Joel Louwsma is an undergraduate mathematics major at the University of Michigan. In July 2004 he participated in an REU at UNICAMP, Brasil, where the research described in this paper was conducted. He plans to graduate in May 2005 and begin graduate school in mathematics the following fall.
Plamen Koshlukov, Department of Mathematics, IMECC, UNICAMP, P.O. Box 6065, 13083-970 Campinas, SP, Brazil