Frieder Stolzenburg. An algorithm for general set unification and its complexity. Journal of Automated Reasoning, 22(1):45-63, 1999. [ http ]
Frieder Stolzenburg. Membership-constraints and complexity in logic programming with sets. In Franz Baader and Klaus U. Schulz, editors, Frontiers in Combining Systems, Applied Logic Series 3, pages 285-302. Kluwer Academic, Dordrecht, The Netherlands, 1996.
Frieder Stolzenburg. Logic programming with sets by membership-constraints. In Norbert E. Fuchs and Georg Gottlob, editors, Proceedings of 10th Logic Programming Workshop, Technical Report ifi 94.10, pages 48-51, Universität Zürich, 1994. Institut für Informatik. [ .pdf ]
Frieder Stolzenburg. An algorithm for general set unification and its complexity. In Eugenio G. Omodeo and Gianfranco Rossi, editors, Proceedings of Workshop on Logic Programming with Sets at 10th International Conference on Logic Programming, pages 17-22, Budapest, 1993.