The papers in this volume are dedicated to Professor Eligiusz J. Zlot
kiewicz, on the occasion of his sixtieth birthday, by his friends, students, and colleagues.
Eligiusz J. Zlotkiewicz is an outstanding academic teacher and research worker. His ability in posing new problems and willingness to cooperate with other mathematicians and graduate students resulted in numerous joint pa
pers, as well as in six Ph.D. theses written under his direction. He was also very successful as an administrator acting as the chairman of the Math
ematics Department and the dean of the Faculty.
With best wishes of a Happy Birthday
The Editors