Mathematisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany. E-mail: firstname.lastname@example.org
Recent results on initial segments of the Turing degrees are presented, and some conjectures about initial segments that have implications for the existence of nontrivial automorphisms of the Turing degrees are indicated.
(Received September 30 2002)
(Revised November 18 2002)