, q on a closed Riemannian manifold of dimension n and diameter d, there always exist at least k geodesics of length at most 4nk^2d connecting them.

We will also demonstrate that for any two points of a manifold that is diffeomorphic to the 2-sphere there always exist at least k geodesics between them of length at most 22kd. (Joint with A. Nabutovsky)