| Institution: | (1) Department of Mathematics, Columbia University, New York, NY 10027, USA (e-mail: {lborisov, psorin}@math.columbia.edu, http://www.math.columbia.edu/˜borisov , http://www.math.columbia.edu/˜psorin), US;(2) Department of Mathematics and Computer Science, Rutgers University, Newark, NJ 07102–1811, USA (e-mail: gunnells@andromeda.rutgers.edu), US;(3) State University of New York at Stony Brook, Stony Brook, NY 11794-3651, USA (e-mail: sorin@math.sunysb.edu, http://www.math.sunysb.edu/˜orin/), US |
