Institution: | 1. Department of Mathematics, Iowa State University, Ames, IA 50011, USA;2. Department of Mathematics, Brigham Young University, Provo, UT 84602, USA;3. American Institute of Mathematics, 360 Portage Ave, Palo Alto, CA 94306, USA;4. School of Science and Mathematics, Upper Iowa University, Fayette, IA 52142, USA |