Klaus Aehlig, Jolie G. de Miranda, C.-H. Luke Ong. The Monadic Second Order Theory of Trees Given by Arbitrary Level-Two Recursion Schemes Is Decidable. In Pawel Urzyczyn, editor, Typed Lambda Calculi and Applications, 7th International Conference, TLCA 2005, Nara, Japan, April 21-23, 2005, Proceedings. Volume 3461 of Lecture Notes in Computer Science, pages 39-54, Springer, 2005.
Abstract is missing.