Jordi Levy, Manfred Schmidt-Schauß, Mateu Villaret. Monadic Second-Order Unification Is NP-Complete. In Vincent van Oostrom, editor, Rewriting Techniques and Applications, 15th International Conference, RTA 2004, Aachen, Germany, June 3-5, 2004, Proceedings. Volume 3091 of Lecture Notes in Computer Science, pages 55-69, Springer, 2004. [doi]
Abstract is missing.