Vikraman Arvind, T. C. Vijayaraghavan. The Orbit Problem Is in the GapL Hierarchy. In Xiaodong Hu, Jie Wang, editors, Computing and Combinatorics, 14th Annual International Conference, COCOON 2008, Dalian, China, June 27-29, 2008, Proceedings. Volume 5092 of Lecture Notes in Computer Science, pages 160-169, Springer, 2008. [doi]
Abstract is missing.