@incollection{KurtzSimon2007,
  author    = {{Stuart A. Kurtz and Janos Simon}},
  title     = {{The undecidability of the generalized Collatz problem}},
  booktitle = {{Theory and Applications of Models of Computation, 4-th International Conference, TAMC 2007, Shanghai, China, May 22-25, 2007}},
  publisher = {{Springer-Verlag: New York}},
  year      = {{2007}},
  pages     = {{542--553}},
  doi       = {{10.1007/978-3-540-72504-6_49}},
  url       = {{https://link.springer.com/chapter/10.1007/978-3-540-72504-6_49}},
  note      = {{MR 2374341}},
}