**Stephen G. Simpson
Department of Mathematics
Pennsylvania State University
**

**December 15, 1999**

The basic reference for reverse mathematics is my recently published
book *Subsystems of Second Order Arithmetic* [32]. The
web site for the book is `www.math.psu.edu/simpson/sosoa/`.
This article is a write-up of some representative open problems in
reverse mathematics. It was originally a handout for my 45-minute
invited talk at the AMS-INS-SIAM conference *Computability Theory
and Applications*, June 13-17, 1999, Boulder, Colorado.

- Contents
- Real Analysis and Topology
- Banach Space Theory
- Ramsey Theory
- WQO Theory
- Replacing by a Weaker Base Theory
- Bibliography
- About this document ...