Klaus Ambos-Spies, Serikzhan Badaev, Sergey Goncharov 0002. On a Question of Frank Stephan. In Manindra Agrawal, Ding-Zhu Du, Zhenhua Duan, Angsheng Li, editors, Theory and Applications of Models of Computation, 5th International Conference, TAMC 2008, Xi an, China, April 25-29, 2008. Proceedings. Volume 4978 of Lecture Notes in Computer Science, pages 423-432, Springer, 2008. [doi]
Abstract is missing.