Dedicated to the memory of my parents
Dvora (1913-1987) and Izhak Meir (1913-1990) Zaks
We wish to thank all those who partially supported our research on Bagemihl's conjecture
during the years we have been working on it. Most of the results were obtained while the author
was visiting A. Kotzig and G. Sabidussi at the University of Montreal, A. Bondy and other
colleagues at the C. & O. Department, University of Waterloo and R.K. Guy at the University
of Calgary; these visits were supported by the hosts' NSERC grants.
We wish to thank P. Laufer for some computations at an early stage of the research, and to
thank N. Linial for some helpful conversations concerning the Graham-Pollak Theorem.
Special thanks go to my son Ayal Zaks for the many fruitful discussions on the
computational aspects of our searches, and for his help in getting the many graphical
representations needed during the work.
We highly appreciate the effort of the referees and their many valuable comments and