1. Department of Mathematics, University of Alabama, Box 870350, Tuscaloosa, AL 35487, USA
2. Department of Mathematics, Statistics and Computer Science, Macalester College, 1600 Grand Avenue, St Paul, MN 55105, USA
3. Department of Mathematics, University of California, South Hall, Room 6607, Santa Barbara, CA 93106, USA
4. Department of Mathematics, Oberlin College, 10 N. Professor St, King 205, Oberlin, OH 44074, USA
5. Department of Computer Science, University of Minnesota, 4-192 Keller Hall, 200 Union St SE, Minneapolis, MN 55455, USA
6. Department of Management Science and Engineering, Stanford University, Huang Engineering Center, 475 Via Ortega, Stanford, CA 94305, USA