1. James P. Jones And Douglas P. Wiens, Department of Mathematics, University of Calgary, Calgary, Alberta, Canada, T2N 1N4.
2. Daihachiro Sato, Department of Mathematics, University of Saskatchewan, Regina, Saskatchewan, Canada, S4S 0A2.
3. Hideo Wada, Department of Mathematics, Sophia University, Kioicho, Chiyoda-Ku, Tokyo, Japan.