Math

Auhor's comments: Although I have the feeling of having left unfinished almost every mathematical project undertaken, the study of endoscopy and the stabilized trace formula was, in this respect, one of the most unsatisfactory of all. It went on for a very long time without reaching any very cogent conclusions. This now seems with hindsight to have been inevitable. The efforts of a number of excellent mathematicians make it clear that the problems to be solved, many of which remain outstanding, were much more difficult than I appreciated.