Stuart A. Kurtz, Janos Simon. The Undecidability of the Generalized Collatz Problem. In Jin-yi Cai, S. Barry Cooper, Hong Zhu, editors, Theory and Applications of Models of Computation, 4th International Conference, TAMC 2007, Shanghai, China, May 22-25, 2007, Proceedings. Volume 4484 of Lecture Notes in Computer Science, pages 542-553, Springer, 2007. [doi]
Abstract is missing.